current research on cause of autism

What Causes Autism? Study of 100,000 Kids Reveals New Clues

From genetics to fevers, Columbia psychiatrist and epidemiologist Mady Hornig discusses the possible roots of this mysterious condition.

Autism is, for the most part, an inherited disorder: scientists estimate that up to 80 percent of a child’s risk of developing it is determined by DNA. But environmental and behavioral risk factors may also play a role, and since rates of autism in the US are at an all-time high, new and expecting parents are eager to learn more about the roots of this complex condition.

For the past two decades, a team of researchers including Michaeline Bresnahan ’99PH, Mady Hornig , W. Ian Lipkin , and Ezra Susser ’74CC, ’82VPS, ’93PH, all epidemiologists at Columbia’s Mailman School of Public Health, has been searching for nongenetic clues to explain why some kids develop autism and others do not. The researchers, in collaboration with the Norwegian Institute of Public Health and other Columbia scientists, have scrutinized the medical histories of more than one hundred thousand children, as well as those of their parents. Armed with unprecedented amounts of data, the researchers are investigating dozens of hypothesized risk factors for autism — everything from parental age to maternal infections to vitamin deficiencies. Columbia Magazine recently spoke to Hornig, who is herself the mother of an adult son with autism, about the team’s research.

What are the major risk factors for autism?

Well, a father’s age, which was one of the first risk factors identified a couple of decades ago, is certainly consequential. My colleague Ezra Susser published a major study on this subject in 2006. Using data collected in Israel, he showed that men who become fathers when they’re over the age of forty are six times more likely to have a child with autism than men who father kids before turning thirty. In 2016, I coauthored a larger study , which analyzed our Norwegian data together with information from Israel and three other countries, that confirmed the impact of paternal age while adding some new twists. We discovered that women at the beginning or end of their childbearing years — those in their teens or in their forties, roughly — are also more likely to have children with autism. And the biggest risk here is when older men have children with much younger women. There may be something about the big mismatch in age that can disrupt a child’s neurodevelopment.

Is this a reason for certain couples to avoid having children?

No, not necessarily. The thing to keep in mind is that autism is an extraordinarily complex condition that’s probably influenced by hundreds of genetic, environmental, behavioral, and dietary factors, several of which may have to co-occur and reinforce one another for the condition to arise. So even though parental age is one of the most powerful variables, it probably accounts for 5 percent or less of any child’s total risk.

Do any other factors rise to this level of importance?

One of our more recent discoveries is quite significant: we found that if a pregnant woman experiences a high fever in her second trimester, her child’s chances of developing autism increase by 40 percent. We’re not sure why this is, but molecular evidence suggests that inflammation in the mother’s body may be associated with a delay in the formation of blood vessels in the fetal brain during a critical point in the development of the central nervous system.

Does it matter what causes the fever?

We suspect that any number of viral or bacterial infections can probably have this effect, but we’d need to conduct even larger studies to know for sure. Influenza appears to be implicated: the mothers of many of the children diagnosed with autism in our cohort suffered a serious bout of influenza in the second trimester. But the type of infection seems to be less important than its severity, since it’s the fever itself — indicative of a systemic, full-body inflammatory reaction — that we found to be strongly associated with autism. That said, I wouldn’t want to be alarmist. A lot of women experience fevers while they’re pregnant and go on to have perfectly healthy kids. Again, the risk this poses for any particular child is quite small.

So what’s the takeaway for pregnant women or women who plan to get pregnant?

Get a flu shot. Get vaccinated against COVID-19. Wear a mask and practice social distancing. Keep your immune system strong by exercising and eating healthy food. And if you do get sick and have a high temperature, talk to your doctor about possibly taking an anti-inflammatory medication like ibuprofen. (Acetaminophen does not counter inflammation in the same way). Physicians have traditionally cautioned against taking ibuprofen while you’re pregnant because it carries a risk of miscarriage, especially in the first trimester, or possibly deformation of the baby’s heart if given close to the time of delivery, but administration of anti-inflammatory medications for fever during the second trimester might be discussed with one’s physician. At that stage, you really want to reduce a fever as quickly as possible.

Are any dietary factors important?

We analyzed the diets of all of the women and children who participated in our project to see if any vitamin or mineral deficiencies contribute to autism. What jumped out of the data was that women who take supplements of folic acid, or vitamin B9, early in their pregnancy are almost 40 percent less likely to have a child with autism. That wasn’t a shock because folic acid, which is found naturally in leafy vegetables, beans, and eggs, has long been known to be essential for fetal brain development. But our research revealed that folic acid supplements only protect a fetus against autism if a mother begins taking them shortly before conception and throughout the first two months of pregnancy, which is earlier than many women start on prenatal vitamins. That’s why I suggest that women who are planning a pregnancy talk to their doctors about taking prenatal supplements before they conceive.

We’ve also found preliminary evidence that heritable differences in how the body regulates levels of vitamin D in the body may be associated with autism in certain subsets of people with the condition, but we need to do additional research to confirm that.

Other researchers have claimed that altering an autistic child’s diet, such as by removing gluten, dairy, or other potential allergens, can sometimes ameliorate symptoms. Have you found any evidence that a child’s diet might contribute to the condition’s onset?

No, though it’s possible that dietary factors play such a role and that we’d just need larger studies with more statistical power to spot them. But we’ve tended to focus our investigations on pregnant women’s health in the Norway cohort because we believe that the roots of autism are likely established in the earliest stages of brain development, in the womb, and that improving our understanding of these processes holds promise for uncovering tractable pathways for prevention.

What are you looking at next?

Our findings about the role of fever in causing autism raise all sorts of questions. For example, we’d like to know if psychosocial stressors in the mother during pregnancy may pose a risk by triggering low-grade inflammation in the body that translates into neurodevelopmental risk for the child. The use of antidepressants by expectant mothers has previously been hypothesized as a risk factor for autism, but other data suggest that antidepressants themselves are unlikely to be the culprit; we’ve considered instead that underlying or untreated depression or anxiety may be the real danger.

Do you expect that we’ll see a spike in autism cases as a result of the COVID-19 pandemic?

Yes, sadly, I think that’s possible. And not just because many pregnant women have been getting COVID-19, but also because many people, pregnant women included, have been dealing with serious mental stress during the pandemic. It will be a few years before we know if autism rates rise in response, because the condition is usually diagnosed around age three or later. It is also quite likely that rates may rise more generally for a range of neurodevelopmental conditions, including ADHD.

Autism’s prevalence in the US has nearly tripled since 2000. Why?

Part of the explanation is certainly that doctors are more aware of the condition and are diagnosing it more frequently. But my colleagues and I suspect that other factors, like people having children later in life or environmental changes that are making our bodies more vulnerable to infections and immunological problems, are contributing to the uptick in cases.

You’ve spoken publicly about your own experiences raising a son with autism. Is there anything that you wish you’d known back when you were pregnant?

You know, it’s interesting, because I just discovered, through my own participation as a subject in an unrelated medical study, that I have a genetic mutation that’s known to interfere in the body’s absorption of folic acid. So this tells me that it’s possible I wasn’t getting enough folic acid when I was pregnant back in the late 1980s, even though I was taking the recommended four hundred micrograms per day. Now, did a lack of folic acid cause my son’s autism? That’s way too simplistic, because there were probably lots of genetic and environmental factors involved. Did it contribute? Maybe. I certainly wish that I’d known I was susceptible to folate deficiency when I was pregnant, because then I could have talked to my obstetrician about it and explored solutions.

What is the genetic variant you have? And are pregnant women routinely tested for it today?

The gene variant, which is carried by about 15 percent of all Americans, is located in the gene MTHFR . Pregnant women aren’t routinely tested for it, and a physician might initially balk at ordering it, unless he or she is knowledgeable of cutting-edge autism research and knows how to interpret its results. But if a woman can find a doctor who thinks the test is beneficial and she has good insurance, she might get it covered.

Are there any genomic tests that can tell an adult if he or she is likely to have a child with autism?

No, because the genetics of autism are still poorly understood. Although scientists have identified more than a hundred genes linked to the condition, we can’t say precisely what many of these genes do, nor the degree to which they increase an individual’s risk. There are some geneticists who will analyze and interpret men’s and women’s DNA in an attempt to estimate this risk. However, such analyses don’t offer definitive predictions, since we still haven’t identified all of the mutations involved in autism. Further, the influence of certain gene variants on autism may also depend on whether an individual is additionally exposed to specific environmental risks that may affect the function of that gene variant during key periods of early neural development — much as the rare inherited disorder phenylketonuria (PKU), caused by genetic mutations, can be treated by reducing or eliminating the amino acid phenylalanine from a child’s diet. A good source of information on this topic is the SPARK website of the Simons Foundation, a New York–based nonprofit that supports autism research.

Eventually, we’d like to get to the point where we’re able to recommend a whole range of preventive steps parents might take to mitigate the damaging effects of specific mutations they carry. But we still have a lot more work to do, both in terms of identifying the causes of autism and in understanding how various risk factors interact. Right now, we’re still building the scientific foundation for that kind of customized clinical care.

For more information on this research, see the following articles from Columbia's Mailman School of Public Health:

Study Identifies Biomarkers Linked to Autism Risk

Could Flu During Pregnancy Raise Risk for Autism?

Autism Risk Linked to Fever During Pregnancy

Autism Risk Linked to Herpes Infection During Pregnancy

This article appears in the Spring/Summer 2022 print edition of Columbia Magazine with the title "In search of autism's roots."

What Causes Autism? New Research Uncovers a Key Factor in Brain Development

By Texas A&M University College of Medicine July 31, 2022

The findings of this research reveal a significant component in the underlying causes of neural tube birth defects, intellectual disabilities, and autism risk.

Researchers from Texas A&M College of Medicine have provided answers to important questions concerning how the neocortex develops, providing new information about the root causes of intellectual disabilities.

A significant advancement in our understanding of how the brain develops has been accomplished by researchers at Texas A&M University College of Medicine . This new research advances our understanding of how the region of the brain that distinguishes humans from other animals develops and sheds light on what causes intellectual disabilities, such as autism spectrum disorders.

For many years, scientists have recognized a significant relationship between mammalian intelligence and a thin layer of cells in the neocortex, the region of the brain that governs higher-order processes like cognition, perception, and language. The neocortex’s surface area reflects how highly developed an organism’s mental ability is. For instance, the human neocortex is only around three times thicker than the mouse equivalent. However, the human neocortex has a 1,000-fold larger surface area than that of mice. Autism spectrum disorders and intellectual impairments are among the developmental deficiencies caused by malformations in this region of the brain.

What is unknown is how evolutionary expansion of this section of the brain happens selectively in favor of growing the neocortex’s surface area at the cost of increasing its thickness. An important aspect of this process is how the initial populations of neural stem cells, which serve as the brain’s building blocks, distribute themselves.

“There are many, what we’ll call, individual processing units that are horizontally arranged in the neocortex. The more surface area you have, the more of these processing units you can accommodate,” said Vytas A. Bankaitis, Distinguished Professor at the College of Medicine, E.L. Wehner-Welch Foundation Chair in Chemistry, and co-author of this study, which was published in Cell Reports . “The question is, why is the neocortical surface area so much greater relative to its thickness as one climbs up the mammalian evolutionary tree? Why do neural stem cells spread themselves in a lateral direction as they proliferate and not pile on top of each other?”

This question is key because when the cells do not spread out, but instead pile up, it creates a thicker neocortex with a smaller surface area — a characteristic that has been observed in cases of intellectual disability and even autism.

“One of the most studied genetic causes of intellectual disability is a mutation in a gene that was originally called LIS1,” said Zhigang Xie, assistant professor at the College of Medicine and co-author of the study. “This genetic mutation will cause a smooth brain, which is associated with intellectual disability. And one typical observation is that the neocortex of the patient is thicker than normal. There are also very recent studies that identify common differences in the brain of autism that include abnormally thickened regions of the neocortex in those individuals.”

Scientists have known for some time that as neural stem cells divide, their nuclei move up and down within their anatomical space as a function of the cell cycle, a process called interkinetic nuclear migration. They do so by employing a cytoskeletal network that acts like train tracks with engines that move the nuclei up or down in a closely regulated manner. Although several ideas have been proposed, it remains an enigma why the nuclei move in this way, how this network of train tracks is controlled, and what role interkinetic nuclear migration plays in development of the neocortex.

In their study, Xie and Bankaitis provide answers to these questions.

As for why, Bankaitis explains that when there are so many cells so close together in the embryonic stage of neocortical development, the movement of their nuclei up and down causes opposing upward and downward forces that spreads the dividing neural stem cells out.

“Think about a tube of toothpaste,” Bankaitis said. “If you were to take that toothpaste tube, put it between your hands, push up from the bottom and push down from the top, what would happen? It would flatten and spread out. That’s essentially how this works. You have an upward force and a downward force caused by the movement of the nuclei that spreads these cells out.”

Xie and Bankaitis also demonstrate how the cells do this by linking together several distinct pathways that cooperate to “tell” the newborn neural stem cells where to go.

“I think for the first time, this really puts together molecules and signaling pathways that indicate how this process is controlled and why it would be linked or associated with neurodevelopmental deficiencies,” Bankaitis said. “We have taken a biochemical pathway, linked it to a cell biological pathway, and linked it to a signaling pathway that talks to the nucleus to promote the nuclear behavior that generates a force that develops a complicated brain. It’s now a complete circuit.”

The results of this study uncover an important factor in the underlying causes of autism risk, intellectual disabilities and neural tube birth defects. The new knowledge on the basic principles regulating the shape of the neocortex will also help the design of in vitro brain culture systems that more accurately reflect the developmental processes of interest and improve the prospects for neurological drug development.

“While there might prove to be many reasons why a neocortex thickens instead of spreads, our work provides a new perspective on why patients with autism and intellectual disabilities often display a thicker cortex,” Xie said. “The fact that the LIS1 gene product is a core regulator of nuclear migration, including the interkinetic nuclear migration that we study in this work, supports the conclusions we reach in this paper.”

