Prevalence and Severity Levels

In The Politics of Autism, I discuss the uncertainty surrounding estimates of autism prevalence. 

Russell, L.A., Tinker, S.C., Shaw, K.A. et al. Prevalence of Autism Spectrum Disorder Severity Levels From the Fifth Edition of the Diagnostic and Statistical Manual (DSM-5) in the Autism and Developmental Disabilities Monitoring Network. J Autism Dev Disord (2026). https://doi.org/10.1007/s10803-026-07292-6    

Abstract

Purpose

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) introduced severity level specifiers for autism spectrum disorder (ASD) with minimal description of the criteria for categorizing three levels of severity (1 to 3, with 3 being the most “severe”). The objective of the analysis was to assess the prevalence of ASD severity levels using population-based surveillance data.

Methods

We analyzed severity level data on children with ASD ages 4- and 8-years-old in 2018 and 2020 in the multisite Autism and Developmental Disabilities Monitoring (ADDM) Network. Prevalence of any documented severity level and of each individual level were calculated overall and by demographic characteristics. Prevalence ratios adjusted for sex, race/ethnicity, age, intellectual disability, ADDM surveillance year, and site (aPRs) and 95% confidence intervals (CIs) were used for comparisons.
Results

Less than half (40.4%) of children with documented ASD diagnoses had any severity level specified in their records, with wide variation by site (4.8%-73.2%). Severity levels were more common in records of children aged 4, in surveillance year 2020, and more often missing in non-Hispanic Black children and from records also missing information on intellectual disability (ID). Higher prevalence of more severe (level 3) ASD was observed among non-Hispanic Black children, children aged 4 years, children in 2020, and children with ID.

Conclusion

Utilization of the DSM-5’s severity levels by community professionals varied widely, limiting their potential utility in identifying needed services and supports for children with ASD.

From the article:

Wide variation in use and assignment of severity levels across sites suggest a lack of standard of practice for determining a child’s level of severity. This may be due to differences in diagnostic training, clinical protocols, or documentation practices. The DSM-5 specifies that “the descriptive severity categories should not be used to determine eligibility for provision of services. Indeed, individuals with relatively better skills overall may experience different or even greater psychosocial challenges. Thus, service needs can only be developed at an individual level and through discussion of personal priorities and targets” (APA, 2013). Providers may therefore question the utility of severity levels defined by support needs, when the DSM also advises that service needs be determined on an individual basis. There is at least one documented instance of severity levels being used to determine eligibility for services: Australia requires at least a level 2 designation to receive their National Disability Insurance Scheme (NDIS) (National Disability Insurance Agency, 2022). It is unknown whether and how often severity levels are used by U.S. service systems.

The degree to which autistic people find utility in the severity levels is unclear. Some who had been diagnosed under the DSM-IV with Asperger’s disorder found the Asperger’s descriptor helpful in understanding themselves and in describing their needs, and they reported concern when it was removed from the DSM-5 (Kapp & Ne’eman, 2020). The severity levels introduced in the DSM-5 could provide a similar type of descriptor that some autistic people find useful. However, other autistic people have expressed concern about the use of severity levels because they might be used to limit care access or to inappropriately group people with very different types of support needs (Kapp & Ne’eman, 2020). Similar concerns have been expressed in other attempts at grouping functioning in ASD, notably with the introduction of the term “profound” ASD, coined by the Lancet Commission on the Future and Care and Clinical Research in Autism (Kapp, 2023; Kripke-Ludwig, 2023; Lord et al., 2022; Pukki et al., 2022).

 

Study: Prevalence Increase May Reflect Improved Identification

In The Politics of Autism, I discuss the uncertainty surrounding estimates of autism prevalence. 

Furnier SM, Gangnon R, Durkin MS. Trends Over Time in the Prevalence of Autism by Adaptive and Intellectual Functioning Levels. Autism Res. 2026 Jan;19(1):e70167. doi: 10.1002/aur.70167. Epub 2025 Dec 28. PMID: 41457676; PMCID: PMC12853238. Abstract:

The autistic community is a large, growing, and heterogeneous population, and there is a need for improved methods to describe their diverse needs. Measures of adaptive functioning collected through public health surveillance may provide valuable information on functioning and support needs at a population level. We aimed to use adaptive behavior and cognitive scores abstracted from health and educational records to describe trends over time in the population prevalence of autism by adaptive level and co- occurrence of intellectual disability (ID). Using data from the Autism and Developmental Disabilities Monitoring Network, years 2000 to 2016, we estimated the prevalence of autism per 1000 8- year- old children by four levels of adaptive challenges (moderate to profound, mild, borderline, or none) and by co- occurrence of ID. The prevalence of autism with mild, borderline, or no significant adaptive challenges increased between 2000 and 2016, from 5.1 per 1000 (95% confidence interval [CI]: 4.6–5.5) to 17.6 (95% CI: 17.1–18.1) while the prevalence of autism with moderate to profound challenges decreased slightly, from 1.5 (95% CI: 1.2–1.7) to 1.2 (95% CI: 1.1–1.4). The prevalence increase was greater for autism without co- occurring ID than for autism with co- occurring ID. The increase in autism prevalence between 2000 and 2016 was confined to autism with milder phenotypes. This trend could indicate improved identification of milder forms of autism over time. It is possible that increased access to therapies that improve intellectual and adaptive functioning of children diagnosed with autism also contributed to the trends

Focus on Helping Autistic People, Not Spreading Pseudoscience

 A number of posts have discussed Trump's support for discredited notions about autism 

Challenging Claims of an Autism Epidemic — Misconceptions and a Path Forward

Authors: Tara Eicher, Ph.D., John Quackenbush, Ph.D., and Ari Ne’eman, Ph.D.Published January 17, 2026DOI: 10.1056/NEJMp2514250

The history of autism offers many reasons for fraught relationships between clinicians and autistic persons and their families. For decades, the psychiatric and especially psychoanalytic communities relied on psychodynamic theories of the causation of autism that blamed “refrigerator mothers.” It is thus unsurprising that a culture of distrust exists between parents of autistic children and physicians — a distrust that the president only exacerbates when he suggests that physicians are withholding information from families about environmental causes. This rhetoric, specifically the blaming of mothers who use acetaminophen during pregnancy for their children’s impairments, harkens back to past decades. Such rhetoric can cause concrete harms, encouraging expectant mothers to forgo essential treatment for fever and leading parents to turn to an exploitative alternative medicine industry peddling costly pseudoscience that frequently harms autistic people.

