After years of escalating growth, a new study looking at data from the U.S. Centers for Disease Control and Prevention suggests that autism rates could drop off thanks to new diagnostic criteria for the developmental disorder.

In a review of surveillance data on 8-year-olds with autism collected by the CDC in 2006 and 2008, researchers found that nearly 1 in 5 of the youngsters would not have qualified for a diagnosis on the autism spectrum under updated criteria in the latest edition of the Diagnostic and Statistical Manual of Mental Disorders.

Last year, a fifth edition of the DSM was published which included sweeping and controversial changes to the diagnosis of autism. The new version of the manual altered the diagnostic criteria and did away with Asperger’s syndrome, childhood disintegrative disorder and pervasive developmental disorder, not otherwise specified, instead creating an umbrella classification of “autism spectrum disorder” with clinicians indicating a level of severity.

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The change was met with significant trepidation among many in the autism community who were concerned that individuals might be stripped of their diagnosis and lose needed services. In response, those behind the DSM update appended the autism entry with a note indicating that people with an existing diagnosis on the spectrum should retain the label.

In an effort to assess how this change could impact autism prevalence going forward, researchers looked at medical and educational records for 6,577 kids diagnosed with autism under the previous edition of the DSM who were part of the CDC’s surveillance efforts. They found that only 81 percent of the children would qualify for an autism diagnosis under the DSM-5 definition, according to the study published Wednesday in JAMA Psychiatry.

“Autism spectrum disorder prevalence estimates will likely be lower under DSM-5 than under DSM-IV-TR diagnostic criteria, although this effect could be tempered by future adaptation of diagnostic practices and documentation of behaviors to fit the new criteria,” the authors wrote.

Many of the kids who no longer appeared to qualify were missing just one criteria for the diagnosis, said Matthew J. Maenner of the CDC’s National Center on Birth Defects and Developmental Disabilities who led the study.

“It is important to point out that we cannot predict what will happen in the future with how individuals with ASD are diagnosed, or how (or when) professionals will adapt to the new diagnostic criteria,” Maenner said.