Reference: “Phosphatidylinositol transfer protein/planar cell polarity axis regulates neocortical morphogenesis by supporting interkinetic nuclear migration” by Zhigang Xie and Vytas A. Bankaitis, 31 May 2022, Cell Reports. DOI: 10.1016/j.celrep.2022.110869

The study was funded by the NIH/ National Institutes of Health and the Robert A Welch Foundation.

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New Stanford Research Shows Differences Between Brains of Girls and Boys With Autism

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17 comments on "what causes autism new research uncovers a key factor in brain development".

I just wonder how does the thicker neucortex in Humans and other mammals collate to the Âûtistic and Co-morbidity genes that we Neurodiverse persons have and explain brighter hundreds of percent more almost hyperactivity in Right hemisphere, Tempora, Frontal lobes and Amygdala, compared to greyzones and work around in reduced activity left hemisphere and the thousands of Autism Genome Project Autistic, Co-morbidity and mutations in a few million Autistic and Co-morbidity confirmed participants recorded as 1 in 5.8 and 1 in 5.9 in Denmark and Sweden by cottaging of many multiple traits, Co-morbidities and coping mechanisms.

Autism isn’t a disability. If autism is a disability, thing so is womanhood.

Ok, Peter. Once you figure out what causes the disability in those identified autistic then you can make that declaration. Until then, and within the household I exist in, there are strengths in the identity, but in the same vein, there are also several disabling aspects as well. Hence it IS a disability. When people make bold statements like this, they are slowly creating a reality where supports could be taken away to those most profoundly affected since they are trying to sell the idea that “it’s not a disability.”

Tylenol is currently being called out for knowing that their drug causes autism and not releasing those findings.

While plenty of autistic people are disabled I’m not sure we can really say autism is a disability. It’s certainly not an intellectual disability. There is a high co-morbidity with other disorders, some of which are more of a disability than others but there are plenty of autistic people who are no less capable than any autistic person. Sometimes the same traits that appear to be a disability in some situations can be an advantage in others. My son is very sensitive to sound, he gets overwhelmed easily and I can see how and why that’s perceived as a disability. However, I have the same sensitivity and, while it was stressful and difficult in childhood, as an adult I have a great ear for subtle differences in sound. That’s an advantage in music and vocal impressions, it also allows me to identify what my children are doing without looking at them. I know the sound of pretty much every toy and surface. So perhaps suitability to environment varies and it’s not so clear cut as disability/not a disability. This can apply to traits that no one calls disabilities too. Some people love cold weather, I can’t function in cold weather at all but I’m not uncomfortable at 90 degrees. My lack of tolerance to the cold isn’t a disability but it does make me unsuited to a cold environment. In the same way we could say that autistic children who have meltdowns in chaotic environments are simply unsuited to noisier, more urban environments. Without a significant improvement of our understanding of what exactly autism is, how it works, where to draw the line between autism and its comorbidities, I suppose it’s open to debate. As a side note, when someone says “autism isn’t a disability”, it might be worth considering that they could be autistic and not see themselves as disabled, or the parent of an autistic child who doesn’t find the experience disabling. I am autistic and don’t consider myself disabled. I have two children who have been diagnosed with autism, one of whom is non-verbal. Those diagnoses don’t guarantee disability payments in and of themselves in my corner of the world anyway.

“plenty of autistic people who are no less capable than any allistic person.” Autocorrect doesn’t know the word allistic aparently.

How can we trust any research coming out of Texas a&m when they allow such egregious conflicts of interest in their programs?

Doing beef research and taking donations from organizations connected to the beef industry, and then not reporting it in their research?

They better get their house in order or might as well shut down the school.

Reading this make more questions, why does it affect more boys? and why is it that we are seeing so many cases? This finding is great but we need to find out the cause enviro, consumption foods products? We have 2-3% of Canadians are affected by this diagnosis.

My IQ is 135. I have hyperlexia with full reading comprehension. I have read a lot of credible medical literature which states that Autism/ASD is a neurodevelopmental disorder, not an intellectual disorder.

Autism isn’t an intellectual disability. The first paragraph says “… and sheds light on what causes intellectual disabilities, such as autism spectrum disorders”. The rest of the article uses “intellectual disabilities and autism” which accurately reflects the research findings. This needs to be edited as makes the authors appear ignorant to anyone who knows anything about autism.

Try tô find reasons of autism in vaccination.

As someone who can or at least say I am not autistic not that I have been told by a Dr so please read this as a possibly dumb by honest question anyway but my best friend has a son that is autistic or has a form of it possibly we are close and watched him as he grew up and I noticed some of the things about him seems like habits ,disliking change and not understanding sarcasm so I guess my question is was he born autistic because his sister and his brother are not was it in his genes or d.n.a.? Or can children develop autism threw outside factors?

While there may indeed be some truth to this, as I think there is, there is still much about it I am questioning. Yes, this research supposedly provides some possible answers, but there are also quite a few unanswered questions and vital missing pieces of this complicated “intellectual disability” puzzle. Which for the record, is incorrectly titled since Autism is in fact NOT technically considered an intellectual disability, but instead a neurological one. And not even a disability. It’s labeled a disorder. And many people would argue with that. But for time, sanity, and technicality sake, it’s a disorder. Regardless, I wish I had more hope in this but if the people doing this work are comparing and calling Autism the same as intellectual disabilities…well, let’s just say i have my doubts.

This was a great article. Hats off to the team finding these correlations and observations. These are the findings that lead us in directions that hold answers.

It’s so sad to read these comments. Questioning these scientific finding because of the funding channels uses as an o stitution..situation… arbitrarily saying that autism shouldn’t be considered a disability because of personal observations of qualitative factors is mind blowing. It’s as though there is an entire wave of people who are not being taught how anything on the world actually works. Or why. Clearly discernment has left the building.

If one wants to protect the status quo of autism, I just can’t begin to fathom why but thats not important, which is something alot of you could learn, but back to the issue, if you convince the world over that autism should not be looked at as a disabilty then you better take a long hard look at yourself in the mirror and ask yourself a few questions: 1. Do you have any business voicing opinions like that on platforms that are far reaching? Let me translate for the younger crowd… do you have any scientific/educational/vocational credentials that support your words as anything more than an opinion or thought? If so, pipe down. 2. If your message hits and the world over decides it is not a disabilityany more, research will cease. Do I understand the power of change? Have I performed efficacy studies that support making this change or am I only doing this for the fluffy feelings Inside me?

Honestly, I read about all these school shootings and I’m always surprised when I find out the shooter WASNT a teacher.

Good luck to those of you who are unknowingly barking for research, similar to that performed in this article, to stop. You’re the real disability in the world. You’ve convinced us all.

My son was born in 2009. Extra genetic material on line 16, tourette’s syndrome followed at age 3, ADHD, OCD, and lastly behavioral problems. No doctor out of the 20+ doctors we seen knew how to treat or help him. I am sad daily as I had to place him in his father’s care. I have 6 children under 12yo. He would look for any opportunity to get too one of his sister’s and beat them until he seen blood. He would laugh and think it was so cool. I wish I knew what went so wrong.

I am a 73 year old recently retired physician, very successful in my 45 year career. As my brain has gradually reaclimated to “normal” life after 45 years on constant “high alert”, I have noticed a reemergence of intellectual, cognitive and social patterns of function which are very suggestive of ASD, and which were evidently unlearned during my decades of acquired “normal” behavior. Throughout my life I have dealt with often awkward and cringy social abilities. Many professional, personal and romantic relationships suffered from my unique ability to sabotage them. Since I come from a family in which nearly all males of one lineage (my paternal grandfather’s) are clearly on the spectrum, I’ve realized, for the first time that I am as well. A few of these males are/were severely disabled, but much more frequently they are like me — reasonably social but with an awkwardness which is counterbalanced by savant abilities which allow us to reach high levels of mastery in fields like medicine and teaching. All of us seem to have high levels of social justice awareness, which only seems to add to our perceived level of occupational success. It is becoming clear to me, looking back on my family’s four generations of approximately 90% incidence of ASD among the men, that this persistence of a high incidence of ASD would not occur unless the autistic spectrum disorders are a normal variant of human intellectual and social development. In other words, ASD must be normal-ish, must have served some sort of social purpose during the Ice Age, for them to persist this long. It’s not hard to imagine there being an advantage for a tribe to include a member who thinks somewhat like game animals, a la Temple Grandin; or a member like myself who appears to have an ability to see connections between seemingly unrelated abstractions; or a member who sees off-kilter dream-like narrative explanations for disturbing events in the environment — proto- myths and stories. It may be that our abilities are not needed since the evolution of culture, or perhaps these functions have been assumed and performed by new agents within the culture. Whatever, it’s clear to me, at least, that the ASD are not disorders, developmental abberrations or illnesses. Our oddball abilities should be cultivated, while we are taught how to work around our cringiness.

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Autism Prevalence Rises Again, Study Finds

The pandemic may have disrupted the detection of autism spectrum disorder in young children, researchers also reported.

A boy wearing a gray hoodie and black sweatpants holds a colorful bubble gun in his left hand while gleefully catching bubbles with his right at an autism awareness event in a parking lot on a sunny day. Several adults sit at tables in the background.

By Emily Anthes

The prevalence of autism spectrum disorder in American children rose between 2018 and 2020, continuing a long-running trend , according to a study released by the Centers for Disease Control and Prevention on Thursday. In 2020, an estimated one in 36 8-year-olds had autism, up from one in 44 in 2018. The prevalence was roughly 4 percent in boys and 1 percent in girls.

The rise does not necessarily mean that autism has become more common among children, and it could stem from other factors, such as increased awareness and screening.

“I have a feeling that this is just more discovery,” said Catherine Lord, a professor of psychiatry at the University of California, Los Angeles medical school, who was not involved in the research. “The question is what’s happening next to these kids, and are they getting services?”

The rise was especially sharp among Black, Hispanic, and Asian or Pacific Islander children. For the first time, autism was significantly more prevalent among 8-year-olds in these groups than in white children, who have traditionally been more likely to receive autism diagnoses.

“These patterns might reflect improved screening, awareness and access to services among historically underserved groups,” the researchers wrote.

But why the prevalence in these children has surpassed that in white children is an open question that requires more investigation, Dr. Lord said.

An accompanying study, also published on Thursday, suggests that the pandemic may have disrupted or delayed the detection of autism in younger children.

For this analysis, the researchers compared the number of autism evaluations and identifications for children who were 4 years old in 2020 to the equivalent numbers from four years earlier. In the six months before the pandemic began, autism evaluations and identifications were higher among the 4-year-olds than they had been in young children four years prior.

That is good news, Dr. Lord said. “It means we’re finding kids younger.”

But after March 2020, when the World Health Organization declared Covid-19 a pandemic, autism evaluations and detections plummeted, remaining below prepandemic levels through the end of 2020, the researchers reported.

Parents may have been less likely to bring their children in for autism evaluations during the pandemic, Dr. Lord said. The closure of schools and the shift to remote learning may have also made it harder for educators to identify children who might have benefited from evaluations or services.

“Disruptions due to the pandemic in the timely evaluation of children, and delays in connecting children to the services and support they need, could have long-lasting effects,” Dr. Karen Remley, director of the C.D.C.’s National Center on Birth Defects and Developmental Disabilities, said in a statement.

Both studies are based on data from the Autism and Developmental Disabilities Monitoring Network , which has used health and education records to track autism in communities across the United States since 2000.

The network has documented an increase in autism prevalence since 2000 , when approximately one in 150 8-year-olds were estimated to have autism.

The 2020 data come from sites in 11 states and are not necessarily representative of the nation as a whole. Data from other locations could help provide a more comprehensive picture, Dr. Lord said.

Emily Anthes is a reporter for The Times, where she focuses on science and health and covers topics like the coronavirus pandemic, vaccinations, virus testing and Covid in children. More about Emily Anthes

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Science News

Aimee grant investigates the needs of autistic people.

Her research focuses on reproductive health care

Aimee Grant is sitting on a wheelchair against a white wall. She has a short, purple hair and wearing glasses, a necklace and a black short-sleeve dress with white flower pattern. She also has tattoos on her right arm.

Public health researcher Aimee Grant considers autism a cognitive difference, rather than a deficit.

Matthew Arthur

Reimagining autism research

Grant’s work aims not only to serve study participants, but also to amplify their voices. By aggregating personal accounts, her research gives participants’ testimonies weight they often lack on their own, Henry says.

In one breastfeeding study, published last November in Maternal & Child Nutrition , Grant’s team surveyed 152 autistic birthing parents in the United Kingdom . The team found that nearly 70 percent of participants enjoyed breastfeeding overall. But 45 percent reported dealing with pain roughly half the time or more. One parent likened the feeling of the let-down reflex that gets breastmilk flowing to “an old-fashioned telephone ringing in my breasts.”

Still, most remained committed to breastfeeding, which the World Health Organization recommends women do exclusively for at least six months. The parents came up with creative solutions to ease their discomfort, including wearing clothing that exposed less of the most sensitive skin, wearing nipple shields and distracting themselves with videos or games on their phones.

Parents who received support from health care professionals, such as midwives or lactation consultants, tended to have a much easier time with breastfeeding. But nearly half of study participants had a negative interaction with at least one clinician, either struggling to access services, receiving incomplete or conflicting health information, or even feeling that their struggles were flat-out dismissed.

In the United Kingdom, just 1 percent of all mothers meet the WHO’s six-month recommendation, according to the latest available data from 2010. Grant and colleagues attribute this low rate to structural impediments, such as inadequate support for breastfeeding parents and aggressive campaigning by the formula industry, not to a lack of trying on the part of parents.

Grant says she has always wanted to “change perceptions about groups,” especially those criticized in the media, in regards to the broader ethos of her work, “to help the wider public recognize just how hard that group is working.”

To shed light on things that might not be known by policy makers, Grant has communicated her findings to the public in news articles and at conferences. The YouTube channel she helped launch now features more than a hundred clips of autistic parents and maternity experts sharing their expertise.

In 2022 Grant won a $3 million grant for an expansive study characterizing the broad reproductive health care needs of autistic people with wombs, from menstruation to menopause. The project, funded by Wellcome, will recruit 100 participants, interviewing them every six months for a total of five years.