Autistic people and their families do deserve answers — not answers involving ill-conceived “causes” and pseudoscientific “cures,” but answers to their aspirations for improved services, medical care, and inclusion in society. Much needs to be done to shift the focus of existing autism-research investments toward issues of immediate relevance to autistic people and their families. Researchers who make this shift can help address the root causes of mistrust that make some parents of autistic people so receptive to pseudoscientific treatments and theories of causation. Unfortunately, the direction the federal government is taking on autism seems calculated to exacerbate the divide.

Research programs can be designed to maximize the benefits for autistic people and their families by studying both causes and the most effective and meaningful services and supports in an appropriate balance. Such a constructive shift will not be accomplished, however, by means of alarmist claims about autism as an epidemic, chasing of ill-supported and debunked theories of causation, and further stigmatizing autism. Instead, it will require building strong, collaborative research programs in which researchers from diverse fields join forces with autistic people and their families to generate lasting change.

The DSM and Prevalence

In The Politics of Autism, I discuss the uncertainty surrounding estimates of autism prevalence. 

 Dr. Allen Frances, the lead editor of previous version of the manual, says that the diagnostic instructions are confusing, so the diagnosis will vary from rater to rater and place to place. “It will be even more impossible than it is now to determine rates of autism and why they shift so much over time.”   A more recent study says that prevalence estimates are likely to decline under DSM-5 – but it cautions that policies for service eligibility and diagnostic tools will change in response to the revised criteria. Clinicians may react by looking for more symptoms to back up ASD diagnoses.

And DSM-5 is not the last word.  Whereas the titles of previous editions included Roman numerals (DSM-III, DSM-IV), the new one instead has an Arabic numeral to make it easier to designate revisions. The future will bring DSM-5.1, DSM-5.2, and so on, which may include further changes in the way we describe and diagnose autism.

 Allen Frances at NYT:

The rapid rise in autism cases is not because of vaccines or environmental toxins, but rather is the result of changes in the way that autism is defined and assessed — changes that I helped put into place.

In the late 1980s and early 1990s, I chaired the task force charged with creating the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders, or the D.S.M.-IV. Sometimes called the “bible of psychiatry,” the D.S.M. influences medical practice, insurance coverage, education and treatment selection.

In the third edition of the D.S.M., published in 1980, autism was tightly defined and considered extremely rare. Criteria for the diagnosis required a very early onset (before age 3) of severe cognitive, interpersonal, emotional and behavioral problems.

But my task force approved the inclusion of the new diagnosis, Asperger’s disorder, which is much milder in severity than classic autism and much more common. In doing so, we were responding to child psychiatrists’ and pediatricians’ concerns for children who did not meet the extremely stringent criteria for classic autism, but had similar symptoms in milder form and might benefit from services.

Based on careful studies, our task force predicted that the addition of Asperger’s disorder would modestly increase the rate of children given an autism-related diagnosis. Instead, the rate increased more than 16-fold, to one in 150 from an estimated one in 2,500 in the span of a decade. It has been climbing more gradually ever since and is one in 31 today. Our intentions were good, but we underestimated the enormous unintended consequences of adding the new diagnosis.

The resulting explosion in cases included many instances of overdiagnosis — children were labeled with a serious condition for challenges that would better be viewed as a variation of normal. It also sowed the seeds of conspiracy theories and anti-vaccine beliefs as people wondered how to explain the rising cases.

Many large studies have come to the same conclusion: Vaccines don’t cause autism. The role, if any, of environmental toxins is still to be determined, but there is no known environmental factor that can explain the sudden jump in diagnoses. The changes we made to the diagnosis in the D.S.M.-IV can.

Why did autism-related diagnoses explode so far beyond what our task force had predicted? Two reasons. First, many school systems provide much more intensive services to children with the diagnosis of autism. While these services are extremely important for many children, whenever having a diagnosis carries a benefit, it will be overused. Second, overdiagnosis can happen whenever there’s a blurry line between normal behavior and disorder, or when symptoms overlap with other conditions. Classic severe autism had so tight a definition it was hard to confuse it with anything else; Asperger’s was easily confused with other mental disorders or with normal social avoidance and eccentricity. (We also, regrettably, named the condition after Hans Asperger, one of the first people to describe it, not realizing until later that he had collaborated with the Nazis.)

Adult Autism Prevalence

In The Politics of Autism, I discuss the uncertainty surrounding estimates of autism prevalence.

Nidhi Subbaraman at WSJ:

Overall, the rate of autism in people 18 or older more than doubled between 2011 and 2019, from 4.2 per 1,000 to 9.5 per 1,000, according to an analysis of Medicaid data published in the journal JAMA Psychiatry in 2023.

Researchers saw the most rapid growth in adults between the ages of 26 and 34, according to a study, published in the journal JAMA Network Open in 2024, that analyzed U.S. health records and insurance claims for more than nine million individuals a year from 2011 to 2022. That group’s rate of autism increased from 0.7 per 1,000 people in 2011 to 3.7 per 1,000 in 2022.

Some of this growth comes from autistic children aging into adulthood.

For adults seeking evaluations for the first time, scientists attribute the rise to a variety of factors.

