Prevalence of autism spectrum disorder (ASD) is rising among children in the United States, according to the latest surveillance data published by the CDC’s Autism and Developmental Disabilities Monitoring network.
Two reports describe the current state of ASD among 4-year-olds and 8-year-olds, respectively. The data draw from communities in 11 states across the country and are updated every two years. Leading the efforts to provide data from Tennessee is Zachary Warren, Ph.D., director of the Vanderbilt Kennedy Center Treatment and Research Institute for Autism Spectrum Disorders (TRIAD) and the Division of Developmental Medicine at Monroe Carell Jr. Children’s Hospital at Vanderbilt.
“These results are likely a combination of increased awareness and the advanced ways in which we evaluate children,” Warren said. “There may also be other complicated factors that are related to a true increase, but there is no one single cause. Our methodology doesn’t tell us about cause. What it does is tell us how unbelievably common ASD is in our communities.”
Trends in States and Subgroups
Overall, Warren and colleagues found 1 in 44 children in the U.S. now have an ASD diagnosis. Children are also being diagnosed earlier than ever, with 4-year-olds having a higher cumulative incidence of diagnosis than 8-year-olds.
A familiar theme included higher ASD prevalence among boys. Boys were 3.4 times (among 4-year-olds) and 4.2 times (among 8-year-olds) more likely than girls to receive an ASD diagnosis.
“These results are likely a combination of increased awareness and the advanced ways in which we evaluate children.”
Groups that had a historically lower prevalence of ASD (non-white and lower income children) saw prevalence increases in the new reports, which the researchers say suggests progress in identification.
Racial disparities leveled out among 8-year-olds, with the exception of American Indian/Alaska Native children who still experience a disproportionately higher burden of ASD than white children (29.0 versus 21.2 per 1,000 children). More Black, Hispanic and Asian 4-year-olds were classified as having ASD than white children of the same age.
ASD prevalence varied widely by state and income in both age groups. For instance, prevalence among 8-year-olds was 16.5 in Missouri and 38.9 in California (per 1,000 children). The range widened among 4-year-olds to 9.1 in Utah and 41.6 in California.
“We need to be building systems of care capable of serving 1 in 44 children.”
Early Intervention for Improved Outcomes
Warren says a shift toward earlier diagnoses described in the reports presents an opportunity for critical early intervention.
“There’s a growing evidence base that suggests providing access and support for ASD early can dramatically enhance important skills for learning and quality of life,” Warren said. “Early intervention can help support tremendous advances in terms of language and communication skills. In addition, early detection allows us to better understand, serve and support both children with ASD and their parents.”
A primary challenge to such intervention, Warren says, is infrastructure. The variability in ASD prevalence among racial, ethnic and geographic subgroups suggests strategies are still needed to ensure equitable access to evaluation and treatment. More directly, efforts are needed to address the sheer volume of young ASD patients.
“These findings push the idea, more so than anything else, that we need to be building systems of care capable of serving 1 in 44 children.”
Toward that aim, Warren says many state agencies are already using past report data to support programmatic investments targeting individuals with ASD across the lifespan. These agencies include the Tennessee Department of Education and Tennessee Early Intervention System, which both partner with TRIAD.
“It’s very likely that some of the shifts we saw in identification and service in Middle Tennessee are a direct result of that funding and broader partnerships,” Warren said.