The way DSM-IV is formulated means there are over 2000 combinations of the 12 criteria that at the minimum threshold of six yield an autism diagnosis.DSM-5 proposes collapsing autism, Asperger's and PDD-NOS into a single "autism spectrum" category, combining and reducing criteria, vastly cutting the number of combinations that can lead to an autism diagnosis. This prompted me and my colleagues to reanalyse the DSM-IV field-trial data from 1994 for an upcoming edition of the Journal of the American Academy of Child and Adolescent Psychiatry. We found that many people, particularly the more cognitively able, would lose their diagnosis under the new regime.
What might this mean? It is possible that support for those in need will be hit, particularly in the US, where a diagnosis can trigger health insurance. Secondly, such a radical change would make it difficult to interpret the vast body of work done using DSM-IV - in 1993 there were about 390 peer-reviewed publications on autism. Last year over 2100 were produced.
Finally, the change of name to autism spectrum would suggest a broadened diagnostic concept when, if our reanalysis is correct, the opposite is the case. These are troubling issues. For such a major project, a more scientifically informed and engaged revision process is needed.
Frencesca Happe argues for change:
Anomalies in DSM-IV criteria for autism and other pervasive developmental disorders (PDDs), which includes the subgroups of autistic disorder, Asperger's and PDD-NOS, have led to clinical inconsistency, leading to wide variations in how diagnoses of these are made. One study found it was the clinic attended that best predicted which label was given.
Most people diagnosed with Asperger's actually meet the DSM-IV criteria for autism. And research suggests there are no major differences between those with early language delay and those without - the feature differentiating autism and Asperger's in DSM-IV. The current split into three categories has little support in terms of genetic, neural, cognitive and other differences. Clinicians show little agreement in telling the three apart but are good judges of what is on the autism spectrum.
There is concern that those with Asperger's or PDD-NOS might not meet ASD criteria. This is not the aim. With fellow members of the DSM-5's neurodevelopmental disorders work group, I am working hard to ensure the full autism spectrum is well recognised. We have proposed a new category of "social communication disorder" for those with some of the difficulties of autism but without rigid and repetitive behaviour - currently poorly described by the very diverse DSM-IV category of PDD-NOS. We are also seeking to aid recognition of ASD in adults coming for first diagnosis.