Social media has increased awareness of autism. Autism has shed the stigma it used to hold. The definition of the condition has expanded over time to include a broader range of behaviors. And some parents who have children diagnosed with autism then recognize their own challenges and seek out evaluations, said Michelle Gorenstein-Holtzman, a clinical psychologist who works with adults at the NewYork-Presbyterian/Weill Cornell Medical Center and the Center for Autism and the Developing Brain.

Three years ago, before she joined, the center did one adult autism evaluation a month. Now Gorenstein-Holtzman does two a week.

Causation and Prevalence

In The Politics of Autism, I discuss the uncertainty surrounding estimates of autism prevalence.

Leana S. Wen at WP:

Outside of specific genetic diseases, scientists have identified more than 250 genes that are associated with a higher likelihood of ASD. As Maureen Durkin, a professor at the University of Wisconsin-Madison, explained to me, some of these genes are also associated with beneficial traits. “It’s not as simple as ‘these are causes of autism, and you’d want to edit them out of the genome,’” she said.

...

Data from around the world support expanded diagnosis as the key factor behind climbing autism rates. A study in Denmark, published in JAMA, attributed 60 percent of ASD’s increase to broadened criteria and better reporting. A study in Canada concluded that 33 percent of the increase was due to diagnoses switching from another condition. Fombonne noted that similar trends are seen in every country. “The fact that it happened everywhere at the same time is not suggestive of something happening in the environment,” he said.

The CDC’s reports support the expanded diagnosis theory as well. Before 2016, the highest ASD prevalence was among White children and kids from areas of higher socioeconomic status. As screening improved, disparities decreased; in 2020, higher prevalence was seen in Black and Hispanic children and the association with household income faded.

...

Are there any potential biological reasons for increasing autism rates? The experts I spoke to have differing views. Laurent Mottron, a University of Montreal psychiatrist and researcher, believes the number of people profoundly impacted by autism — what he calls “prototypical autism” — has not increased. Others, like Mandell and Durkin, said it’s possible that factors such as advancing parental age and better medical care that improves survival rates for premature infants could be contributing to the increase.

CDC Gets Prevalence Right, for Now

In The Politics of Autism, I discuss the uncertainty surrounding estimates of autism prevalence

Azeen Ghorayshi at NYT:

The percentage of American children estimated to have autism spectrum disorder increased in 2022, continuing a long-running trend, according to data released on Tuesday by the Centers for Disease Control and Prevention.

Among 8-year-olds, one in 31 were found to have autism in 2022, compared with 1 in 36 in 2020. That rate is nearly five times as high as the figure in 2000, when the agency first began collecting data.

The health agency noted that the increase was most likely being driven by better awareness and screening, not necessarily because autism itself was becoming more common.

That diverged sharply from the rhetoric of the nation’s health secretary, Robert F. Kennedy Jr., who on Tuesday said, “The autism epidemic is running rampant.”

The conclusion of the report:

Autism prevalence among children aged 8 years increased from 2020 to 2022. Prevalence in 2022 continued to vary widely across sites. Differences in prevalence over time and across sites can reflect differing practices in ASD evaluation and identification and availability and requirements that affect accessibility of services (e.g., meeting financial or diagnostic eligibility requirements). A/PI, Black, Hispanic, and multiracial children continued to have higher prevalence of ASD than White children, and children in low MHI or high vulnerability communities for five sites had higher prevalence of ASD than children in high MHI or low vulnerability communities. As evidence grows of increased access to identification among previously underserved groups, attention might shift to what factors, such as SDOH [social determinants of health], could lead to higher rates of disability among certain populations. A higher rate of ASD identification by 48 months was found among children born in 2018 compared with children born in 2014. The cohort born in 2018 received more evaluations and ASD identifications than the cohort born in 2014 did during the same age window; disruption was visible at COVID-19 pandemic onset in early 2020 but the pattern of higher identification reappeared by the end of 2020. Continued increases in prevalence and improvements in early identification of ASD could indicate increasing need for services. Opportunities exist to learn from successful policies, systems, and practices in different communities and implement approaches for equitable identification or service eligibility to help families or persons receive the support they need as early as possible to improve outcomes for children with ASD.

Trump Asks RFK Jr. to Investigate Autism

In The Politics of Autism, I analyze the myth that vaccines cause autism. This bogus idea can hurt people by allowing diseases to spread.    Examples include measles, COVID, flu, and polio.

A number of posts discussed Trump's support for the discredited notion.

 Another leading anti-vaxxer is presidential candidate Robert F. Kennedy, Jr.  He has repeatedly compared vaccine mandates to the Holocaust.  Rolling Stone and Salon retracted an RFK article linking vaccines to autism.  He is part of the "Disinformation Dozen." He helped cause a deadly 2019 measles outbreak in Samoa.

He is now Trump's secretary of HHS.

Trump mentioned autism in his rambling speech to Congress last night.  

 [Not] long ago, and you can’t even believe these numbers, one in 10,000 children have autism. One in 10,000. And now it’s one in 36. There’s something wrong. One in 36. Think of that. So we’re going to find out what it is and there’s nobody better than Bobby and all of the people that are working with you. You have the best to figure out what is going on. OK, Bobby, good luck. It’s a very important job. Thank you. Thank you.

Adam Edelman and Jane C. Timm at NBC:

According to the Centers for Disease Control and Prevention, this ratio is correct. But the statistic is often used to justify opposition to vaccination.

Health and Human Services Secretary Robert F. Kennedy Jr. has pointed to vaccines to explain the substantial rise in autism diagnoses in recent decades, which have ballooned from an estimated 1 in 150 children in 2000 to 1 in 36 today.

But the science is clear that vaccines don’t cause autism.

Rather, research suggests that much of the increase is due to increasing awareness and screening for the condition, changing definitions of autism to include milder conditions on the spectrum that weren’t recognized in previous years and advances in diagnostic technology.

