The New York Times reports New Definition of Autism May Exclude Many, Study Suggests . The study is not published yet and was presented at a conference in Iceland.
The Times reports:
The study results, presented on Thursday at a meeting of the Icelandic Medical Association, are still preliminary, but they offer the latest and most dramatic estimate of how tightening the criteria for autism could affect the rate of diagnosis. Rates of autism and related disorders like Asperger syndrome have taken off since the early 1980s, to prevalence rates as high as one in 100 children in some places. Many researchers suspect that these numbers are inflated because of vagueness in the current criteria.
The conference program doesn’t have abstracts, just paper titles. Prof. Volkmar had two talks on autism: “The Changing Face of Autism: An Introduction and Overview” and “Understanding Autism: Implications for Health Care”. This leaves us with the Times article as our source for information.
According to the Times:
In the new analysis, Dr. Volkmar, along with Brian Reichow and James McPartland, both at Yale, used data from a large 1993 study that served as the basis for the current criteria. They focused on 372 children and adults who were among the highest-functioning and found that over all, only 45 percent of them would qualify for the proposed autism spectrum diagnosis now under review. The focus on a high-functioning group may have slightly exaggerated that percentage, the authors acknowledge.
Dr. Lord said that the study numbers are probably exaggerated because the research team relied on old data, collected by doctors who were not aware of what kinds of behaviors the proposed definition requires. “It’s not that the behaviors didn’t exist, but that they weren’t even asking about them — they wouldn’t show up at all in the data,” Dr. Lord said.
The question of how the DSM 5 will change the criteria for how autism is defined has been a subject of great speculation and some study. One can find parents claiming that the DSM 5 is designed to redefine autism as only “high functioning” all the way to autistics worried that many with Asperger syndrome will no longer be classified as autistic.
The results presented by Prof. Volkmar would suggest that “classic” autism, PDD-NOS and Asperger syndrome would all see significant changes:
The likelihood of being left out under the new definition depended on the original diagnosis: About a quarter of those identified with classic autism in 1993 would not be so identified under the proposed criteria; about three quarters of those with Asperger’s would not qualify; and 85 percent of those with P.D.D.-N.O.S. would not.
As noted above, this is not the first study to consider the DSM 5 and autism. For example, a group from Finland published Autism spectrum disorders according to DSM-IV-TR and comparison with DSM-5 draft criteria: an epidemiological study . they found the DSM-5 draft criteria were ” less sensitive in regard to identification of subjects with ASDs, particularly those with Asperger’s syndrome and some high-functioning subjects with autism.”