A study conducted by the Centers for Disease Control and Prevention and autism groups concluded that the new diagnostic criteria from the Diagnostic and Statistical Manual of Mental Disorders-5 (DSM-5) could decrease the amount of diagnoses of autism spectrum disorder. The DSM defines and classifies all mental illnesses and is widely used by practitioners and insurance companies to determine what conditions are considered abnormal.

Published in JAMA Psychiatry, the researchers reviewed the fifth edition of the DSM, implemented in May of 2013, and found that out of 6,577 eight-year-olds who were part of the population diagnosed with autism-spectrum-disorder defined by the old guidelines, 5,339, or 81 percent, will keep their diagnosis under the new guidelines. Using the DSM-5 criteria, they discovered that the prevalence of autism-spectrum disorder in 2008 would have been 1 per every 100 people compared with the 1.13 per 100 people who were diagnosed with the DSM-4 criteria.

The new DSM-5 criteria for autism may be more rigorous than the previous criteria, said study researcher Matthew Maenner, of the Centers for Disease Control and Prevention. "Most of the children who didn't make the cut, they didn't miss by a lot," Maenner said. "They only needed one additional criterion to meet the DSM-5 definition. They had four of the five."

Autism Speaks is surveying parents to find how the changes are affecting their children with autism.

"What we've seen from the first 600 persons participating in the survey, is that there is a percentage of individuals being asked to be re-evaluated by school districts or insurers using DSM-5 criteria," Michael Rosanoff, associate director of public health research at Autism Speaks, a nonprofit advocacy group said.

Maenner believes the change in criteria will be challenging to compare newer estimates of autism rates to older standards. However, Maenner believes this study “is a step we can take to begin to understand how to put those numbers in context.”

Additional Resources:

http://www.autismspeaks.org/what-autism/dsm-5