“There’s a lot more questions than answers at the moment,” Grant says. Some of her team’s questions include: How can individuals manage the sensation of a period cramp or of ultrasound gel? What contraceptives do participants use, and what are their experiences? Are there differences in how autistic people sense and communicate bodily pain to health care professionals compared with what the research says of nonautistic people?

A project of such size and duration will identify areas where autistic people’s health care needs are not being met, Grant predicts. It may uncover positives of the autistic experience, as well as new avenues for research. Her team plans to keep the interviews loosely structured to “give people the space to talk about the things that are important to them.”

The team — made up entirely of autistic researchers — aims to capture the diversity within the community by partnering with autism organizations that serve individuals of various ethnic backgrounds and learning abilities, by paying participants for their time and for sign language interpreters if needed, and by allowing participants to choose to respond to questions through a video call, on the phone or via email. The researchers will also use their own neurodivergent perspectives to anticipate hurdles for participants: for example, putting text in fonts and colors that are easier to read or eliminating exclusionary phrases such as “autistic women,” which leaves out transgender and nonbinary people with wombs.

Grant is “really one of those practice-what-you-preach people,” says Rebecca Ellis of Swansea, one of four research assistants working on the project. “She is continually making sure that she can be as inclusive as possible and amplify the voices that get heard the least.”

Keeping an open mind

Grant doesn’t claim to have the single answer on what research on autism should look like; she’s committed to having an open mind. “I’m sure in 10 years we’ll have even more of a social model of autism,” she says, referring to a well-established view of autism as a disability constructed in large part by society, “and where we are now will seem outdated.” For now, she’s helping to get different perspectives in the room, collecting evidence for the theory that one’s environment can be more disabling than one’s predisposition.

Grant’s path to science may be part of what makes her work so unconventional.

Growing up, she did not expect to become a researcher. Her father was a firefighter, and her mother a housewife. In school, she just kept pursuing “the next thing that was interesting.” She attributes where she is today in large part to chance.

She pursued a Ph.D. in social policy at Cardiff University, where she studied competing political narratives around disability-benefit users, debunking a prominent myth that claimants were exploiting the welfare system. After completing that work, she needed to find a job near her home in order to reserve a spot on a waiting list for much-needed surgery. She worked in Cardiff as a research assistant, studying how well the National Health Service’s smoking cessation programs work, and then was asked to shift her focus to maternity. After her own autism diagnosis, she began to focus on autistic parents.

Along the way, she tended to be drawn to and stick with jobs with a social justice ethos. “My work has a purpose: to make lives better for marginalized groups,” she says. “It’s almost painful for me to do research that isn’t in those areas.”

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Patient Care & Health Information
Diseases & Conditions
Autism spectrum disorder

Autism spectrum disorder is a condition related to brain development that impacts how a person perceives and socializes with others, causing problems in social interaction and communication. The disorder also includes limited and repetitive patterns of behavior. The term "spectrum" in autism spectrum disorder refers to the wide range of symptoms and severity.

Autism spectrum disorder includes conditions that were previously considered separate — autism, Asperger's syndrome, childhood disintegrative disorder and an unspecified form of pervasive developmental disorder. Some people still use the term "Asperger's syndrome," which is generally thought to be at the mild end of autism spectrum disorder.

Autism spectrum disorder begins in early childhood and eventually causes problems functioning in society — socially, in school and at work, for example. Often children show symptoms of autism within the first year. A small number of children appear to develop normally in the first year, and then go through a period of regression between 18 and 24 months of age when they develop autism symptoms.

While there is no cure for autism spectrum disorder, intensive, early treatment can make a big difference in the lives of many children.

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Children’s Book: My Life Beyond Autism

Some children show signs of autism spectrum disorder in early infancy, such as reduced eye contact, lack of response to their name or indifference to caregivers. Other children may develop normally for the first few months or years of life, but then suddenly become withdrawn or aggressive or lose language skills they've already acquired. Signs usually are seen by age 2 years.

Each child with autism spectrum disorder is likely to have a unique pattern of behavior and level of severity — from low functioning to high functioning.

Some children with autism spectrum disorder have difficulty learning, and some have signs of lower than normal intelligence. Other children with the disorder have normal to high intelligence — they learn quickly, yet have trouble communicating and applying what they know in everyday life and adjusting to social situations.

Because of the unique mixture of symptoms in each child, severity can sometimes be difficult to determine. It's generally based on the level of impairments and how they impact the ability to function.

Below are some common signs shown by people who have autism spectrum disorder.

Social communication and interaction

A child or adult with autism spectrum disorder may have problems with social interaction and communication skills, including any of these signs:

Fails to respond to his or her name or appears not to hear you at times
Resists cuddling and holding, and seems to prefer playing alone, retreating into his or her own world
Has poor eye contact and lacks facial expression
Doesn't speak or has delayed speech, or loses previous ability to say words or sentences
Can't start a conversation or keep one going, or only starts one to make requests or label items
Speaks with an abnormal tone or rhythm and may use a singsong voice or robot-like speech
Repeats words or phrases verbatim, but doesn't understand how to use them
Doesn't appear to understand simple questions or directions
Doesn't express emotions or feelings and appears unaware of others' feelings
Doesn't point at or bring objects to share interest
Inappropriately approaches a social interaction by being passive, aggressive or disruptive
Has difficulty recognizing nonverbal cues, such as interpreting other people's facial expressions, body postures or tone of voice

Patterns of behavior

A child or adult with autism spectrum disorder may have limited, repetitive patterns of behavior, interests or activities, including any of these signs:

Performs repetitive movements, such as rocking, spinning or hand flapping
Performs activities that could cause self-harm, such as biting or head-banging
Develops specific routines or rituals and becomes disturbed at the slightest change
Has problems with coordination or has odd movement patterns, such as clumsiness or walking on toes, and has odd, stiff or exaggerated body language
Is fascinated by details of an object, such as the spinning wheels of a toy car, but doesn't understand the overall purpose or function of the object
Is unusually sensitive to light, sound or touch, yet may be indifferent to pain or temperature
Doesn't engage in imitative or make-believe play
Fixates on an object or activity with abnormal intensity or focus
Has specific food preferences, such as eating only a few foods, or refusing foods with a certain texture

As they mature, some children with autism spectrum disorder become more engaged with others and show fewer disturbances in behavior. Some, usually those with the least severe problems, eventually may lead normal or near-normal lives. Others, however, continue to have difficulty with language or social skills, and the teen years can bring worse behavioral and emotional problems.

When to see a doctor

Babies develop at their own pace, and many don't follow exact timelines found in some parenting books. But children with autism spectrum disorder usually show some signs of delayed development before age 2 years.

If you're concerned about your child's development or you suspect that your child may have autism spectrum disorder, discuss your concerns with your doctor. The symptoms associated with the disorder can also be linked with other developmental disorders.

Signs of autism spectrum disorder often appear early in development when there are obvious delays in language skills and social interactions. Your doctor may recommend developmental tests to identify if your child has delays in cognitive, language and social skills, if your child:

Doesn't respond with a smile or happy expression by 6 months
Doesn't mimic sounds or facial expressions by 9 months
Doesn't babble or coo by 12 months
Doesn't gesture — such as point or wave — by 14 months
Doesn't say single words by 16 months
Doesn't play "make-believe" or pretend by 18 months
Doesn't say two-word phrases by 24 months
Loses language skills or social skills at any age

There is a problem with information submitted for this request. Review/update the information highlighted below and resubmit the form.

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Autism spectrum disorder has no single known cause. Given the complexity of the disorder, and the fact that symptoms and severity vary, there are probably many causes. Both genetics and environment may play a role.

Genetics. Several different genes appear to be involved in autism spectrum disorder. For some children, autism spectrum disorder can be associated with a genetic disorder, such as Rett syndrome or fragile X syndrome. For other children, genetic changes (mutations) may increase the risk of autism spectrum disorder. Still other genes may affect brain development or the way that brain cells communicate, or they may determine the severity of symptoms. Some genetic mutations seem to be inherited, while others occur spontaneously.
Environmental factors. Researchers are currently exploring whether factors such as viral infections, medications or complications during pregnancy, or air pollutants play a role in triggering autism spectrum disorder.

No link between vaccines and autism spectrum disorder

One of the greatest controversies in autism spectrum disorder centers on whether a link exists between the disorder and childhood vaccines. Despite extensive research, no reliable study has shown a link between autism spectrum disorder and any vaccines. In fact, the original study that ignited the debate years ago has been retracted due to poor design and questionable research methods.

Avoiding childhood vaccinations can place your child and others in danger of catching and spreading serious diseases, including whooping cough (pertussis), measles or mumps.

Risk factors

The number of children diagnosed with autism spectrum disorder is rising. It's not clear whether this is due to better detection and reporting or a real increase in the number of cases, or both.

Autism spectrum disorder affects children of all races and nationalities, but certain factors increase a child's risk. These may include:

Your child's sex. Boys are about four times more likely to develop autism spectrum disorder than girls are.
Family history. Families who have one child with autism spectrum disorder have an increased risk of having another child with the disorder. It's also not uncommon for parents or relatives of a child with autism spectrum disorder to have minor problems with social or communication skills themselves or to engage in certain behaviors typical of the disorder.
Other disorders. Children with certain medical conditions have a higher than normal risk of autism spectrum disorder or autism-like symptoms. Examples include fragile X syndrome, an inherited disorder that causes intellectual problems; tuberous sclerosis, a condition in which benign tumors develop in the brain; and Rett syndrome, a genetic condition occurring almost exclusively in girls, which causes slowing of head growth, intellectual disability and loss of purposeful hand use.
Extremely preterm babies. Babies born before 26 weeks of gestation may have a greater risk of autism spectrum disorder.
Parents' ages. There may be a connection between children born to older parents and autism spectrum disorder, but more research is necessary to establish this link.

Complications

Problems with social interactions, communication and behavior can lead to:

Problems in school and with successful learning
Employment problems
Inability to live independently
Social isolation
Stress within the family
Victimization and being bullied

More Information

Autism spectrum disorder and digestive symptoms

There's no way to prevent autism spectrum disorder, but there are treatment options. Early diagnosis and intervention is most helpful and can improve behavior, skills and language development. However, intervention is helpful at any age. Though children usually don't outgrow autism spectrum disorder symptoms, they may learn to function well.

Autism spectrum disorder (ASD). Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/autism/facts.html. Accessed April 4, 2017.
Uno Y, et al. Early exposure to the combined measles-mumps-rubella vaccine and thimerosal-containing vaccines and risk of autism spectrum disorder. Vaccine. 2015;33:2511.
Taylor LE, et al. Vaccines are not associated with autism: An evidence-based meta-analysis of case-control and cohort studies. Vaccine. 2014;32:3623.
Weissman L, et al. Autism spectrum disorder in children and adolescents: Overview of management. https://www.uptodate.com/home. Accessed April 4, 2017.
Autism spectrum disorder. In: Diagnostic and Statistical Manual of Mental Disorders DSM-5. 5th ed. Arlington, Va.: American Psychiatric Association; 2013. http://dsm.psychiatryonline.org. Accessed April 4, 2017.
Weissman L, et al. Autism spectrum disorder in children and adolescents: Complementary and alternative therapies. https://www.uptodate.com/home. Accessed April 4, 2017.
Augustyn M. Autism spectrum disorder: Terminology, epidemiology, and pathogenesis. https://www.uptodate.com/home. Accessed April 4, 2017.
Bridgemohan C. Autism spectrum disorder: Surveillance and screening in primary care. https://www.uptodate.com/home. Accessed April 4, 2017.
Levy SE, et al. Complementary and alternative medicine treatments for children with autism spectrum disorder. Child and Adolescent Psychiatric Clinics of North America. 2015;24:117.
Brondino N, et al. Complementary and alternative therapies for autism spectrum disorder. Evidence-Based Complementary and Alternative Medicine. http://dx.doi.org/10.1155/2015/258589. Accessed April 4, 2017.
Volkmar F, et al. Practice parameter for the assessment and treatment of children and adolescents with autism spectrum disorder. Journal of the American Academy of Child and Adolescent Psychiatry. 2014;53:237.
Autism spectrum disorder (ASD). Eunice Kennedy Shriver National Institute of Child Health and Human Development. https://www.nichd.nih.gov/health/topics/autism/Pages/default.aspx. Accessed April 4, 2017.
American Academy of Pediatrics policy statement: Sensory integration therapies for children with developmental and behavioral disorders. Pediatrics. 2012;129:1186.
James S, et al. Chelation for autism spectrum disorder (ASD). Cochrane Database of Systematic Reviews. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010766.pub2/abstract;jsessionid=9467860F2028507DFC5B69615F622F78.f04t02. Accessed April 4, 2017.
Van Schalkwyk GI, et al. Autism spectrum disorders: Challenges and opportunities for transition to adulthood. Child and Adolescent Psychiatric Clinics of North America. 2017;26:329.
Autism. Natural Medicines. https://naturalmedicines.therapeuticresearch.com. Accessed April 4, 2017.
Autism: Beware of potentially dangerous therapies and products. U.S. Food and Drug Administration. https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm394757.htm?source=govdelivery&utm_medium=email&utm_source=govdelivery. Accessed May 19, 2017.
Drutz JE. Autism spectrum disorder and chronic disease: No evidence for vaccines or thimerosal as a contributing factor. https://www.uptodate.com/home. Accessed May 19, 2017.
Weissman L, et al. Autism spectrum disorder in children and adolescents: Behavioral and educational interventions. https://www.uptodate.com/home. Accessed May 19, 2017.
Huebner AR (expert opinion). Mayo Clinic, Rochester, Minn. June 7, 2017.

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Kirsty Orton and her son, Fynn, sitting on her knee on a sofa

A new understanding: how research into autism is evolving

With an emphasis on working with autistic people to design interventions, pathways are opening up through social communication therapy and drug trials

K irsty Orton didn’t mind whether her baby was autistic or not – she just wanted her 12-month-old to enjoy being with his mummy: to notice her when she came into the room. To meet her eye when she talked to him and to be able to communicate.