Finding the causes of autism is complicated, because it’s not a single disorder, scientists and experts have told NBC News. In addition, those scientists and experts have said they believe that people develop autistic traits because of a combination of genetic vulnerability and environmental exposures.

Teddy Rosenbluth at NYT:

As a measles outbreak expands in West Texas, Robert F. Kennedy Jr., the health and human services secretary, on Tuesday cheered several unconventional treatments, including cod liver oil, but again did not urge Americans to get vaccinated.

In a prerecorded interview that aired on Fox News, Mr. Kennedy said that the federal government was shipping doses of vitamin A to Gaines County, the epicenter of the outbreak, and helping to arrange ambulance rides.

H.H.S. officials previously said they were shipping doses of the measles-mumps-rubella vaccine to Texas, but Mr. Kennedy did not discuss vaccination.

Texas doctors had seen “very, very good results,” Mr. Kennedy claimed, by treating measles cases with a steroid, budesonide; an antibiotic called clarithromycin; and cod liver oil, which he said had high levels of vitamin A and vitamin D.

While physicians sometimes administer doses of vitamin A to treat children with severe measles cases, cod liver oil is “by no means” an evidence-based treatment, said Dr. Sean O’Leary, chair of the American Academy of Pediatrics Committee on Infectious Diseases.

Dr. O’Leary added that he had never heard of a physician using the supplement against measles.

Study: 61.8m Autistic People in the World

In The Politics of Autism, I discuss the uncertainty surrounding estimates of autism prevalence. c

 Elana Gotkine at MedicalXpress:

Damian Santomauro, Ph.D., from the University of Queensland in Archerfield, Australia, and colleagues conducted a systematic literature review to estimate the global prevalence and health burden of autism spectrum disorder.

The researchers found that in 2021, an estimated 61.8 million individuals were on the autism spectrum globally. The global age-standardized prevalence was 788.3 per 100,000 people, which was equivalent to 1,064.7 and 508.1 males and females with autism per 100,000 males and females, respectively.

Globally, autism spectrum disorder accounted for 11.5 million disability-adjusted life-years (DALYs), which was equivalent to 147.6 DALYs per 100,000 people. Age-standardized DALY rates varied from 126.5 to 204.1 per 100,000 people in Southeast Asia, East Asia, and Oceania and in the high-income super region, respectively. Across the lifespan, DALYs were evident, emerging for children younger than 5 years (169.2 DALYs per 100,000 people) and decreasing with age (163.4 and 137.7 DALYs per 100,00 people aged younger than 20 and aged 20 years or older, respectively). For people younger than 20 years, autism spectrum disorder was ranked within the top 10 causes of nonfatal health burden.

From: Damian F Santomauro et al, The global epidemiology and health burden of the autism spectrum: findings from the Global Burden of Disease Study 2021, The Lancet Psychiatry (2024). DOI: 10.1016/S2215-0366(24)00363-8

Prevalence did not vary substantially over time. Studies reporting an increase in the prevalence of the autism spectrum have often relied on registries or administrative records to determine prevalence. Studies using random sampling or consistent active-case finding did not show this trend. This finding aligns with previous work suggesting autistic characteristics in the population have remained stable over time despite a rise in registered diagnoses.32 Nonetheless, the absence of temporal trends in our analysis should be interpreted with caution as we relied on a 15-year time window (reduced from 25 years) to model prevalence data. This time window might have limited our ability to explore temporal trends, but a further reduction was not possible because of data sparsity.

Autism spectrum disorder ranked within the top-ten causes of non-fatal health burden for young people (age <20 years), emphasising the need for early detection and developmental support for autistic people.3,4,33 Most epidemiological investigations into the autism spectrum have been predominantly centred on children and adolescents, leaving a gap in our understanding of the autism spectrum in adults. The prevalence and health burden of autism spectrum disorder persisted across the lifespan, beginning to decline from age 60 years. DisMod MR 2.1 estimated prevalence while also taking into consideration data available from other epidemiological parameters. In this case, with most of our raw prevalence data limited to younger cohorts, the age pattern in prevalence was informed by excess mortality data modelled by DisMod-MR 2.1 because of limited available prevalence data in adulthood. Because of limited data availability, all mortality data sourced from the systematic review relied on passive case finding (eg, from administrative records). This method might overestimate excess mortality for all autistic people, leading to an underestimation of prevalence in adulthood.

32. Lundström, S ∙ Reichenberg, A ∙ Anckarsäter, H ∙ et al.
Autism phenotype versus registered diagnosis in Swedish children: prevalence trends over 10 years in general population samplesBMJ. 2015; 350, h1961 Crossref Scopus (126)  PubMed Google Scholar
33. Peters-Scheffer, N ∙ Didden, R ∙ Korzilius, H ∙ et al. A meta-analytic study on the effectiveness of comprehensive ABA-based early intervention programs for children with autism spectrum disordersRes Autism Spect Disorder. 2011; 5:60-6  Crossref Scopus (0) Google Scholar 

 

Finding More Autism Among Adults

In The Politics of Autism, I discuss the uncertainty surrounding estimates of autism prevalence. 

Until recently, there was very little research into prevalence among adults.

And getting a diagnosis as an adult is difficult.

Grosvenor LP, Croen LA, Lynch FL, et al. Autism Diagnosis Among US Children and Adults, 2011-2022. JAMA Netw Open. 2024;7(10):e2442218. doi:10.1001/jamanetworkopen.2024.42218

Question How have autism diagnosis rates changed over time among children and adults seeking care from a network of health systems in the US?

Findings In this cross-sectional study of electronic US health and insurance claims records for over 9 million individuals per year from 2011 to 2022, relative increases in autism diagnosis rates were greatest among young adults compared with all other age groups, female compared with male individuals, and some racial and ethnic minority groups compared with White individuals among children but not adults.

