A new U.S. Centers for Disease Control and Prevention (CDC) report found a 15% increase in the prevalence of autism spectrum disorder (ASD) since the last report came out two years ago, marking the highest prevalence rate since the CDC began tracking ASD in 2000.
Autism spectrum disorder is an umbrella term for a number of disorders that fall within the autism spectrum, generally characterized by social and communication impairments, combined with limited interests and repetitive behaviors.
Fragile X syndrome is the most common-known single-gene disorder, and accounts for about 2-3% of all ASD cases.
The CDC report, titled “Prevalence of Autism Spectrum Disorder Among Children Aged 8 Years — Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2014,” although published in 2018, refers to data from 2014.
It was written with contributions from researchers at the Johns Hopkins Bloomberg School of Public Health.
Total ASD prevalence among 8-year-old children in 2014 was one in 59 (or 1.7%). However, as was seen in earlier reports, boys were four times more likely to be identified with autism spectrum disorder than girls — the prevalence of ASD in boys in 2014 was one in 38 (2.7%) and in girls was one in 152 (0.7%).
For the 2018 report, data was collected from 11 regional monitoring sites, part of the Autism and Developmental Disabilities Monitoring (ADDM) Network in 11 U.S. states.
This marks the sixth ADDM Network report, with the same methodology used for more than 10 years.
Estimated prevalence rates of ASD in the country appear to be increasing, with data from earlier reports accounting for:
- one in 150 children in 2000 and 2002;
- one in 110 children in 2006;
- one in 88 children in 2008;
- one in 68 children in 2010 and 2012;
- one in 59 children in 2014.
The report also found that racial and ethnic disparities were decreasing. Among white children, ASD prevalence was about 20-30% higher than black children in earlier reports. In the latest report, the gap between white and black children dropped to 7%.
However, non-white children with autism spectrum disorder are still being diagnosed and evaluated at older ages, according to the report.
Approximately 70% percent of children with ASD had borderline, average, or above-average intellectual ability, a proportion higher than that found in previous reports.
“The estimated overall prevalence rates reported by ADDM at the monitoring sites have more than doubled since the report was first published in 2007,” Li-Ching Lee, PhD, a psychiatrist epidemiologist with the Bloomberg School’s departments of epidemiology and mental health and the principal investigator for Maryland ADDM, said in a press release.
“Although we continue to see disparities among racial and ethnic groups, the gap is closing,” Lee said.
Other measures remained similar, including a greater likelihood of boys being diagnosed with ASD, the age of earliest comprehensive evaluation, and the presence of a previous ASD diagnosis or classification — seen in about 80% of the children.
Of note, the prevalence of autism spectrum disorder in Maryland was higher than in the network as a whole, a fact that may be related to the late evaluation of these children despite developmental concerns registered in their records.
“This lag may delay the timing for children with ASD to get diagnosed and to start receiving needed services,” Lee said.
The CDC recommends that parents be particularly aware of their children’s development and act in a timely manner to get a child seen by a specialist if they are concerned.
The CDC has put together free checklists for patients, physicians, and childcare providers. They can be found here.
A copy of the Community Report with individual state statistics can be found at this link.