“All I wanted to do was be able to connect and bond with Fynn,” she said. “But when your baby looks everywhere else in the room except at you and stays in their own zone, like you’re completely unimportant to them, it’s upsetting in a way that I struggle to put into words.”

Orton reiterates that it wasn’t about not accepting the autism that runs in her family. “I was fine with that,”’ she said. “But Fynn’s lack of communication wasn’t safe for a child and would be even less safe as he grew up: you need to be able to communicate if there’s something you don’t like.”

Orton, who lives in Kent, turned to the internet and discovered the first experimental trial of a targeted social communication therapy programme for babies as young as 10 months old with an increased chance of developing autism.

The pilot therapy – still in its infancy – aims to support and maximise the babies’ communication and brain function by focusing on the one-to-one social interaction they receive in their first year with parents or carers. It hopes to change later behaviour too, as the child ages.

Led by Prof Jonathan Green and his colleagues, and based on work funded by the Medical Research Council, the charity Autistica and the national autism team at NHS England, the project claims to improve the developmental trajectory of babies. Autistic children will still have developmental differences but will be more easily social and able to engage.

“This is going to change our concept of what autism is,” said Green, a professor of child and adolescent psychiatry at the University of Manchester. “It will redirect our attention away from an idea of intrinsic social impairments and get us into a deeper level of what autism is really about.”

Autism research has transformed in the last two to three decades. Gone are the offensive and misguided attempts to “cure” the condition – the depersonalised, medicalised approaches that treated autistic people as objects in need of treatment.

Gone too is the discredited and controversial approach of teaching autistic children to hide their autistic identities using behavioural techniques.

Green said: “Treatment, as it was traditionally given, focused on removing autistic behaviour and came to be felt by many autistic people to be an assault on their identity. A focus on genetic ‘cures’ led to concerns that the aim was to remove autism from the world.”

But despite the evolution of research into autism, there is still so much we don’t understand about the condition that continuing work is crucial.

We don’t understand, for example, how its many genetic and environmental influences give rise to so many different presentations. And importantly, despite the condition’s impact and prevalence, and the fact autistic people do not always respond to conventional treatments for mental health difficulties or may experience unacceptable side effects, there are still no specifically tailored medications.

Research is now striving to address those issues, and many others. But it is doing so by using a participatory approach: engaging with the autistic community and co-designing interventions focused on developing an empathic understanding of the autistic experience. Researchers then take that understanding and use it to devise environmental adjustments to help autistic people flourish.

Green’s therapy aims to modify aspects of the infant’s environment by helping parents understand their child’s communication style and adapt their own responses to it. Families who have taken part in his project talk of vastly improved outcomes for their children, deeper connections and transformed relationships.

He said: “What we’ve shown is that children whose parents have gone through our process are still autistic but are better adapted and happier individuals.

“We have proved that our early interventions, both iBasis and the version for older children, called Pact, change a child’s autistic profile in a way which suggests a whole range of autistic expressions – not making eye contact, repetitive behaviours, not communicating and so on – can often be seen as secondary products of environmental experience rather than necessary parts of the autism itself.

“It’s such a success that I would dearly like to see it proposed as a new model for early-years autism services nationwide.”

Green’s is far from the only project working hard to make a fundamental difference to autistic people’s life experience. Declan Murphy is leading the National Autism Project, the largest autism research network in the world. Funded by the EU and conducted across 14 countries with 48 partners, he hopes to have results as early as May 2025.

Murphy, from King’s College London, is exploring drugs to modify the brain signals in autistic individuals to, he said, modify the differences between them and neurotypicals. “This is not a cure – we don’t think like that any more,” he said.

What the drugs do is modify sensory processing, for example visual, thereby improving symptoms for issues that can cause many autistic people distress, including sensory sensitivity and irritability.

The exciting thing about Murphy’s research, part funded by the National Institute for Health Research Maudsley Biomedical Research Centre, is that he is using drugs that already have regulatory approval and are commonly used for other conditions, so if his study results are a success, the treatments could be introduced immediately.

Murphy said: “At the moment it looks like 30% to 40% of individuals have a significant brain response to this drug. If that translates into a clinical trial outcome then this could have massive implications for the lives of one-third of all autistic people, reducing pressure on services by the same proportion.”

Dr Grainne McAlonan, a clinical professor of translational neuroscience at the department of forensic and neurodevelopmental sciences and Institute of Psychiatry, Psychology and Neuroscience at King’s College London, has just started investigating a psychedelic compound – psilocybin – found in magic mushrooms .

She is looking at the serotonin pathway, which plays a key role in a range of essential functions such as sensory processing, cognition, mood and sleep. One of the most consistent findings in autism research are differences in the serotonin pathway: more than 25% of autistic people have high blood serotonin levels.

If McAlonan identifies individual differences in the brain serotonin system targeted by psilocybin, the next step will be to ask whether they can establish if there is a biological response to the drug that might be clinically useful. “Ultimately, this research may allow us to provide more personalised choices for those autistic people who want the option of a medication for their difficulties,” she said.

This was an exciting time for autism research, said Matthew Swindells, an evidence, research and evaluation manager at the National Autistic Society.

He points to other research that addresses real-life issues, including the Bridging Project led by the University of Plymouth, which uses virtual reality to reduce the autism employment gap; autism in affinity spaces , led by Queen Mary University London, which explores how young autistic people use social media platforms to engage in their interests; and Audit 50 , led by University College London, which focuses on the experiences of older autistic people, an often overlooked population.

Swindells said: “Perhaps, most importantly, researchers have moved away from stigmatising, deficit-based language and approaches. Instead, it has started to focus on the topics that really matter to autistic people. This can be seen with the emergence of more autistic lead researchers, as well as some brilliant examples of participatory approaches within research practice.”

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Accelerating Science to Improve Early Autism Screening

April 23, 2024 • Feature Story • 75th Anniversary

At a Glance

Autism is a neurodevelopmental disorder that affects how people interact, communicate, and learn.
Making early autism screening part of routine health care helps connect families to support and services as early as possible.
Despite American Academy of Pediatrics guidelines, only a small fraction of pediatricians reported screening for autism at well-child visits.
NIMH-supported efforts to close the gap between science and practice have yielded key insights into effective strategies for expanding early autism screening.
Researchers are identifying new tools for detection, new models for delivering services, and new strategies for embedding early autism screening and rapid referral into routine health care.

As many parents of young children know all too well, visits to the pediatrician typically involve answering a series of questions. Health care providers may ask about the child’s eating and sleeping habits or about their progress toward walking, talking, and many other developmental milestones. Increasingly, they’re also asking questions that could help identify early signs of autism.

Autism is a neurodevelopmental disorder that affects how people interact, communicate, behave, and learn. It is known as a “spectrum” disorder because there is wide variation in the type and severity of symptoms people experience.

Today, thanks to research focused on embedding routine screening in well-baby checkups, the early signs of autism can be identified in children as young as 12–14 months. These efforts, many supported by the National Institute of Mental Health (NIMH), show that making early autism screening part of routine health care can have a significant impact on children and families, helping connect them to support and services as early as possible.

“This progress wasn’t inevitable or linear,” explains Lisa Gilotty, Ph.D., Chief of the Research Program on Autism Spectrum Disorders in the Division of Translational Research at NIMH. “Rather, it’s part of an evolving story that reflects the persistent, collective efforts of researchers and clinicians working to translate science into practice.”

Identifying the disconnect

The modern concept of autism as a neurodevelopmental disorder first emerged in the 1940s and coalesced into a diagnostic label by the 1980s. Diagnostic criteria evolved over time and, by the early 2000s, clinicians had evidence-based tools they could use to identify children with autism as early as 36 months. At the same time, evidence suggested that parents may notice signs even earlier, in the child’s second year of life.

“Reducing this gap—between observable signs and later identification and diagnosis—became an urgent target for researchers in the field,” said Dr. Gilotty. “The research clearly showed that kids who were identified early also had earlier access to supports and services, leading to better health and well-being over the long term.”

Researcher Diana Robins, Ph.D. , then a doctoral student, wondered whether an evidence-based early screening tool might help close the gap. With support from NIMH , Robins and colleagues developed the Modified Autism Checklist for Toddlers (M-CHAT) , which they introduced in 2001. They aimed to provide pediatricians with a simple screening measure that could identify children showing signs of autism as early as 24 months.

The science behind early screening continued to build and gain momentum over the next few years. By the mid-2000s, researchers were exploring the possibility of using various developmental screening tools—such as the Communication and Symbolic Behavior Scales, First Year Inventory, and Ages & Stages Questionnaires—to identify early signs of autism.

A young adult working on a computer gear with the text “Adults on the autism spectrum can benefit from services and supports that improve health and well-being across the lifespan.” The link points to nimh.nih.gov/autism.

The growing body of evidence did not go unnoticed. In 2006, the American Academy of Pediatrics (AAP) issued evidence-based guidelines recommending autism-specific screening for all children at the 18-month visit. In a later update, they recommended adding another autism-specific screening at the 24-month visit, recognizing that some children may start showing signs a bit later in development.

To the research community, these new guidelines signified a huge step forward for science-based practice. But this sense of progress was soon dashed by reality.

When researchers actually surveyed health care providers, they found that very few knew about or followed the AAP guidelines. For example, in a 2006 study , 82% of pediatricians reported screening for general developmental delays, but only 8% reported screening for autism. Most of the pediatricians said they weren’t familiar with autism-specific screening tools, and many also cited a lack of time as a significant barrier to screening.

The disconnect between science and practice prompted concern in the research community. A series of conversations in scientific meetings and workshops led to a crystallizing moment for the staff at NIMH.

“There was a period of several years in which researchers would go off and do unfunded work and then bring it back to these meetings and say, ‘This is what I've been working on,’” said Dr. Gilotty. “It was an impetus for those of us at NIMH to say, ‘We’re going to do something about this.’”

Bridging the gap

Gilotty worked with colleagues Beverly Pringle, Ph.D., and Denise Juliano-Bult, M.S.W., who were part of NIMH’s Division of Services and Intervention Research (DSIR) at the time, to synthesize several file drawers’ worth of different measures, meeting notes, and research papers and distill them into an NIMH funding announcement.

The announcement, issued in 2013, focused on funding for autism services research in three critical age groups: toddlers , transition-age youth , and adults . NIMH ultimately funded five 5-year research projects that specifically examined screening and services in toddlers. The projects focused on interventions that emphasized early screening and connected children to further evaluation and services within the first two years of life.

In 2014, Denise Pintello, Ph.D., M.S.W., assumed the role of Chief of the Child and Adolescent Research Program in DSIR. She directed the research portfolio that included these projects, which sparked an idea:

“It was such an exciting opportunity to connect these researchers because the projects were all funded together as a cluster,” she said. “I thought, ‘Let’s encourage these exceptional researchers to work closely together.’”

At NIMH’s invitation, the researchers on the projects united to form the ASD Pediatric, Early Detection, Engagement, and Services (ASD PEDS) Research Network. Although the ASD PEDS researchers were using different research approaches in a range of settings, coming together as a network allowed them to share knowledge and resources, analyze data across research sites, and publish their findings together . The researchers also worked together to identify ways that their data could help address noticeable gaps in the evidence base.

Building on the evidence

Together, the ASD PEDS studies have screened more than 109,000 children, yielding critical insights into the most effective strategies for expanding early autism screening.

For example, an ASD PEDS study led by Karen Pierce, Ph.D. , showed the effectiveness of integrating screening, evaluation, and treatment (SET) in an approach called the Get SET Early model.

Illustration of the steps in the Get SET Early model

Working with 203 pediatricians in San Diego County, California, Pierce and colleagues devised a standardized process that the providers could use to screen toddlers for autism at their 12-, 18-, and 24-month well-child visits. The researchers also developed a digital screening platform that scored the results automatically and gave clear guidelines for deciding when to refer a child for further evaluation.

These improvements boosted the rate at which providers referred children for additional evaluation and sped up the transition from screening to evaluation and services. The study also showed that autism can be identified in children as young as 12–14 months old, several years earlier than the nationwide average of 4 years.

This and other studies showed that incorporating universal early screening for autism into regular health care visits was not only feasible but effective. Working closely with health care providers allowed researchers to build trust with the providers and address their concerns.

“There is this sense that if you sit down and really talk with pediatricians, you can bring them into the fold,” said Dr. Gilotty. “Once you get some key people, you get a few more and a few more, and then it becomes something that ‘everybody’ is doing.”

Meeting the need

At the same time, the ASD PEDS studies have also explored ways to reach families with young children outside of primary care settings. Numerous studies have shown that some families are much less likely to have access to early screening and evaluation, including non-English-speaking families, families with low household incomes, and families from certain racial and ethnic minority groups.

“Screening is most effective when everyone who needs it has access to it,” said Dr. Pintello. “Addressing these disparities is a critical issue in the field and NIMH’s efforts have prioritized focusing on underserved families.”

One way to accomplish this is to integrate standardized universal screening into systems that are already serving these families. For example, in one study , ASD PEDS investigators Alice Carter, Ph.D. , and Radley Christopher Sheldrick, Ph.D. , worked with the Massachusetts Department of Public Health to implement an evidence-based screening procedure at three federally funded early intervention sites.

The researchers developed a multi-part screening and diagnosis process that included both clinicians and caregivers as key decision-makers. They hypothesized that this standardized process would minimize procedural variations across the early intervention sites and help to reduce existing disparities in ASD screening and diagnosis.

The results suggested their hunch was correct. All three study sites showed an increase in the rate of autism diagnosis with the new procedure in place, compared with other intervention sites that served similar communities. Importantly, the standardized procedure seemed to address existing disparities in screening and diagnosis. The increased rate of diagnosis observed among Spanish-speaking families was more than double the increase observed among non-Spanish-speaking families.

Looking to the future

Researchers are continuing to explore the best ways to put existing evidence-based screening methods into practice. At the same time, NIMH is also focused on research that seeks to develop new and improved screening tools. Evidence from neuroimaging and eye tracking studies suggests that, although the age at which observable features of autism emerge does vary, subtle signs can be detected in the first year of life. NIMH is supporting a suite of projects that aim to validate screening tools that can be used to identify signs of autism before a child’s first birthday.

