Now, for the first time, the Centers for Disease Control and Prevention is factoring the changing definition of autism into its regular tracking of autism prevalence.
Figures released in April show that 1 in 59 children have autism — an increase from reports two years ago that found 1 in 68 children were on the spectrum. However, the latest numbers, which rely on data collected on over 300,000 children who were 8 years old in 2014, are based on the older definition of autism.
In the same report, the CDC then evaluated the children under the newer DSM-5 criteria, finding that 18 percent fewer would qualify for an autism diagnosis. Using the updated definition and also including children who had previously received a diagnosis of autism, 4 percent fewer children were found to have autism.