Meaning Patterns of increase in autism diagnosis rates reflect a need for expanded health care services and continued research on sociodemographic disparities among this growing population.

Abstract

Importance An improved understanding of autism spectrum disorder (ASD) prevalence over time and across the lifespan can inform health care service delivery for the growing population of autistic children and adults.

Objective To describe trends in the prevalence of ASD diagnoses using electronic records data from a large network of health systems in the US.

Design, Setting, and Participants This cross-sectional study examined annual diagnosis rates in health records of patients in US health systems from January 1, 2011, to December 31, 2022. Eligible individuals were included in the study sample for a given calendar year if they were enrolled in a participating health system for at least 10 months out of the year. Data were extracted from 12 sites participating in the Mental Health Research Network, a consortium of research centers embedded within large, diverse health care systems.

Main Outcome and Measures Diagnoses of ASD were ascertained using International Classification of Diseases, Ninth Revision (ICD-9) and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) revision codes. Annual diagnosis rates were calculated as the number of unique members diagnosed, divided by the total members enrolled.

Results A total of 12 264 003 members were enrolled in 2022 (2 359 359 children aged 0 to 17 years [19.2%]; 6 400 222 female [52.2%]; 93 002 American Indian or Alaska Native [0.8%], 1 711 950 Asian [14.0%], 952 287 Black or African American [7.8%], 2 971 355 Hispanic [24.2%], 166 144 Native Hawaiian or Pacific Islander [1.4%], and 6 462 298 White [52.7%]). The ASD diagnosis rate was greatest among 5-to-8-year-olds throughout the study period and increased by 175% among the full sample, from 2.3 per 1000 in 2011 to 6.3 per 1000 in 2022. The greatest relative increase in diagnosis rate from 2011 to 2022 occurred among 26-to-34-year-olds (450%) and increases were greater for female vs male individuals among children (305% [estimated annual percentage change (EAPC), 13.62 percentage points; 95% CI, 12.49-14.75 percentage points] vs 185% [EAPC, 9.63 percentage points; 95% CI, 8.54-10.72 percentage points], respectively) and adults (315% [EAPC, 13.73 percentage points; 95% CI, 12.61-14.86 percentage points] vs 215% [EAPC, 10.33 percentage points; 95% CI, 9.24-11.43 percentage points]). Relative increases were greater in racial and ethnic minority groups compared with White individuals among children, but not adults.

Conclusions and Relevance In this cross-sectional study of children and adults in the US, ASD diagnosis rates increased substantially between 2011 and 2022, particularly among young adults, female children and adults, and children from some racial or ethnic minority groups. Diagnosis prevalence trends generated using health system data can inform the allocation of resources to meet the service needs of this growing, medically complex population.

Autism and COVID

In The Politics of Autism, I discuss evaluation, diagnosis, and the uncertainty of prevalence estimates.

From the Columbia University Irving Medical Center:

Children born during the first year of the pandemic, including those exposed to COVID in utero, were no more likely to screen positive for autism than unexposed or pre-pandemic children, found researchers from Columbia University Vagelos College of Physicians and Surgeons.


The study(link is external and opens in a new window), published in JAMA Network Open, is the first report on autism risk among pandemic-era children.

“Autism risk is known to increase with virtually any kind of insult to mom during pregnancy, including infection and stress,” says Dani Dumitriu, associate professor of pediatrics and psychiatry and senior author of the study. “The scale of the COVID pandemic had pediatricians, researchers, and developmental scientists worried that we would see an uptick in autism rates. But reassuringly, we didn’t find any indication of such an increase in our study.”

It’s important to note, Dumitriu adds, that the study did not look at autism diagnosis, only the risk of developing autism as measured by a screening questionnaire filled in by the child’s parents. “It’s too early to have definitive diagnostic numbers,” she says. “But this screener is predictive, and it’s not showing that prenatal exposure to COVID or the pandemic increases the likelihood of autism.

“There has been broad speculation about how the COVID generation is developing, and this study gives us the first glimmer of an answer with respect to autism risk.”
Investigating autism risk and COVID

Dumitriu’s team has been studying the potential effects of pandemic-related maternal stress and maternal infection on child neurodevelopment at different points since birth through the COMBO (COVID-19 Mother Baby Outcomes) Initiative. Children who were in the womb during the first phases of the pandemic are now reaching the age when early indicators of autism risk could emerge.

The current study examined nearly 2,000 children born at NewYork-Presbyterian’s Morgan Stanley Children’s Hospital and Allen Hospital between January 2018 and September 2021. Autism risk was calculated based on responses from a neurodevelopment screening questionnaire that pediatricians give to parents to evaluate toddlers’ behavior. Scores were compared for children born during and prior to the pandemic and for children with and without in utero exposure to COVID. All children were screened between 16 and 30 months of age.

Reassuring results

The researchers found no difference in positive autism screenings between children born before the pandemic and those born during the pandemic.

“COVID is still quite prevalent, so this is comforting news for pregnant individuals who are worried about getting sick and the potential impact on autism risk,” Dumitriu says.

Surprisingly, the study also found that fewer children exposed to COVID in utero screened positive for autism compared with children whose moms did not have COVID.

“We suspect that having COVID during pregnancy may have influenced parents’ assessment of their child’s behaviors,” Dumitriu says. “Parents who did not have COVID may have experienced higher stress—due to the constant worry of getting sick and the vigilance around preventing infection—and may have been more likely to report concerning child behaviors.”

Could autism show up later in childhood?

As the children age, the researchers will continue to monitor them for autism diagnoses. But based on the current results, Dumitriu thinks it unlikely that an uptick in autism related to COVID will occur.

“Children who were in the womb early in the pandemic are now reaching the age when early indicators of autism would emerge, and we’re not seeing them in this study,” Dumitriu says. “And because it’s well-known that autism is influenced by the prenatal environment, this is highly reassuring.”