“In other words, are there measures we can use to identify signs even before parents and clinicians begin to notice them?” explained Dr. Gilotty. “This is the critical question because the earlier kids are identified, the earlier they can be connected with support.”

These projects leverage sophisticated digital tools to detect subtle patterns in infant behavior. For example, researchers are using technology to identify patterns in what infants look at, the vocalizations they make, and how they move. They’re using technology to examine synchrony in infant–caregiver interactions. And they’re developing digital screening tools that can be administered via telehealth platforms.

The hope is that new tools identified and validated in this first stage will go on to be tested in large-scale, real-world contexts, reflecting a continuous pipeline of research that goes from science to practice.

“As a result of targeted research funded by NIMH over the last 10 years, we are seeing new tools for detection, new models for delivering services, and new strategies for embedding early screening and rapid referral into routine health care,” said Dr. Pintello.

“I feel like it’s just the beginning of the story—we are just now seeing the impact of bringing science-based tools and practices into the hands of health care providers. Over the next few years, we hope that ongoing efforts to bridge science and practice will help us meet the unique needs of children at the exact time that they need services.”

Publications

Broder Fingert, S., Carter, A., Pierce, K., Stone, W. L., Wetherby, A., Scheldrick, C., Smith, C., Bacon, E., James, S. N., Ibañez, L., & Feinberg, E. (2019). Implementing systems-based innovations to improve access to early screening, diagnosis, and treatment services for children with autism spectrum disorder: An Autism Spectrum Disorder Pediatric, Early Detection, Engagement, and Services network study. Autism , 23 (3), 653–664. https://doi.org/10.1177/1362361318766238

DosReis, S., Weiner, C., Johnson, L., & Newschaffer, C. (2006). Autism spectrum disorder screening and management practices among general pediatric providers. Journal of Developmental and Behavioral Pediatrics , 27 (2), S88–S94. https://doi.org/10.1097/00004703-200604002-00006

Eisenhower, A., Martinez Pedraza, F., Sheldrick, R. C., Frenette, E., Hoch, N., Brunt, S., & Carter, A. S. (2021). Multi-stage screening in early intervention: A critical strategy for improving ASD identification and addressing disparities. Journal of Autism and Developmental Disorders, 51 , 868–883. https://doi.org/10.1007/s10803-020-04429-z

Feinberg, E., Augustyn, M., Broder-Fingert, S., Bennett, A., Weitzman, C., Kuhn, J., Hickey, E., Chu, A., Levinson, J., Sandler Eilenberg, J., Silverstein, M., Cabral, H. J., Patts, G., Diaz-Linhart, Y., Fernandez-Pastrana, I., Rosenberg, J., Miller, J. S., Guevara, J. P., Fenick, A. M., & Blum, N. J. (2021). Effect of family navigation on diagnostic ascertainment among children at risk for autism: A randomized clinical trial from DBPNet. JAMA Pediatrics , 175 (3), 243–250. https://doi.org/10.1001/jamapediatrics.2020.5218

Pierce, K., Gazestani, V., Bacon, E., Courchesne, E., Cheng, A., Barnes, C. C., Nalabolu, S., Cha, D., Arias, S., Lopez, L., Pham, C., Gaines, K., Gyurjyan, G., Cook-Clark, T., & Karins, K. (2021). Get SET Early to identify and treatment refer autism spectrum disorder at 1 year and discover factors that influence early diagnosis. The Journal of Pediatrics, 236 , 179–188. https://doi.org/10.1016/j.jpeds.2021.04.041

Robins, D. L., Fein, D., Barton, M. L., & Green, J. A. (2001). The Modified Checklist for Autism in Toddlers: An initial study investigating the early detection of autism and pervasive developmental disorders. Journal of Autism and Developmental Disorders , 31 , 131–144. https://doi.org/10.1023/A:1010738829569

Sheldrick, R. C., Carter, A. S., Eisenhower, A., Mackie, T. I., Cole, M. B., Hoch, N., Brunt, S., & Pedraza, F. M. (2022). Effectiveness of screening in early intervention settings to improve diagnosis of autism and reduce health disparities. JAMA Pediatrics , 176 (3) , 262–269. https://doi.org/10.1001/jamapediatrics.2021.5380

NIMH Health Information Page: Autism Spectrum Disorder
NIMH Brochure: Autism Spectrum Disorder
NIMH Statistics Information: Autism Spectrum Disorder (ASD)
NLM MedlinePlus: Autism Spectrum Disorder
HHS Interagency Autism Coordinating Committee

Awareness of Autism Spectrum Disorder Among Population of Kazakhstan

Original Article
Published: 24 April 2024

Cite this article

Sandugash Kurmanalina 2 ,
Aizhan Samambayeva 1 , 3 ,
Nazgul Akhtayeva 1 , 2 ,
Laura Kozhageldiyeva 1 &
Lyazzat Kosherbayeva ORCID: orcid.org/0000-0001-8376-4345 1 , 2 , 4

In recent years, an abundance of research has substantiated the escalating prevalence of Autism Spectrum Disorder (ASD) on a global scale. The aim to assess the level of awareness regarding ASD among the Kazakhstan population, as well as their readiness to offer help to individuals affected by ASD.

A cross-sectional study was conducted encompassing individuals aged 18 years and above, using both the Russian and Kazakh languages. The survey was administered through Google Forms during April to June 2023. The link to survey was disseminated through WhatsApp chats of different social groups, including primary care specialists (general practitioners and nurses), and educators from primary and secondary schools from all 17 regions of Kazakhstan, spanning urban and rural areas. 410 participants took part in the survey in total. Statistical significance will be defined as p -values < 0.05.

Individuals aged 25 and above, who are both educated and employed, exhibit a greater awareness of ASD compared to other demographic groups. A low proportion of respondents (18.3%) demonstrated familiarity with the key symptoms of ASD as well as on its causes. Furthermore, it’s noteworthy that the primary resource for acquiring information about ASD was the internet for both of these regions.

Low awareness on ASD symptoms and treatment methods was identified in both areas. There is a need to develop activities to increase the public awareness on ASD, including knowledge on early symptoms of ASD and facilities that address the needs of people on the ASD and their families.

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This research has been funded by the Science Committee of the Ministry of Science and Higher education of the Republic of Kazakhstan (Grant No. BR18574199 «Integrating children with autism spectrum disorder into the social and educational environment based on comprehensive support: challenges and benefits»).

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All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Sandugash Kurmanalina, Aizhan Samambayeva, Nazgul Akhtayeva, Lyazzat Kosherbayeva, Laura Kozhageldiyeva. The first draft of the manuscript was written by Nazgul Akhtayeva, Laura Kozhageldiyeva, Sandugash Kurmanalina, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

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Correspondence to Lyazzat Kosherbayeva .

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Kurmanalina, S., Samambayeva, A., Akhtayeva, N. et al. Awareness of Autism Spectrum Disorder Among Population of Kazakhstan. J Autism Dev Disord (2024). https://doi.org/10.1007/s10803-024-06350-1

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Autism Spectrum Disorder in 2023: A Challenge Still Open

Annio posar.

1 IRCCS Istituto delle Scienze Neurologiche di Bologna, UOSI Disturbi dello Spettro Autistico, Bologna, Italy

2 Department of Biomedical and Neuromotor Sciences, Bologna University, Bologna, Italy

Paola Visconti

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In this paper, we provide an update on autism spectrum disorder (ASD), including epidemiology, etiopathogenesis, clinical presentation, instrumental investigations, early signs, onset patterns, neuropsychological hypotheses, treatments, and long-term outcome. The prevalence of this condition has increased enormously over the last few decades. This increase prompted a search for possible environmental factors whose effects would add up to a genetic predisposition leading to the development of autism. But the genetic and environmental variables involved are extremely numerous, and conclusive data regarding the etiopathogenesis are still far away. Assuming that a well-defined etiology is still found today only in a minority of cases, numerous pathogenetic mechanisms have been hypothesized. Among these, we mention oxidative stress, mitochondrial dysfunction, alteration of the intestinal microbiota, immune dysregulation, and neuroinflammation. These pathogenetic mechanisms could alter epigenetic status and gene expression, finally leading to ASD. Inherent in the term spectrum is the great clinical heterogeneity of this condition, mainly due to the frequent comorbidity that characterizes it. The earlier the diagnosis is made and the earlier psychoeducational treatment begins, the better the prognosis. In this sense, the role of pediatricians can be decisive in making children with signs suggestive of autism undergo a specialist diagnostic course. The development of increasingly advanced cognitive-behavioral educational techniques has considerably improved the prognosis of affected individuals, even though only a small minority of them come off the autistic spectrum. Pharmacological therapies are used to treat comorbidities. During childhood, the most important prognostic factor for long-term outcome seems to be intellectual functioning.

Introduction

According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), autism spectrum disorder (ASD) is an early-onset, mostly lifelong condition characterized by persisting deficits in social-communication skills (including social-emotional reciprocity, nonverbal communication, and developing/maintaining relationships) and restricted, repetitive behaviors (including stereotypies, insistence on sameness, highly restricted and fixated interests, and sensory abnormalities). Symptoms are present early in development and cause significant impairments in social and occupational functioning. ASD symptoms are not better explained by intellectual disability or global developmental delay, and this is a very important concept in order to avoid confusing these conditions. However, ASD often co-occurs with intellectual disability; comorbid diagnoses of ASD and intellectual disability are possible only when social communication skills are lower than expected in relation to the general developmental level. According to DSM-5, 3 levels of severity of ASD have been established: level 1 (requiring support), level 2 (requiring substantial support), and level 3 (requiring very substantial support). 1 The choice made in the DSM-5 to cancel the subdivision into the 5 diagnostic categories established by the DSM-IV (autistic disorder, Rett’s disorder, childhood disintegrative disorder, Asperger’s disorder, and pervasive developmental disorder not otherwise specified), 2 unifying everything under the term ASD, 1 has not been without criticism, and it is hoped that it will be corrected in the next edition of the DSM. 3 Despite various attempts to find a biological marker, today, the diagnosis of ASD is still based solely on clinical criteria. 1

From a historical perspective, the first reports of children with autism have been till today attributed by most authors to Leo Kanner (1943) 4 and Hans Asperger (1944), 5 but in reality, the first to describe this condition in a scientific journal was a woman, Grunya Efimovna Sukhareva, who in 1926 reported 6 boys with autism (which today would be defined “high functioning”), providing a lot of clinical details, including sensory abnormalities, 6 , 7 which acquired their proper weight only in the DSM-5’s description of ASD. 1

As concerns ASD etiopathogenesis, while in the past the psychogenetic theories prevailed, today we know that ASD is a condition with a neurobiological basis. The etiology is multifactorial and is characterized by an interaction between genetic and environmental factors. 8

In this narrative review, we aim to provide an update about this condition, considering epidemiology, etiopathogenesis, clinical presentation, instrumental investigations, early signs and onset patterns, neuropsychological hypotheses, treatments, and long-term outcome.

Epidemiology and Etiopathogenesis of Autism Spectrum Disorder

According to the most recent epidemiological studies carried out in the United States, ASD recurs in 1 in 36 children at age 8, and it is about 4 times more frequent among males than females. 9 The prevalence of this condition has increased enormously over the last few decades; This increase would be to some extent apparent as there is now greater awareness of this condition, but it would be largely real. 10 This last aspect prompted a search for possible environmental factors whose effects would add up to a genetic predisposition leading to the development of autism. 8 Indeed, early exposure, in particular during pregnancy and in the first year of extrauterine life, to air pollutants (especially particulate matter with an aerodynamic diameter ≤2.5 μm) 11 or to agricultural pesticides 12 is associated with a higher risk for ASD.

But the genetic and environmental variables involved are extremely numerous, and conclusive data regarding the etiopathogenesis of ASD are still far away. Assuming that a well-defined etiology is still found today only in a minority of cases with ASD, numerous pathogenetic mechanisms have been hypothesized and supported by interesting data. Among these mechanisms, we mention oxidative stress, 13 , 14 mitochondrial dysfunction, 15 alteration of the gut microbiota (see the wide variety of microorganisms colonizing the human gastrointestinal tract), 16 immune dysregulation, 17 and neuroinflammation. 14 Note that these mechanisms are not mutually exclusive but could act in synergy with each other, leading to the development of ASD. 8 In reality, the true meaning of the alterations to these mechanisms has yet to be understood. Let us take the example of the gut microbiota: are the alterations found in subjects with ASD the cause of the disorder or its consequence, taking into account the food selectivity they often display and their propensity to bring inedible objects to their mouths? 18

A key to understanding how these pathogenetic mechanisms could act is given by the concept of epigenetics. Epigenetics is a crucial gene regulation system based on chemical changes in DNA and histone proteins without altering the sequence of DNA. The abovementioned pathogenic mechanisms could alter epigenetic status and gene expression, finally leading to ASD. Also, some environmental factors, including heavy metals (e.g., lead) and endocrine disrupting chemicals (e.g., pesticides), could directly or indirectly modify the epigenetic status. 19 , 20

However, the fact that, according to the most recent studies, the prevalence of ASD in males is confirmed (male-to-female ratio = 3.8) 9 suggests that, in the etiopathogenesis of the disorder, genetics still outweighs acquired factors.

We dedicate a last mention to the so-called syndromic autism. It describes the minority of individuals with ASD who present comorbid features and/or a putative genetic etiology. This concept has been deeply criticized, also because it has no single definition, and is probably destined to fall into disuse. 21 We have preferred not to use it in this review.

