Three studies published between last summer and this month conclude that the DSM-5 criteria for ASD are too strict, but that a few small changes would make them appropriately inclusive. One might think that the APA would conduct such research themselves, but studies that explicitly compare DSM-IV and DSM-5 criteria are not an official part of the revision process. Rather, researchers who are not helping revamp the DSM, but were interested in how the new edition will change psychiatric diagnosis, decided to find out for themselves.
Marja-Leena Mattila of the University of Oulu in Finland conducted the only epidemiological study published so far that explicitly compared the two editions' criteria for autism. (Mattila used DSM-5 criteria posted to the DSM-5 Development Web site in February 2010; the criteria have the same basic structure as the new specifications posted in January 2011, but they are far less detailed and descriptive.) In her study, Mattila surveyed a sample of more than 5,000 Finnish schoolchildren and identified 26 eight-year-olds with an IQ of 50 or higher who qualified for autistic disorder in the DSM-IV. Of those 26, only 12 qualified for ASD in the DSM-5. But when Mattila lowered the threshold for ASD by requiring only two of the three symptoms in the social interaction and communication group, 25 of the 26 children qualified for ASD in the both the DSM-5 and its predecessor. Her work appears in the June 2011 issue of the Journal of the American Academy of Child and Adolescent Psychiatry.
Similarly, Thomas Frazier of the Center for Autism at the Cleveland Clinic performed a series of statistical analyses on symptom reports from nearly 7,000 ASD children, looking for the symptoms that appeared together most frequently. When he programmed a computer to figure out what kind of diagnostic model best reflected the naturally occurring clusters of symptoms, Frazier found that a model with two groups of symptoms—just like the one in the DSM-5—captured how the symptoms clustered in the children better than the DSM-IV or any other model. He also found that the DSM-5 model misdiagnosed autism in only 3 percent of the children, whereas the DSM-IV model misdiagnosed autism in 14 percent. When Frazier relaxed the DSM-5 requirements from five out of seven criteria to four out of seven, he brought back about 12 percent of ASD children that the model originally neglected.
William Mandy of University College London also used statistical analyses to evaluate the DSM-5 criteria and concluded that the two-group DSM-5 model is overall more accurate than the three-group DSM-IV model, but a little too restrictive. Both Frazier's study and Mandy's study are published this month in the Journal of the American Academy of Child and Adolescent Psychiatry.
"They got the major changes right," Mandy says of the APA. "But recent evidence shows that borderline people might miss out on a diagnosis in DSM-5 because they don't have clinical levels of some symptoms, such as repetitive behavior. The real issue is threshold." Not all psychiatrists agree that the stricter DSM-5 criteria should be relaxed, because they think that many people currently diagnosed with Asperger's or PDD-NOS do not in fact have autism and that the new definition of ASD should not include these people. Some parents of children with severe autism are also in favor of stricter criteria, arguing that children who are most in need should receive state services over others with milder symptoms.
Darrel Regier, vice chair of the DSM-5 Task Force, says that he is well aware of the recent studies and that the committee will consider whether they need to revise the DSM-5 criteria for ASD even further. The APA is supposed to finalize all changes to the DSM this year and publish the new edition in May 2013. When asked if he thinks the APA can adjust the revisions to criteria not only for ASD, but for all the other disorders in the DSM-5 by the end of this year, Regier says "there is plenty of time."