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Can Rise in Autism Be Explained by Broadened Diagnosis?

New study out of Denmark suggests that autism’s rising prevalence may stem, in part, from changes in diagnostic criteria
January 06, 2015

A report in this week’s JAMA Pediatrics revisits the suggestion that expanded diagnostic criteria may be a major contributor to autism’s rising numbers.

The study tracked 677,915 Danish children over several decades. It found that a significant rise in autism prevalence followed a 1994 broadening of Denmark’s diagnostic criteria for the disorder. The Danish study does not discount other factors that may be contributing to the dramatic rise in autism prevalence over recent decades.

“Part of the change in prevalence over time is clearly associated with changes in diagnostic criteria,” says Michael Rosanoff, Autism Speaks’ director of public health research. “But this explains only part of the increase,” Rosanoff also provided context for the findings in a related article on – agreeing with the study authors that more research is urgently needed into the environmental factors that likewise appear to be contributing to the continuing rise in prevalence.

TIME asked Rosanoff whether another change in estimated prevalence may result from last year’s overhaul of the criteria used to diagnose autism in the United States. (See Autism Speaks coverage of the new DMS-5 criteria here).

“Our concern has been that the constricting of the criteria would in fact artificially reduce the prevalence of autism,” Rosanoff told TIME. “The DSM-5 has not been in play for long enough and there’s ongoing research looking at how prevalence is changing and access to services.”

Autism Speaks and the CDC are collaborating on studies to track changes in reported prevalence and autism services in the wake of the new DSM-5 diagnostic criteria. Learn more about these studies here.