Heterogeneity of Autism Spectrum Disorder Clinical Presentation

Inherent in the term “spectrum” is the great clinical heterogeneity of this condition. The range of possible impairments in ASD goes from severe disability with almost complete absence of personal autonomy to a so-called high-functioning condition in which the individual can have normal or even higher-than-normal intellectual functioning and can play a role of responsibility in the social context. 3 The considerable heterogeneity of the ASD clinical picture is mainly due to the frequent comorbidity that characterizes it. Intellectual disability, attention-deficit/hyperactivity disorder (ADHD), insomnia, mood disorders, and epilepsy are just some of the possible neuropsychiatric comorbidities. Also, medical comorbidities, in particular gastroenterological ones (including celiac disease), can complicate the clinical picture of individuals with ASD. 3 , 22

Another element of clinical heterogeneity is given by the possible presence of sensory abnormalities that are very often found in subjects with ASD, especially in the first years of life, leading to a distortion of the perception of reality and representing the possible key to understanding many of their atypical behaviors (e.g., attraction to artificial lights, annoyance for crowded environments, food selectivity) and also of the so-called challenging behaviors (e.g., auto- or hetero-aggressiveness, throwing things, tantrums). 23 An impairment of multimodal integration (i.e., the ability to integrate information coming from different sensory channels: visual, auditory, somatosensory, etc.) has also been implicated. 23 In this regard, functional magnetic resonance imaging studies have highlighted elements that suggest an alteration of brain long-range connectivity in individuals with ASD, 24 which could lead precisely to an impairment of this integration capacity.

Instrumental Investigations in Individuals with Autism Spectrum Disorder

From the point of view of the etiological diagnosis, nowadays it seems essential to carry out the following investigations: hearing evaluation through behavioral audiometry or, if not possible, through an auditory brainstem response (ABR) test; genetic tests (array-based comparative genomic hybridization, or array CGH; in males, molecular search for fragile X syndrome; and in some cases, next generation sequencing); electroencephalogram possibly also during sleep, even in the absence of overt clinical seizures, in particular to rule out electroclinical conditions such as continuous spikes and waves during slow sleep (CSWS), which are potentially treatable with a drug therapy. 25 Common neuroimaging techniques, and in particular brain magnetic resonance imaging, are usually normal or at most show nonspecific findings; 26 therefore, they should be performed only in some cases, including: a clinical history characterized by marked and persisting neurocognitive deterioration; the presence of clear neurological signs (macrocrania or microcrania, cerebral palsy, dystonia, etc.); a genetic condition that notoriously predisposes to a brain malformation; epileptic seizures; an electroencephalogram showing relevant alterations such as focal paroxysmal abnormalities or asymmetries of the electrogenesis. At the conclusion of the etiological workup, genetic counseling is recommendable, even though instrumental investigations have not shown any significant results, aiming also at calculating the risk of recurrence of ASD (or other neurodevelopmental disorders) in the family.

Early Signs and Onset Patterns of Autism Spectrum Disorder

A reasonable diagnostic suspicion of ASD can usually be placed around 18 months of age, while a definitive diagnosis of ASD can commonly be made within 3 years of age. There are several tools for early screening of ASD; one of the most used is still today the Modified Checklist for Autism in Toddlers (M-CHAT). 27 To make the final diagnosis of ASD as objective as possible, standardized assessment tools are used today, such as the Autism Diagnostic Observation Schedule—Second Edition (ADOS-2), 28 and Autism Diagnostic Interview—Revised (ADI-R). 29 In this context, the time factor is very important. 27 The earlier the diagnosis is made and the earlier psychoeducational treatment begins, the better the prognosis. 30 In this sense, the role of pediatricians can be decisive in making children with signs suggestive of ASD undertake a specialist diagnostic course. Nowadays, several ASD screening tests for pediatricians are available, none of which, however, is without setbacks; they represent useful tools but should not be considered the only source of information in order to decide whether to start a diagnostic workup in a center specialized in neurodevelopmental disorders. For this purpose, it is very important to pay attention to all possible warning signs reported by parents as well as to directly observe the behavior of the child. 27 In infants, even before a possible speech delay becomes evident, the most indicative signs of ASD are strictly related to social-communication skills as follows: looking at the faces of others; orienting to name; presence of joint attention (i.e., the ability to share focus with others on 1 object); affect sharing; and imitation. 31 When some of these behaviors are lacking, a specific assessment is mandatory. Further, let us not forget that the core signs of autism are not infrequently preceded by signs of impaired motor development, 32 such as motor delay, mostly slight, 33 hypotonia, 34 walking on tiptoes, and/or clumsiness. 1 Therefore, the presence of an early motor impairment, even if mild, should be included among the first signs that could lead to a timely ASD diagnosis. 32

Several different ASD onset patterns have been reported. The most frequent are the “early-onset” pattern, characterized by social-communication deficits developing in the first year or so, and the “regressive autism”, characterized by an onset of autistic signs in the second year, mostly at 16-20 months, associated with a loss of social-communication skills. Another onset pattern is characterized by mixed features: first delay and later loss of social communication skills. There is also an onset pattern named “developmental plateau”, characterized first by normal social development and/or non-specific abnormalities (involving also feeding or sleep), and later by a lack of new acquisitions on the socio-communicative level. 31

Neuropsychological Hypotheses About Autism Spectrum Disorder

From a neuropsychological point of view, 3 main hypotheses have been developed to explain cognitive dysfunction in individuals with ASD. 35 First, failure of theory of mind refers to the inability to interpret the behaviors of others based on their feelings and beliefs and to identify their intentions and emotions, leading to social communication impairments. 36 , 37 Second, there is the hypothesis of a deficit of executive functions, which are a series of cognitive processes including attention, working memory, inhibitory control, planning, and cognitive flexibility that are crucial for adaptive behavior and social cognition skills. 38 , 39 Third, weak central coherence theory refers to the propension of individuals with ASD to use an information processing style that is excessively detail-oriented, 40 , 41 leading to an impairment of social interactions for which an adequate integration of diverse elements such as voice, mimicry, gestures, and environmental context is necessary. 41 This theory partly overlaps with what was mentioned above regarding the multimodal integration deficit and underlines once again the fact that, although visuospatial skills and attention to detail represent strengths in these subjects, when they have to integrate this type of stimuli with other types of stimuli, they may encounter great difficulty. 35

These 3 theories are not mutually exclusive. Each of them is able to explain a part of the autistic symptomatology, but none is able to give a complete explanation. 35

Treatments for Autism And Longterm Outcome

The development of increasingly advanced cognitive-behavioral educational techniques, of which the best known belong to applied behavior analysis (ABA) therapy, has considerably improved the prognosis of affected individuals. Applied behavior analysis utilizes the principles of psychological learning theory in order to modify the behaviors usually present in subjects with ASD. In the 1970s, Ole Ivar Lovaas developed a method that was based on Burrhus Frederic Skinner’s operant conditioning theory, with the aim of changing behaviors and improving social interactions in children with ASD. During the past 60 years, ABA has changed considerably, evolving into many treatment practices, with the aim of dealing with the problems of individuals with ASD in all functioning domains, such as cognition, social skills, language, daily living skills, and challenging behaviors. 42 Today, only a small minority of these subjects come off the autistic spectrum, but almost all can improve considerably by increasing their level of autonomy. 43 After the diagnosis, psychoeducational and often emotional support are very important for parents. Several other interventions are used extensively around the world for children with ASD, although the evidence for their effectiveness does not match that of ABA. Occupational therapy interventions, in particular those using new technologies such as the computer, have shown positive effects on activities of daily living and social skills. 44 In the contest of occupational therapy, sensory integration interventions, in particular when using the principles proposed by Anna Jean Ayres (e.g., tailoring challenges to assure that they are slightly beyond the current performance level of the child), showed positive effects on participation in daily-life activities and routines. 45 Floortime, a relationship-based therapy, has shown that it can improve communication, emotional functioning, and daily living skills in children with ASD. 46

A pharmacological therapy for the core symptoms of autism does not exist. However, pharmacological therapies are used to treat comorbidities: for example, melatonin or (if not effective) niaprazine for sleep disorders, antiseizure drugs for epilepsy (the choice of drugs depends mainly on the type of epilepsy and possible behavioral undesirable effects), and methylphenidate for ADHD. In addition, drug therapy is used to treat challenging behaviors when cognitive-behavioral interventions have not produced adequate results. In these situations, atypical neuroleptics (e.g., risperidone and aripiprazole) are currently the most commonly often used drugs. Indeed, based on a recent systematic review and meta-analysis of antipsychotic medications in autism, there is some evidence for favorable effects of risperidone and aripiprazole on irritability and agitation in children with ASD. 47 However, we wish to underline that the use of pharmacotherapy should be resorted to only when there is a real need and, if possible, for limited periods of time.

Based on the hypothesis that children with ASD have increased levels of systemic heavy metals interfering with their neurodevelopment and leading to autism, in many of these patients, chelation therapy has been attempted using an agent that binds to the excess heavy metal, causing its excretion. Yet, clinical trials of this therapy in ASD are lacking. Based on literature data, in ASD there is no evidence for the effectiveness of chelation therapy, which is associated with very severe and potentially lethal side effects such as cardiac arrhythmias and hypocalcaemia. 48

Interesting findings are emerging regarding diet therapy. One recent systematic review and meta-analysis suggests that diet therapies (including ketogenic diets, gluten-free diets, and gluten-free and casein-free diets), may have favorable effects even on ASD core symptoms. However, more high-quality clinical trials are needed. 49

During childhood, the most important prognostic factor for long-term outcome seems to be intellectual functioning: the higher the intelligence quotient, the better the long-term evolution. But also, the presence of verbal language (although atypical) within 5-6 years of life appears to be a favorable prognostic factor. 43 Unfortunately, approximately 25%-30% of affected individuals develop very little to no verbal skills; they are called “minimally verbal” and usually show a poor long-term outcome. The severe deficit of communication skills (verbal and nonverbal) is very often the basis of the aforementioned challenging behaviors. Also for this reason, providing early non-speaker individuals with alternative means of communication, such as augmentative and alternative communication, is of paramount importance. 50

Conclusions

For professionals who deal with ASD, it is a frustrating situation to witness the growth in the prevalence of this condition without knowing exactly the reasons and consequently without having the most suitable tools to counter it, despite all the knowledge about the neurobiology of ASD that has accumulated over the last years. Today, however, it seems clear that genetic factors alone are unable to explain this phenomenon that some have called the “autism epidemic.” Therefore, in recent years, growing attention has been paid to the environmental factors that can trigger the mechanisms leading to the development of ASD. For these factors, actions of prevention could be very useful, but they require potentially unpopular political decisions whose possible effectiveness could be evaluated only in the long term. Unfortunately, nowadays we still know too little about environmental factors to undertake fully effective prevention actions.

From the research perspective, perhaps to better understand why a child develops an ASD, it would be interesting to study not only what is possibly missing in him/her (e.g., chromosomal deletion detected by the array CGH) or what malfunctions (e.g., focal paroxysmal abnormalities on the electroencephalogram), but also the existing possible protective factors, for example, in the genetic heritage of typically developing individuals and which would be missing in subjects with ASD. This research approach could provide very useful information in the future, but it would clearly be very complicated to put into practice.

The increasing prevalence of ASD clearly has a very negative impact on the public health service, due to the large human and material resources that must be employed to address the problem on the diagnostic and therapeutic sides. However, it should be clear that what we do for today’s autistic children will inevitably affect tomorrow’s autistic adults. Spending many resources on treatments for individuals with ASD in their developmental age in order to give them as much personal autonomy as possible, for example in terms of communication skills, is an investment for the future as it reduces the risk of challenging behaviors arising in adolescence or adulthood, which in turn involve the prolonged use of large resources.

Funding Statement

This study received no funding.

Peer-review: Externally peer-reviewed.

Author Contributions: Concept, Design, Writing, Literature Search – A.P.; Concept, Supervision, Critical Review – P.V.

Acknowledgment: The authors would like to thank Cecilia Baroncini for help in editing the text.

Declaration of Interests: The authors have no conflict of interest to declare.

Autism often diagnosed later in life for females

Editor's Note: The following is part of a class project originally initiated in the classroom of Ball State University professor Adam Kuban in fall 2021. Kuban continued the project this spring semester, challenging his students to find sustainability efforts in the Muncie area and pitch their ideas to Ron Wilkins, interim editor of The Star Press, Journal & Courier and Palladium-Item. This spring, stories related to health care will be featured.

Going through school, Erin Geddes felt like she slipped through the cracks.

The now 41-year-old wife and mother often felt overlooked in her childhood in California. She described her experiences as trying to fit in but couldn’t. She knew she had an advanced emotional maturity compared to her peers and believed she had the smarts. However, it did not translate into grades.

“The schools didn't really measure my giftedness,” said Geddes, who now lives in Indianapolis.

During the pandemic, Geddes did some of her own personal research and realized why she always felt left out — she was autistic.

Autism is a neurological disorder that affects how a person interacts with the world around them, according to the Center of Disease Control and Prevention .

Common stereotypes show autism as mainly affecting boys. In fact, boys diagnosed as autistic are at a 4 to1 ratio compared to girls, according to the National Institute of Mental Health . However, autism might be underdiagnosed in women, especially adult women.

A study published in 2020 in the “Journal of Autism and Developmental Disorders” found that almost 5.5 million American adults are autistic, which is equivalent to the population of South Carolina.

More adult women have been diagnosed on the autism spectrum in recent years, however, as women present their autism differently than men. A 2022 study in the “Children” journal concluded that the true female ratio could be 3 men to every 4 women, and that 80 percent of females remain undiagnosed with autism at the start of adulthood.

Kristin McCoy, executive vice president of intensive intellectual and developmental disability services at Damar Services, said that it can be more challenging for people who are assigned female at birth to be diagnosed as autistic in general. Damar focuses on providing services to people with autism and other intellectual and developmental disabilities.

“Girls can be more skilled in kind of masking some of the social deficits,” McCoy said.

Traits of autism that can show in boys, according to the Mayo Clinic , include poor eye contact, having specific food preferences, developing specific routines and having odd moving patterns.

Some of these characteristics of autism in females include sensory sensitivity that can overstimulate an autistic person, difficulty to finish tasks, repetitive behaviors such as “stimming,” and difficulty understanding and responding social cues.

Stimming is the repetition of physical movements such as hand flapping or rocking.

McCoy also explained some of the characteristics related to autism could also be misdiagnosed as ADHD or that person could be considered more socially reserved than have social impairments that would meet the criteria for testing.