But other impairments may emerge later, and the researchers will continue to study the children’s neurodevelopment as they age.

Several studies of infants who were in utero during previous pandemics, natural disasters, famines, and wartime have shown that other neurodevelopmental conditions, potentially triggered by the stressful environment, can emerge in adolescence and even early adulthood.

“We need to acknowledge the unique experience and environment of children who were born during the pandemic—including parental stress and social isolation—and continue to monitor them for potential developmental or psychiatric differences,” says Morgan Firestein, associate research scientist in psychiatry and first author of the study.

Topics
Infectious Diseases, COVID-19, Pediatrics, Research

References

More information

Dani Dumitriu, MD, is also an attending pediatrician in the Newborn Medicine Section at NewYork-Presbyterian's Morgan Stanley Children’s Hospital.

The study, titled "Positive Autism Screening Rates in Toddlers Born During the Covid-19 Pandemic(link is external and opens in a new window),” was published online Sept. 23, 2024, in JAMA Network Open.
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Estimate of ASD Prevalence

In The Politics of Autism, I discuss the uncertainty surrounding estimates of autism prevalence.

BRIEF RESEARCH REPORT article
Front. Psychiatry
Sec. Autism
Volume 15 - 2024 | doi: 10.3389/fpsyt.2024.1471969

Prevalence and trends of autism spectrum disorder and other developmental disabilities among children and adolescents in the United States from 2019 to 2021 Provisionally accepted

 Wen-Rong Ge Cancan Zhang Guang Yang Bo Zhang 

The National Health Interview Survey (NHIS) is a comprehensive health survey conducted by the National Center for Health Statistics (NCHS) in the U.S., providing valuable insights into the health status of the population. This study focuses on the NHIS child survey between 2019 and 2021, exploring developmental disabilities in U.S. children, including autism spectrum disorder (ASD), attention deficit/hyperactivity disorder or attention-deficit disorder (ADHD/ADD), intellectual disability (ID), other developmental delay (other DD), and learning disability (LD).Objective: Leveraging NHIS data, our primary objective is to investigate the latest trends and disparities in the prevalence of developmental disabilities among various racial-ethnic groups.Methods: Employing a repeated cross-sectional design, we analyzed NHIS data from 2019 to 2021, focusing on children aged 3-17. The survey employed a meticulous stratified multi-stage sampling design. We utilized SAS version 9.4 for data analysis, calculating race-ethnicity-specific prevalence rates and employing weighted linear regression and the Rao-Scott chi-square test for trend analysis.Results: Among 19,490 children, prevalence rates varied: ASD (3.11%), ADHD/ADD (9.50%), ID (1.85%), other DD (5.66%), and LD (7.49%). Non-Hispanic black children exhibited higher rates of ID and LD, while non-Hispanic white children had the highest ADHD/ADD prevalence. Disparities persisted across sociodemographic subgroups, with variations in prevalence rates.Our study reveals an increase in ASD prevalence and persistent disparities among racial-ethnic groups.Non-Hispanic black children face elevated risks of ID and LD, while non-Hispanic white children exhibit higher rates of ADHD/ADD.

IDEA Data 2022-23

In The Politics of Autism, I write about special education and the Individuals with Disabilities Education Act. 

From the National Center for Education Statistics:

Children 3 to 21 years old with an autism designation served under the Individuals with Disabilities Education Act (IDEA), Part B

..........................................................2012-13        2022-23

Number served in thousands................498..............980

Percent of children served................... 7.8..............13.0

Percent of total enrollment...................1.0................2.0

California Data

In The Politics of Autism, I discuss evaluation and diagnosis.

O’Sharkey, K., Mitra, S., Paik, Sa. et al. Trends in the Prevalence of Autism Spectrum Disorder in California: Disparities by Sociodemographic Factors and Region Between 1990–2018. J Autism Dev Disord (2024). https://doi.org/10.1007/s10803-024-06371-w

Abstract

Autism Spectrum Disorders (ASD) prevalence has risen globally, with regional variation and sociodemographic disparities affecting diagnosis and intervention. This study examines ASD trends from 1990 to 2018 in California (CA), focusing on sociodemographic factors that may inform policy/interventions. Using CA Department of Public Health birth records (1990–2018) and Developmental Services ASD cases (1994–2022), we analyzed diagnosis incidence by age 4 or 8, stratified by sociodemographic and regional factors. From 1990 to 2018, for each birth year the cumulative incidence of ASD by 4 and 8 years of age in CA increased while the diagnosis age decreased. Distinct patterns emerged over these three decades. Children born to White and Asian and Pacific Islander (API) mothers, or to mothers with higher education or living in high socioeconomic status (SES) neighborhoods exhibited higher ASD cumulative incidences throughout the 1990s and early 2000s. However, in the mid-2000s, ASD incidence in children born to Black or Hispanic mothers, with low education, or living in low SES neighborhoods surpassed that of White/API children or those living in high SES neighborhoods. Black or Hispanic children now have the highest ASD cumulative incidence, even though age at first diagnosis remains lowest in high SES regions, for the highly educated, and for White/API children. ASD cumulative incidence in CA from 1990 to 2018 exhibited demographic reversals with higher rates in children born to Black or Hispanic mothers or lower SES neighborhoods. Black and Hispanic children still have delayed age at diagnosis compared to White/API children.

Census Halts Question Change

In The Politics of Autism, I discuss evaluation, diagnosis, and the uncertainty of prevalence estimates.

Hansi Lo Wang at NPR:

The U.S. Census Bureau is no longer moving forward with a controversial proposal that could have shrunk a key estimated rate of disability in the United States by about 40%, the bureau's director said Tuesday in a blog post.

