I've got Asberger's syndrome and he's got mine

Simon Baron-Cohen, Borat's cousin and irritating autism guru, complains about the forthcoming deletion of Asberger's Syndrome from DSM.

....a committee of experts charged with revising the manual has caused consternation by considering removing Asperger syndrome from the next edition, scheduled to appear in 2012. The committee argues that the syndrome should be deleted because there is no clear separation between it and its close neighbor, autism. The experts propose that both conditions should be subsumed under the term “autism spectrum disorder,” with individuals differentiated by levels of severity. It may be true that there is no hard and fast separation between Asperger syndrome and classic autism, since they are currently differentiated only by intelligence and onset of language. Both classic autism and Asperger syndrome involve difficulties with social interaction and communication, alongside unusually narrow interests and a strong desire for repetition, but in Asperger syndrome, the person has good intelligence and language acquisition.

Which sums up my reasons for having no respect for Baron-Cohen: he can't separate, even conceptually, intelligence and language. They come as a unit. He sees two conditions - no intelligence and no language, autism; intelligence and language, Asbergers - when the words he uses virtually mandate at least three - no intelligence/no language, intelligence/language, [no intelligence/language], intelligence/no language. Either these are separate qualities or they aren't.

....history reminds us that psychiatric diagnoses are not set in stone. They are “manmade,” and different generations of doctors sit around the committee table and change how we think about “mental disorders.” This in turn reminds us to set aside any assumption that the diagnostic manual is a taxonomic system. Maybe one day it will achieve this scientific value, but a classification system that can be changed so freely and so frequently can’t be close to following Plato’s recommendation of “carving nature at its joints.”

Part of the reason the diagnostic manual can move the boundaries and add or remove “mental disorders” so easily is that it focuses on surface appearances or behavior (symptoms) and is silent about causes. Symptoms can be arranged into groups in many ways, and there is no single right way to cluster them. Psychiatry is not at the stage of other branches of medicine, where a diagnostic category depends on a known biological mechanism. An example of where this does occur is Down syndrome, where surface appearances are irrelevant. Instead the cause — an extra copy of Chromosome 21 — is the sole determinant to obtain a diagnosis. Psychiatry, in contrast, does not yet have any diagnostic blood tests with which to reveal a biological mechanism.

Yes, but there are tradeoffs. In diagnoses where surface appearances and symptoms are irrelevant, the diagnosis doesn't necessarily say anything about surface appearances or symptoms. It's possible to say that you can't be sick with TB without the presence of the TB bacteria, but you can have TB bacteria without being sick, and at least 90% of positive tests do. Is SBC really prepared to face a situation where (say) 30% of the population has the diagnostic markers of autism but only 0.5% show symptoms?

Mind you, it does look rather as if this is mere handwaving, because he's not proposing to apply any physical tests, he's just opposing the deletion of one symptom-based subdivision of a symptom-based diagnosis.

We don’t yet know if Asperger syndrome is genetically identical or distinct from classic autism, but surely it makes scientific sense to wait until these two subgroups have been thoroughly tested before lumping them together in the diagnostic manual. I am the first to agree with the concept of an autistic spectrum, but there may be important differences between subgroups that the psychiatric association should not blur too hastily.

Yes, there may be important differences between subgroups (even if, for the sake of argument, you accept the existence of an overriding condition rather than a flotilla of quite different conditions sharing common symptoms) but in order to make the point you're actually making you surely have to make some attempt to demonstrate that Asbergers is in fact in some way a distinct subgroup rather than a point on a spectrum. I myself abominate the notion of a spectrum, which in practice reduces to the good oldfashioned ladder of creation from the stupid to the like us, I prefer to place cases in n-dimensional space and look for groupings, but SBC doesn't, so where's the Asbergers distinction?

My colleagues and I recently published the first candidate gene study of Asperger syndrome, which identified 14 genes associated with the condition.

Horse feathers. The study compared a normal population with an Asberger population, on a number of autistic traits, which means that any associations (described as 'above chance', which doesn't sound as if they're particularly strong) could just be with autism spectrum disorder, not Asberger's specifically. Not even close.

Joke in headline - hat tip to S. J. Perelman.