Geddes has some of these characteristics and said her masking these characteristics eventually led her to burnout and a mental breakdown.

“It just seemed like I would try so hard, and it just wouldn't change," Geddes said. "I was experiencing things that before I felt like I could handle OK, but it was just becoming harder.”

Eventually, she asked her mental-health provider for a referral for an autism diagnosis. After her diagnosis, Geddes said she was able to authentically present herself to everyone and not mask her autistic characteristics and give herself grace for her own personal shortcomings.

A 2020 study in the “Autism” journal interviewed 11 autistic females about their experiences of being diagnosed as an adult. All participants reported moving toward a place of self-acceptance after their diagnosis with some saying it made sense of their identity as autistic people through learning more about autism.

The study also found that these autistic females had a new and increased sense of agency, allowing them to make sense of their own life experiences.

McCoy said that even though there are a lot of stereotypes, it is important for people with autism to remember that they are not different or less than anybody else.

“I think it's really critical that people recognize that they don't view it as a weakness because there's a lot of strength in a diagnosis,” McCoy said.

Since her diagnosis, all of Geddes’ children have been diagnosed with autism as well.

The experience has compelled her to write a children’s book to educate people about autism and neurodiversity in general. The book, titled “And That’s Okay: I’m Wired Differently,” is available through online retailers.

“I can identify with my kids and their struggles through academics and socially,” she said.

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Review Article
Open access
Published: 30 April 2020

Autism spectrum heterogeneity: fact or artifact?

Laurent Mottron ORCID: orcid.org/0000-0001-5668-5422 1 &
Danilo Bzdok 2 , 3

Molecular Psychiatry volume 25 , pages 3178–3185 ( 2020 ) Cite this article

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Autism spectrum disorders
Neuroscience

The current diagnostic practices are linked to a 20-fold increase in the reported prevalence of ASD over the last 30 years. Fragmenting the autism phenotype into dimensional “autistic traits” results in the alleged recognition of autism-like symptoms in any psychiatric or neurodevelopemental condition and in individuals decreasingly distant from the typical population, and prematurely dismisses the relevance of a diagnostic threshold. Non-specific socio-communicative and repetitive DSM 5 criteria, combined with four quantitative specifiers as well as all their possible combinations, render limitless variety of presentations consistent with the categorical diagnosis of ASD. We propose several remedies to this problem: maintain a line of research on prototypical autism; limit the heterogeneity compatible with a categorical diagnosis to situations with a phenotypic overlap and a validated etiological link with prototypical autism; reintroduce the qualitative properties of autism presentations and of current dimensional specifiers, language, intelligence, comorbidity, and severity in the criteria used to diagnose autism in replacement of quantitative “social” and “repetitive” criteria; use these qualitative features combined with the clinical intuition of experts and machine-learning algorithms to differentiate coherent subgroups in today’s autism spectrum; study these subgroups separately, and then compare them; and question the autistic nature of “autistic traits”

Social and non-social autism symptoms and trait domains are genetically dissociable

Varun Warrier, Roberto Toro, … Simon Baron-Cohen

Cortical signatures in behaviorally clustered autistic traits subgroups: a population-based study

Angeline Mihailov, Cathy Philippe, … Vincent Frouin

Autism spectrum disorder

Catherine Lord, Traolach S. Brugha, … Jeremy Veenstra-VanderWeele

Introduction

The heterogeneity of autism is now universally accepted, at the phenotypic level under the DSM-5 term “spectrum”, as well as at the imaged brain [ 1 ] and etiology [ 2 ] levels. The overarching pervasive developmental disorders (PDD) category of the DSM-IV initiated a deviation towards less prototypical presentations of autism. Asperger’s syndrome was considered to be autism without the requirement of language signs and PDD not otherwise specified as subthreshold autism of various types. The current DSM-5 definition of autism spectrum disorder (ASD) merged the PDD subgroups inter alia , due to their poor inter-judge reliability and instability over time [ 3 ]. Doing away with PDD not otherwise specified as a category, which was responsible for the considerable increase of reported prevalence at the time, but for which the criteria were insufficiently reliable, [ 4 ] was expected to increase the specificity of the categorical diagnosis [ 5 ].

The evolution of the DSM has been accompanied by a 20-fold increase in the reported prevalence of ASD over the last 30 years, reaching a current prevalence of more than 2% in the United States [ 6 ] (Fig. 1a ). The implementation of standardized retrospective [ 7 ] and observational diagnostic tools [ 8 ] in the diagnostic process has not limited this trend and may have even contributed to it in the clinical setting, possibly due to their lack of specificity towards other childhood psychiatric conditions [ 9 ] and the false sense of security they provide when someone “meets diagnostic criteria [ 10 ]”, despite clinical inconsistency with prototypical presentations.

a The change in autism prevalence over time, based on data from [ 65 , 66 , 67 ]. Methodologies may differ between studies. b The changes in group-level standardized mean differences between autism and control samples over time, as described by Rødgaard et al. (2019) [ 14 ]. A significant downwards temporal trend was observed in five of seven investigated constructs in autism. c The number of published studies investigating autistic traits in the normal population and for other clinical conditions, showing an eightfold increase during the last decade. d The number of published empirical studies performing research on autism, showing a fourfold increase during the last decade. (“ c ”,“ d ” source: Pubmed).

A single categorical diagnosis, which encompasses such heterogeneity of developmental history, intelligence, comorbidity, and severity, poorly contributes to the planning of intervention and educational services. What is common between intervention strategies supporting an adult with academic-level written and oral language and an intellectually disabled, syndromic autistic child with major self-injurious behaviors [ 11 ]?

In addition to the clinical consequences, these considerations also have important ramifications for conducting and interpreting research studies. Currently, the modest state of genetic [ 12 ] knowledge of non-syndromic autism and the polygenic heterogeneity across ASD subtypes [ 13 ] suggests that we may need to update our research targets and strategies. The effect sizes obtained from cognitive, EEG, and neuro-anatomical studies of autism decreased by up to 80% between 2000 and 2015 [ 14 ] (Fig. 1b ), even when accounting for sample size and quality. The cause of this trend is yet to be determined but likely includes a reduction in the deviation from the norm required to reach the threshold for a categorical diagnosis [ 15 ], and the poor specificity of current diagnostic criteria for extreme values of age, intelligence, and severity [ 16 ]. Other important factors that may contribute to this trend include the disappearance of differential exclusion diagnoses, as well as the absence of an “economy principle”, privileging the diagnosis which best explains the presented symptoms [ 17 ]. The presence of such “self-inflicted” heterogeneity plausibly distorts the autistic signal and negatively influences the ability to make replicable discoveries.

The wide-ranging disappearance of studies on differential diagnosis contrasts with the explosion of meta-analyses and systematic reviews (respectively less than 1/1000 vs. 3% of the autism literature in 2019). Most scientific knowledge of autism is obtained through condensing findings on an increasingly heterogeneous and decreasingly atypical population, without questioning the case ascertainment on which this knowledge is grounded. All research is carried out downstream of diagnostic criteria, little of it upstream. Sociologically, we are living in a time of rebalancing the traditional emphasis on stringent inclusion and exclusion criteria for clinical neuroscience studies. There is also growing interest in deriving insight from population and prospective cohorts with thousands of subjects [ 18 ]. As a necessary side effect of these developments in research trends, many autism-vs.-non-autism classification studies have become difficult to reproduce in these heterogeneous cohorts of unprecedented breadth [ 19 ]. We thus highlight the dilemma between the high predictive accuracies of preselected samples and much lower predictive accuracies of more naturally acquired subject samples [ 20 ]. In this context, the co-existence of qualitative and quantitative autism traits may have critical consequences for the future of single-patient predictions in precision psychiatry.

Confronting essentialist and nominalist views of autism

We are still uncertain about the entity of autism. It can either appear to have a natural basis (“essentialist” position) or as multi-determinant, for which unity is in the eye of the viewer or the vocabulary they use (“nominalist” position). Although we are able to recognize this clinical condition with good reliability, we are not yet very skilled at defining it in a specific way. We also know that the signs that characterize it are not always simultaneously present, and/or that they can appear to be attenuated, making delineation of the autism category difficult.

However, the two positions should still compete for the truth. The absence of a categorical limit and the multiplicity of aetiologies and risk factors reported previously [ 21 , 22 , 23 ] anticipate the current state of knowledge. To be able to determine whether autism has a natural basis or not, the two positions should be given equal weight, as the validity of either is still undecidable in the current state of autism diagnosis. This requires studying individuals who are very similar to each other to obtain biomarkers, then to search for these markers in attenuated phenotypes. This does not guarantee that we will find a single basis in primary biology. However, if we start from the spectrum as currently defined, it is clear that we will not find this single cause, if it exists.

DSM-5 criteria for autism may produce spurious heterogeneity

Combining nonspecific social and repetitive categorical criteria with four “open” specifiers (levels of intelligence, language, severity, and comorbidity), as well as all their possible combinations, can result in a vast array of ASD presentations. However, does such variability truthfully reflect diversity in cognition, the brain, and genes?

The quantitative nature and poor specificity of signs which, when combined, result in a categorical diagnosis

The categorical diagnosis of ASD is currently obtained by pass/fail scoring of seven signs (i.e., three social and four repetitive), mostly quantitative (e.g., less socially-oriented behaviors), rather than qualitative (those that can be recognized). These signs are inherently imprecise due to their quantitative/dimensional nature (how do we define a threshold for “lack of socialization?”) and open character (from… to….), leading to the bundling of a variety of phenotypes that are not specific to autism. For example, autistic gaze atypicality and an embarrassed look are qualitatively distinct, but both make it possible to positively score the A2 criterion, “Deficits in nonverbal communicative behaviors used for social interaction”. Conversely, a rapid initial gaze at faces, followed by the apparent absence of behavioral hallmarks for social reciprocity, would become more specific by the addition of qualitative dimensions [ 24 ]. Certain signs (B2, “rigidity”, and B4, “sensory”), which when associated allow one to reach the diagnostic threshold in the area of repetitive behaviors, are also observed in a large proportion of children with other neurodevelopmental and psychiatric disorders [ 25 , 26 ].

Indeterminate nature of the clinical specifiers

The four clinical specifiers of ASD were originally designed to account for the unavoidable heterogeneity of autistic presentation, for example, between nonverbal and hyper-verbal individuals, while preserving the category. These specifiers now exacerbate the heterogeneity of the individuals included in this spectrum, transforming the autism diagnosis into a category as vague as “intellectual disability” and “neurodevelopmental disorders”. A common characteristic of the four clinical specifiers is their dimensional, quantitative, and clinically nonspecific nature. Moreover, there are no constraints on how the qualitative properties of the seven criteria are modified according to the expression of each of the specifiers, which misses a major opportunity to increase specificity. For example, a dissociation between advanced knowledge of letters and numbers and poor pragmatic use of verbs would contribute qualitative information to a quantitative ‘’language” specifier [ 27 ].

Conceptual ambiguity favors heterogeneity

Two conceptual sources of imprecision may further contribute to the current heterogeneity of the autism spectrum: the belief that the clinical threshold for autism is necessarily arbitrary, and the acceptance of any identified neurogenetic or psychiatric condition as a comorbidity, combined with the absence of exclusion criteria or recommended differential diagnoses.

Is the clinical threshold arbitrary?

A major additional source of heterogeneity in the ASD spectrum is the lowering of the threshold for clinical significance required for the inclusion of individuals who are less different from typical individuals [ 15 ]. This escalation in flexibility is frequently justified by the consensus in autism research that clinical thresholds are necessarily arbitrary and/or do not reach reliability among clinicians. The corresponding justification is typically grounded on the philosophical tradition of questioning the status of “natural” boundaries [ 28 ]. The description of natural categories separated by objective boundaries has been, since Plato’s illuminating metaphor, compared with “carving nature at its joints”: a butcher does not question the natural boundaries of joints when preparing meat. In defense of the hypothetically arbitrary nature of autism boundaries, this analogy has been ironically transformed by likening the search for a categorical boundary for autism into “carving meatloaf at its joint [ 29 ]”. These “joints” were however visible when autism was initially discovered decades ago. However, they disappeared as an effect of the “grinding” of autistic phenotypes into symptoms or traits. The replacement of pattern-like recognition with the use of polythetic criteria in an effort to make such clinical recognition a reliable and objective process has failed. Heterogeneity has introduced itself into the spaces between clinical sub-prototypes and has been authorized by their common inclusion in an overarching, criteria-based category. Hence, the meatloaf “spectrum”.

Syndromic vs. non-syndromic autism

Although the reported increase in prevalence of autism-like syndrome in a limited number of identifiable neurogenetic syndrome (e.g., Fragile X, Williams syndrome) or identified copy-number variations (e.g., 16p11.2) is recognized, it has also been demonstrated that any neurodevelopmental condition accompanied by a certain degree of intellectual disability and behavioral issues increases the probability of satisfying certain autism criteria [ 30 ]. The syndromic/non-syndromic distinction has been questioned by some on the basis that today’s non-syndromic autistic presentations will be tomorrow’s syndromic ones, following new discoveries. Waiting for this promised land, the bundling of non-syndromic and syndromic autism assumes external validity for the entire spectrum of discoveries made in patients and animal models with an identified condition sometimes comorbid with autism-like presentations. However, this contention is not supported by the phenotypic dissimilarity between autism with and without penetrant de novo genetic variants [ 31 ], nor by the mechanistic differences between the strong effects of reliably identified de novo mutations, on the one hand, and the additive weak effects associated with common variants [ 13 , 32 ], on the other. In addition, the multiple mutations and pathogenic pathways associated with syndromic autism are only rarely/exceptionnaly [ 33 ] traced in non-syndromic autism.

Are “autistic traits” autistic?