The announcement comes just over two weeks after the bureau said the majority of the more than 12,000 public comments it received about proposed changes to its annual American Community Survey cited concerns over changing the survey's disability questions.

...

The American Community Survey currently asks participants yes-or-no questions about whether they have "serious difficulty" with hearing, seeing, concentrating, walking and other functional abilities.

To align with international standards and produce more detailed data about people's disabilities, the bureau had proposed a new set of questions that would have asked people to rate their level of difficulty with certain activities.

Based on those responses, the bureau was proposing that its main estimates of disability would count only the people who report "A lot of difficulty" or "Cannot do at all," leaving out those who respond with "Some difficulty." That change, the bureau's testing found, could have lowered the estimated share of the U.S. population with any disability by around 40% — from 13.9% of the country to 8.1%.

Prevalence in Israel

In The Politics of Autism, I note that we need more study of how autistic people fare in other countries.

Dinstein, I., Solomon, S., Zats, M., Shusel, R., Lottner, R., Gershon, B. B., Meiri, G., Menashe, I., & Shmueli, D. (2024). Large increase in ASD prevalence in Israel between 2017 and 2021. Autism Research, 1–9. https://doi.org/10.1002/aur.3085

Abstract:

Accurate estimation of annual changes in autism spectrum disorders (ASD) prevalence is critical for planning the expansion of diagnostic, education, and intervention services at an adequate rate. Previous studies from Israel have reported that ASD prevalence among 8-year-old children has increased from estimates of 0.3% in 2008 to 0.65% in 2015 and 1.3% in 2018. Here, we analyzed data acquired from the National Insurance Institute of Israeli (NII), a governmental organization that approves and monitors all ASD children who receive welfare services in Israel, and Clalit Health Services (CHS), the largest Health Maintenance Organization in Israel that provides health services to ~52% of the population. Data from both sources included annual data files from 2017 to 2021 containing the number of ASD cases per year of birth for 1–17-year-old children. This allowed us to estimate annual ASD prevalence among 3.5 million children born between 2000 and 2020 in Israel. Both data sources revealed a nearly two-fold increase in ASD prevalence among 1–17-year-old children from 2017 to 2021. Estimated prevalence rates differed across age groups with 2–3-year-old (day-care) children increasing from 0.27% to 1.19% (>4 fold change), 4–6-year-old (pre-school) children increasing from 0.8% to 1.83%, and 8-year-old children increasing from 0.82% to 1.56% in NII data. These results demonstrate that autism prevalence continues to increase in Israel with a shift towards diagnosis at earlier ages. These findings highlight the challenge facing health and education service providers in meeting the needs of a rapidly growing autism population.

Prevalence in Australia

In The Politics of Autism, I discuss international perspectives. I also discuss evaluation, diagnosis, and the uncertainty of prevalence estimates.

Maathu Ranjan and Dr Anthony Lowe, "Providing Better Support for Children with Autism and Developmental Delay," Actuaries Institute, September 2023."

Over the past ten years, the National Disability Insurance Scheme (NDIS) has transformed the lives of hundreds of thousands of Australians living with disability — there is much to be proud of. However, the reality of the current Scheme is very different to the original vision. In large part, this is because the Scheme was envisioned and legislated based on the social model of disability but has been implemented using the medical model. One of the fastest-growing cohorts of participants is children, particularly children with autism and developmental delay. The system gives families little choice but to seek out formal medical diagnoses, resulting in considerable diagnostic waitlists and the prevention of timely access to early interventions, which evidence shows are most effective. We should use this current window of opportunity presented by the Independent Review of the NDIS to implement a social model of disability which would better support children and help make the NDIS financially sustainable by restoring specialist support in everyday settings and ensuring the support it provides is delivered in the most effective way. 

The Financial Review reproduces a graph from Ranjan's new paper.  See the LinkedIn post.

Prevalence and Underdiagnosis in NY-NJ Metro

In The Politics of Autism, I discuss evaluation, diagnosis, and the uncertainty of prevalence estimates.

Walter Zahorodny and colleagues have an article at the Journal of Autism and Developmental Disorders: "Prevalence and Characteristics of Adolescents with Autism Spectrum Disorder in the New York-New Jersey Metropolitan AreaBrief Reportith Autism Spectrum Disorder in the New York-New Jersey Metropolitan Area."

Abstract

Purpose

Almost all epidemiologic studies estimating autism spectrum disorder (ASD) prevalence have focused on school-age children. This study provides the first population-based data on the prevalence and expression of ASD among adolescents in a large US metropolitan region.

Methods

Active multiple source ASD surveillance of adolescents aged 16-years was conducted according to the Autism and Developmental Disabilities Monitoring (ADDM) Network method in a four-county New Jersey metropolitan region. Prevalence estimates are provided, characteristics are described and comparison of the distribution and characteristics of ASD is offered for this cohort, at 8 and 16-years.

Results

ASD prevalence was 17.7 per 1000 (95% CI: 16.3–19.2)]. One-in-55 males and one in 172 females were identified with ASD. High-SES was positively associated with ASD and White adolescents had higher ASD prevalence (22.2 per 1000) than Hispanic adolescents (13.1 per 1000). One in four study-confirmed individuals with ASD did not have an ASD diagnosis. A majority of ASD adolescents (58.8%) had a co-occurring neuropsychiatric disorder. White and High-SES individuals had greater likelihood of co-occurring disorder. The demographic distribution and functional profile of ASD was similar in this cohort at 8 and 16-years.

Conclusion

Approximately one-in-55 adolescents in our area had ASD, in 2014, and one-in-4 16-year-olds with ASD was not diagnosed. A majority (3-in-5) of the adolescents with ASD had a co-occurring neuropsychiatric disorder. ASD under-identification and the high frequency of co-disorders in adolescents with ASD pose significant challenges to care and support.

Prevalence in England

In The Politics of Autism, I discuss evaluation, diagnosis, and the uncertainty of prevalence estimates.

