Twenty years of autism surveillance: What are the numbers telling us? 

Richard E Frye, MD, PhD
Autism Discovery and Treatment Foundation, Phoenix AZ
Rossignol Medical Center, Phoenix AZ
Principal Investigator, Southwest Autism Research and Resource Center, Phoenix, AZ (
President, Autism Discovery and Treatment Foundation, Phoenix, AZ (

It has now been 16 years since the Centers for Disease Control and Prevention (CDC) started reporting the prevalence of autism spectrum disorder (ASD) in a standard model through the Autism and Developmental Disabilities Monitoring (ADDM) Network on regular basis. With almost every report, the prevalence has continued to increase. The CDC examines prevalence at two ages, the prevalence of ASD for 4-year-old and 8-year-old children in a particular year. For 8-year-old children, the prevalence of ASD has risen from 1:150 for 8-year-olds in 2000 to now 1:36 for 8-year-old children in 2020. The reason for the continuous rise in ASD prevalence remains elusive. Regardless of the reason for this increase, one fact is obvious — we, as a nation, have made no progress in reducing the number of children that develop this disorder. So, what do the new numbers tell us besides the fact that we need to do better?

The first interesting findings from these studies are the changes in the prevalence in Black and Hispanic subgroups. These groups had been long suspected to be underdiagnosed but this disparity in the prevalence began to narrow in 2014 and in 2020 appears to have reversed. Indeed, the prevalence increase in Asian, Black, and Hispanic children was twice as large as those of White children from 2018 to 2020 with White children having lower prevalence than other groups for the first time. This could reflect the success of ongoing efforts to improve screening, diagnosis, and education in traditionally underserved populations. However, these groups also tend to have disparities in other conditions that might influence the development of ASD. Specifically, these groups tend to have poorer nutrition and live in areas which have greater exposure to environmental agents, such as pesticides, air pollution, etc., which have been linked to an increased risk of ASD. It will be interesting to see whether further research finds that this increase is due to better identification of children in these traditionally underserved groups and why there is a higher rate of ASD in these children.

The second interesting finding from these studies is the state-to-state variation in the identification, diagnosis, and engagement of special education. The ADDM identifies a child as having ASD if their records have either a diagnostic statement, a special education eligibility statement, or a diagnostic code. Only 23.3% had all three of these components and 9.8% only had a diagnostic code without a supporting diagnostic statement or special education eligibility. Some states like Missouri and New Jersey were very good at having a diagnostic statement in the record (>90%) but poor at having special education eligibility statement while other states like California were good at having high rates of all three components. Why is this important? Unfortunately, in many states, a diagnosis of ASD is not sufficient to receive the services needed and many states have specific requirements to receive special education services. This can be very frustrating for families as they try to navigate the complex system to find the services their children need. Some states make a significant effort to support integrated diagnostic and evaluation practices to streamline this process for families but in many states, the system is fractured. I believe this reflects an area that needs significant help, especially since it has long been known that interventions are most helpful when started as early as possible. 

Other interesting findings were also found in these studies. The authors used the data from the two age groups to demonstrate that identification of ASD by 4 years of age is improving overall. Also, for the first time, the prevalence of ASD in girls has risen above 1%.  

These surveillance studies are important, but hopefully, they will lead to further research delving into why these numbers continue to increase, and what we can do to reverse the trend and get support for families and their children who need us to care.


2023 Scientific Report

2023 Community Report

TACA’s About Autism Page

2 thoughts on “Twenty years of autism surveillance: What are the numbers telling us? 

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  1. You ever think about what is put on food when it is being processed and grown and the amout of drugs people now take for day to day life. Real rocket science.

  2. The only silver lining I can see in this is that it incentivizes more organizations and companies to find more effective medical/drug treatments because there’s likely to be a greater return on investment.

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