The concept of an autistic trait and the demonstration that “autistic traits are continuously distributed throughout the general population [ 34 ]” through instruments such as the Autism Screening Questionnaire [ 35 ] and Social Responsiveness Scale [ 36 ] has led to the flowering of multiple studies associating autistic traits with nonmedical conditions (e.g., masculinity) [ 37 ], separate diagnoses (e.g., anorexia) [ 38 ], or in people exposed to a myriad of supposed etiological factors (e.g., cesarean birth) [ 39 ]. The increase in the number of such studies during the last decade has been twice as large as for the total number of empirical studies of autism (Fig. 1c,d ). Studies reporting autistic traits in a large number of psychiatric or neurological conditions consider them by default as autistic traits rather than socialization features associated with a particular, non-autistic condition. Are these “autistic traits” themselves autistic? The answer is “no” if they are extracted from the pattern they compose in combination with other traits. All striped animals are not tigers, and all stripes are not tiger stripes.

Disentangling potentially artifactual from genuine heterogeneity

There is, however, heterogeneity that plausibly belongs to the autism signal when the kinship between a prototypical clinical presentation and an altered version is biologically validated. Examples of this include developmental transformations, some (but not all) variations in presentation according to intelligence and language level, and the familial aggregation of autism subtypes.

Developmental transformation

Removing variation due to age by a de-confounding procedure that integrates the time course in the sign characteristic is likely to remove at least part of the heterogeneity introduced by one of the dominant sources of population variation [ 40 ]. However, the developmental transformation of autistic signs [ 41 ], while generally trending towards a smaller difference from typicality with age [ 42 ], is not a continuous process. Numerous signs in the area of repetitive behaviors and restricted interests present their own developmental course [ 43 ], such as, for example, “hand leading”, which is used by a child to nonverbally indicate what he wants. It therefore combines an atypical manner of requesting (positive for the “abnormal social approach” sign) with a specific language-specifier value (speechless plateau), nonverbal intelligence (in the normal range), and a certain age range (2–5 years). Similarly, hand flapping, lateral glances, the absence of overt joint attention, and even most self-injurious behaviors have a “golden age”. These considerations would justify the coupling of age of occurrence with specifier values, and qualitatively defined categorical signs, which could increase the capacity of the clinician to recognize an autistic feature.

Does familial aggregation of autism subtypes and other psychiatric diagnoses validate autism heterogeneity?

Studies of first-degree relatives of autistic people demonstrate an increased prevalence of cognitive, motor, and psychiatric differences relative to the general population [ 44 ]. Familial aggregation of multiple presentations encompassed under the autism spectrum category range from discrepant autism subtypes (e.g., with and without Speech Onset Delay (SOD) [ 45 ]) in siblings to subthreshold atypicalities or a “broader autism phenotype”. At its most extreme, there is a familial co-occurrence of conditions which minimally overlap with the autism phenotype and are clinically considered as differential diagnoses at the phenotypic level, such as specific language impairment [ 46 ], or as an unambiguously different type, such as mood disorders [ 47 ].

Such familial aggregation validates a certain mechanistic relationship between a prototypical and less prototypical presentation of autism. However, it should not result in encompassing any presentation with a trivial resemblance to autism under a “subthreshold” or “trait” dimension. The independence between genetic alterations and the resulting phenotype associated with them is a well-accepted trivial finding in behavioral genetics. For example, the 22q11.2 deletion syndrome shows variable penetrance and is associated with multiple, phenotypically unrelated psychiatric presentations [ 48 ]. In contrast, a minimal variation of the dominant social phenotype in any condition or in the typical population can still be labeled “autistic” [ 34 ], even in situations in which the relationship with the full-blown phenotype is unproven—another example of an unfounded “autism exception”.

Acknowledging the effect of artifactual heterogeneity in clinical settings and research programs

The decrease in effect-sizes in neurocognitive autism research over time is likely due to increased artifactual heterogeneity, which affects our ability to construct neurobiological models of autism. We propose that these problems may be mitigated by modifying the diagnostic criteria and prevalent research strategies.

Re-building autism subgroups from the recognition of its most prototypical forms

There is more information in the brains of autism experts than that provided by diagnostic instruments. Thus, new criteria should be built from such expertize by decomposing the phenotype of a prototypical population into the qualitative signs that contribute to recognizing autism, which do not coincide with the DSM signs. Experts recognize more reliably “frank” autism than any of the diagnostic instruments developed to operationalize this diagnosis using check-list criteria [ 49 ]. Importantly, this reliability was independent of age, IQ, and level of functioning. The top-down search for behaviors corresponding to criteria during a diagnostic process is intrinsically more inclusive that the bottom-up recognition of the behavioral patterns that such criteria are based on. Any forthcoming revision of the diagnostic criteria for autism should also restrict the current number of combinatorial possibilities of the clinical specifiers. Instead, it may be beneficial to associate specific combinations of values of these specifiers with specific clinical subtypes.

Study autism subgroups separately, then compare them

Instead of an a priori assumption that all presentations of ASD represent the same condition, it would be beneficial to study potential autism subgroups separately and merge them only if they are similar for targeted variables. Beyond non-syndromic autism with and without SOD, candidate subgroups include syndromic autism, and validated and non-validated subthreshold individuals. Excluding the aspect of speech from the diagnostic criteria accounts for much heterogeneity and increases the risk of losing the information conveyed by speech to the diagnosis. Having or not a history of SOD has a lifelong impact, not only on language and speech [ 50 ] but also on the nature of peaks of abilities [ 51 ], intelligence subtest profiles [ 52 ], motor difficulties [ 53 ], domains of interest [ 54 ], lateralization of brain structures [ 55 ] and functions [ 56 ], gyrification [ 57 ], white matter [ 58 ], and neural activity during speech-like processing [ 59 ], which are unavoidably blurred when the two subgroups are analyzed together.

Other possible combinations of IQs, co-occurring conditions, and speech levels or histories may also define relevant subgroups, each with its own neurological and genetic correlates and co-existing symptoms. The absence of such precaution results in the dilution of biological or neurocognitive markers, which are only evident in prototypical individuals, representing the center of a category or subcategory. This dilution biases meta-analyses in favor of type 2 errors [ 60 ], closing avenues opened in the first years of autism research [ 61 ]. The assumption that co-variation of specifier values in the target analyses will separate their role in the variables under study is only tenable “everything else being equal”, which is wrong if studies inadvertently collapse differently heterogeneous subgroups, known as Simpson’s paradox [ 62 ].

Research autism before the autism spectrum

Conserving a distinct line of research dedicated to prototypical autism is still justified, whereas it is at risk of disappearing under the current spectrum approach to diagnosis. For example, studying the gradual improvement of socio-communicative signs between preschool and school age in children with an initial prototypical presentation provides information on the temporal characteristics of these signs [ 63 ]. Such knowledge would help improve the specificity of these signs and their contribution to retrospective diagnoses. It is also necessary to preserve a threshold of qualitative similarity with the prototypical autism phenotype, in addition to the non-specific severity threshold.

Re-conceptualize autistic signs/traits

The relationship, either mechanistic or phenotypic, between “autistic traits” and autism, implied by the use of the term “autistic” trait rather than “social” or “repetitive” trait, should be scientifically validated, despite some potentially superficial resemblance. Their “autistic” quality should be ascertained by a) their qualitative aspects, b) their co-occurrence in the prototypical condition, and c) their contextual validation , as the demonstration of a previous, developmentally anterior, above-threshold presentation. Trait studies in the general population or certain non-autistic conditions are not informative about above-threshold autism unless the trait-autism link is validated, revealing the weak overlap between genetic proximity and phenotypic similarity [ 64 ]. Until there is such validation, “autistic traits” are not yet “autistic”. The very notion of “autistic traits”, as in “are there autistic traits in the condition X” may be flawed outside of a context in which their autistic nature is validated .

The widely acknowledged heterogeneity of the autism spectrum is not a biological fact of nature. Neither does it have the force of a scientific fact resulting from empirically and logically sound research. Our current notion of autism is partly a result of our ignorance, reinforced by non-specific criteria and the longing for a consensus. The disappearance of the differential diagnosis of autism as a research question, the unfounded but consensual assimilation of autism and autistic traits, and meta-analyses that condense results contaminated by premature assumptions into apparent truth all promote a lasting mechanism to produce null findings. The time has come to usher research on autism towards prototypical individuals and to limit the heterogeneity of autism to a situation in which the variants of the autism phenotype have a traceable link with prototypical autistic individuals.

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Acknowledgements

We thank Julie Bareil, Stéphanie Caillé, Alexis Beauchamp-Chatel, Daniel Chicouene, Michelle Dawson, Nada Esseily, Melissa Faivre, Baudoin Forgeot d’Arc, David Gagnon, Catie-anne Gagnon, Pascale Grégoire, Guillaume Huguet, Drigissa Ilies, François Lesperance, Sebastien Jacquemont, Edith Ménard, Azalée Mongrain-McNally, Soizic Peignot, Juliette Rabot, and Eya-Mist Rødgaard for the exchanges of ideas that took place during the development of this article.

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Mottron, L., Bzdok, D. Autism spectrum heterogeneity: fact or artifact?. Mol Psychiatry 25 , 3178–3185 (2020). https://doi.org/10.1038/s41380-020-0748-y

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ADHD is one of the most common neurodevelopmental disorders of childhood. It is usually first diagnosed in childhood and often lasts into adulthood. Children with ADHD may have trouble paying attention, controlling impulsive behaviors (may act without thinking about what the result will be), or be overly active.

It is normal for children to have trouble focusing and behaving at one time or another. However, children with ADHD do not just grow out of these behaviors. The symptoms continue, can be severe, and can cause difficulty at school, at home, or with friends.

A child with ADHD might:

daydream a lot
forget or lose things a lot
squirm or fidget
talk too much
make careless mistakes or take unnecessary risks
have a hard time resisting temptation
have trouble taking turns
have difficulty getting along with others

Learn more about signs and symptoms

Get information and support from the National Resource Center on ADHD

There are three different ways ADHD presents itself, depending on which types of symptoms are strongest in the individual:

Predominantly Inattentive Presentation: It is hard for the individual to organize or finish a task, to pay attention to details, or to follow instructions or conversations. The person is easily distracted or forgets details of daily routines.
Predominantly Hyperactive-Impulsive Presentation: The person fidgets and talks a lot. It is hard to sit still for long (e.g., for a meal or while doing homework). Smaller children may run, jump or climb constantly. The individual feels restless and has trouble with impulsivity. Someone who is impulsive may interrupt others a lot, grab things from people, or speak at inappropriate times. It is hard for the person to wait their turn or listen to directions. A person with impulsiveness may have more accidents and injuries than others.
Combined Presentation: Symptoms of the above two types are equally present in the person.

Because symptoms can change over time, the presentation may change over time as well.

Learn about symptoms of ADHD, how ADHD is diagnosed, and treatment recommendations including behavior therapy, medication, and school support.

Causes of ADHD

Scientists are studying cause(s) and risk factors in an effort to find better ways to manage and reduce the chances of a person having ADHD. The cause(s) and risk factors for ADHD are unknown, but current research shows that genetics plays an important role. Recent studies link genetic factors with ADHD. 1

In addition to genetics, scientists are studying other possible causes and risk factors including:

Brain injury
Exposure to environmental risks (e.g., lead) during pregnancy or at a young age
Alcohol and tobacco use during pregnancy
Premature delivery
Low birth weight

Research does not support the popularly held views that ADHD is caused by eating too much sugar, watching too much television, parenting, or social and environmental factors such as poverty or family chaos. Of course, many things, including these, might make symptoms worse, especially in certain people. But the evidence is not strong enough to conclude that they are the main causes of ADHD.

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Deciding if a child has ADHD is a process with several steps. There is no single test to diagnose ADHD, and many other problems, like anxiety, depression, sleep problems, and certain types of learning disabilities, can have similar symptoms. One step of the process involves having a medical exam, including hearing and vision tests , to rule out other problems with symptoms like ADHD. Diagnosing ADHD usually includes a checklist for rating ADHD symptoms and taking a history of the child from parents, teachers, and sometimes, the child.

Learn more about the criteria for diagnosing ADHD

In most cases, ADHD is best treated with a combination of behavior therapy and medication. For preschool-aged children (4-5 years of age) with ADHD, behavior therapy, particularly training for parents, is recommended as the first line of treatment before medication is tried. What works best can depend on the child and family. Good treatment plans will include close monitoring, follow-ups, and making changes, if needed, along the way.

Learn more about treatments

Managing Symptoms: Staying Healthy

Being healthy is important for all children and can be especially important for children with ADHD. In addition to behavioral therapy and medication, having a healthy lifestyle can make it easier for your child to deal with ADHD symptoms. Here are some healthy behaviors that may help:

Developing healthy eating habits such as eating plenty of fruits, vegetables, and whole grains and choosing lean protein sources
Participating in daily physical activity based on age
Limiting the amount of daily screen time from TVs, computers, phones, and other electronics
Getting the recommended amount of sleep each night based on age

If you or your doctor has concerns about ADHD, you can take your child to a specialist such as a child psychologist, child psychiatrist, or developmental pediatrician, or you can contact your local early intervention agency (for children under 3) or public school (for children 3 and older).

The Centers for Disease Control and Prevention (CDC) funds the National Resource Center on ADHD , a program of CHADD – Children and Adults with Attention-Deficit/Hyperactivity Disorder. Their website has links to information for people with ADHD and their families. The National Resource Center operates a call center (1-866-200-8098) with trained staff to answer questions about ADHD.

For more information on services for children with special needs, visit the Center for Parent Information and Resources. To find the Parent Center near you, you can visit this website.

ADHD can last into adulthood. Some adults have ADHD but have never been diagnosed. The symptoms can cause difficulty at work, at home, or with relationships. Symptoms may look different at older ages, for example, hyperactivity may appear as extreme restlessness. Symptoms can become more severe when the demands of adulthood increase. For more information about diagnosis and treatment throughout the lifespan, please visit the websites of the National Resource Center on ADHD and the National Institutes of Mental Health .

National Resource Center on ADHD
National Institute of Mental Health (NIMH)
Faraone, S. V., Banaschewski, T., Coghill, D., Zheng, Y., Biederman, J., Bellgrove, M. A., . . . Wang, Y. (2021). The World Federation of ADHD International Consensus Statement: 208 evidence-based conclusions about the disorder. Neuroscience & Biobehavioral Reviews. doi:10.1016/j.neubiorev.2021.01.022

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