A new report by the U.S. Centers for Disease Control and Prevention (CDC) found no increase in the prevalence of autism spectrum disorder (ASD) compared to two years ago.
The findings show that the ASD rate remains the same at one in 68 children (or 1.46 percent). Boys are still 4.5 times more likely to be identified with ASD than girls at a rate of one in 42 compared to one in 189 among girls.
Rates of ASD have been steadily rising for decades, but researchers have been unsure whether this increase is due to more children being diagnosed with ASD or if actual cases are increasing or a combination of both.
The CDC’s Autism and Developmental Disabilities Monitoring Network (ADDM) has used the same surveillance methods for more than a decade. Previous prevalence rates of ASD in the U.S. are as follows:
- one in 68 children in the 2014 report that looked at 2010 data;
- one in 88 children in the 2012 report that looked at 2008 data;
- one in 110 children in the 2009 report that looked at 2006 data;
- one in 150 children in the 2007 report that looked at 2000 and 2002 data.
For the new report, the CDC gathered data at 11 regional monitoring sites that are part of the Autism and Developmental Disabilities Monitoring (ADDM) Network in the following states: Arkansas, Arizona, Colorado, Georgia, Maryland, Missouri, New Jersey, North Carolina, South Carolina, Utah, and Wisconsin.
The researchers say it is too early to tell if the overall prevalence rate has stabilized because the numbers vary widely across ADDM communities. In communities where both health and education records were reviewed, the rates are from a low of 1.24 percent in parts of South Carolina to a high of 2.46 percent in parts of New Jersey.
Certain ASD trends in the latest CDC report data remain consistent as well, such as the greater likelihood of boys being diagnosed with ASD. Differences in prevalence according to race/ethnicity still persist, as well as the age of earliest comprehensive evaluation and presence of a previous ASD diagnosis.
Specifically, non-white children with ASD are being identified and evaluated at a later age than white children. The majority of children identified with ASD by the ADDM Network (82 percent) had a previous ASD diagnosis or a special educational classification.
“Although we did not observe a significant increase in the overall prevalence rates in the monitoring sites, we continue to see the disparity among racial and ethnic groups,” said Dr. Li-Ching Lee, Ph.D., Sc.M., a psychiatric epidemiologist with Johns Hopkins Bloomberg School’s departments of Epidemiology and Mental Health, and the principal investigator for the Maryland-ADDM.
“For example, in Maryland, we found that Hispanic children were less likely to be evaluated for developmental concerns and therefore less likely to be identified.”
Furthermore, in Maryland, a large majority of children (95 percent) identified with ASD had a developmental concern in their records by age three, but only 55 percent of them received a comprehensive evaluation by age three.
“This lag may delay the timing for children with ASD to get diagnosed and receive needed services,” Lee says.
While the causes of autism are not completely understood, research has shown that both environment and genetics play a role. There is no known cure. The CDC suggests that parents track their child’s development, act quickly and get their child screened if they have a concern.