Elizabeth O'Nions and colleagues have an article in Lancet Regional Health Europe titled "Autism in England: assessing underdiagnosis in a population-based cohort study of prospectively collected primary care data."

Summary

Background

Autism has long been viewed as a paediatric condition, meaning that many autistic adults missed out on a diagnosis as children when autism was little known. We estimated numbers of diagnosed and undiagnosed autistic people in England, and examined how diagnostic rates differed by socio-demographic factors.

Methods

This population-based cohort study of prospectively collected primary care data from IQVIA Medical Research Data (IMRD) compared the prevalence of diagnosed autism to community prevalence to estimate underdiagnosis. 602,433 individuals registered at an English primary care practice in 2018 and 5,586,100 individuals registered between 2000 and 2018 were included.

Findings

Rates of diagnosed autism in children/young people were much higher than in adults/older adults. As of 2018, 2.94% of 10- to 14-year-olds had a diagnosis (1 in 34), vs. 0.02% aged 70+ (1 in 6000). Exploratory projections based on these data suggest that, as of 2018, 463,500 people (0.82% of the English population) may have been diagnosed autistic, and between 435,700 and 1,197,300 may be autistic and undiagnosed (59–72% of autistic people, 0.77%–2.12% of the English population). Age-related inequalities were also evident in new diagnoses (incidence): c.1 in 250 5- to 9-year-olds had a newly-recorded autism diagnosis in 2018, vs. c.1 in 4000 20- to 49-year-olds, and c.1 in 18,000 people aged 50+.

Interpretation

Substantial age-related differences in the proportions of people diagnosed suggest an urgent need to improve access to adult autism diagnostic services.

 Evidence before this study

We searched PubMed from database inception to October 17th, 2022 using the search terms: (1) ‘autism’, and (2) ‘incidence’ or ‘prevalence’ or ‘underdiagnosis’ or ‘under-diagnosis’, without language restrictions. This identified articles describing the global incidence and prevalence of autism. Some studies identified rates of diagnosed autism, and others used active sampling approaches (community case-finding) to identify the numbers of autistic individuals both diagnosed and undiagnosed in a population. The vast majority of studies focused on rates of autism in children. There was a high degree of variability in estimated autism prevalence by year, by region, and by method of case ascertainment. Most studies investigating time-trends reported increasing rates of diagnosed autism over the past 20 years. No studies estimated the extent to which autism was underdiagnosed at a national level or inequalities in diagnosis by comparing diagnosed autism prevalence for a nationally-representative population of children and adults with estimates of true autism prevalence.

Added value of this study

This study is the first to estimate underdiagnosis of autism using data from English primary care for more than 5 million individuals, a critical question given the key role of diagnosis in providing health and social services to autistic people. We are the first to provide upper and lower bound projected estimates of autism underdiagnosis in England, and to establish how these vary according to key demographic and clinical indices. Applying estimates of true prevalence derived from community case-finding studies and the highest rate of diagnosed autism in any age-band in this dataset, we found evidence suggesting high levels of underdiagnosis, particularly in older age groups. We estimate that between 150,000 and 500,000 people aged 20–49 years, and between 250,000 and 600,000 people aged 50+ in England may be autistic but undiagnosed.

Implications of all the available evidence

Community case-finding studies indicate that the true prevalence of autism has been stable over the last 70–80 years. Therefore, these findings highlight continuing inequalities in access to autism diagnostic assessments for adults in England, and suggest that policy initiatives designed to address underdiagnosis in adults have not yet been effective.

Inpatient Discharge Data Confirm Increase in Autism Prevalence

In The Politics of Autism, I discuss evaluation, diagnosis, and the uncertainty of prevalence estimates.

"Epidemiologic Patterns of Autism Spectrum Disorder in Pediatric Inpatients in the United States, 1997–2019," by Stanford Chihuri, Ashley Blanchard, Carolyn G DiGuiseppi & Guohua Li

Journal of Autism and Developmental Disorders (2023) Cite this article

Abstract

The reported prevalence of autism spectrum disorder (ASD) has more than tripled in the past two decades in the United States, due in part to improved screening and diagnostic techniques. Epidemiologic data on ASD, however, are largely limited to population-based surveillance systems. We examined epidemiologic patterns in ASD diagnoses among inpatients aged 1–20 years, using data from the Kids’ Inpatient Database (KID) from 1997 to 2019. ASD cases were identified using ICD-9-CM and ICD-10-CM codes. Of 9,267,881 hospital discharges studied, 110,090 (1.19%) had a diagnosis of ASD. The prevalence of ASD was higher among males compared to females (1.53% vs. 0.54%) and was highest among non-Hispanic Whites (1.28% vs. 0.95% in non-Hispanic Blacks, 0.94% in Hispanics, and 1.18% in Other races). ASD prevalence increased from 0.18% to 1997 to 3.36% in 2019 (Z= -273.40, p < 0.001). The absolute increase was higher among males compared to females (0.26–4.90% vs. 0.08–1.77%) and among non-Hispanic Whites (0.18–2.88%) compared to non-Hispanic Blacks (0.23–2.72%), Hispanics (0.14–2.60%), and Other races (0.19–2.97%). The epidemiologic patterns of ASD based on inpatient data are generally consistent with reports from the community-based autism surveillance system. Our findings indicate that KID and other health services data might play a complementary role in ASD surveillance.

Conclusion

In a national study of pediatric inpatient discharges, there was a marked increase in ASD prevalence, with more rapid increase among younger birth cohorts, males, and non-Hispanic Whites. The prevalence of ASD followed a similar pattern to the ADDM Network- reported prevalence over time. Prevalence estimates for all age groups are important for informing public policy, allocating resources and services, and raising awareness. Our findings demonstrate the potential utility of hospital discharge record data for ASD surveillance.