I had an excellent discussion with a colleague this morning, wherein we both lamented the sad state of psychiatry and psychiatric diagnostic practice. One of the things I mentioned (and thought I’d throw on here today, in the spirit of Friday Filosophy being whatever sort of finking I want it to be) was about diagnostic criteria creating disorders, rather than the other way around.
In order to ensure we are all talking about the same things, in the absence of definitive blood tests or imaging, or anything else, we have lists of diagnostic criteria (the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders – coming up to v.5 – and the (European) International Classification of Diseases – up to its 10th iteration I think). These criteria should serve the purpose of ensuring that when I say someone has schizophrenia, for instance, my colleagues know pretty much what set of problems the patient has. (Of course, you can actually have two patients who both meet diagnostic criteria – with enough of the symptoms on the list to make a diagnosis – but sharing not one single symptom, so arguably there’s a pretty fundamental flaw.)
The issue I raised this morning though was with what order we’re working in when we identify these criteria. If you were to make up a list of characteristics that made up something you called Zippideedoodah disorder, and you went through the population examining enough people, you would likely find some people who displayed none of those criteria, some with a few (subthreshold) and some with many or all. The latter group you could then diagnose with zippideedoodah disorder. You might then do some studies to see if these people could be reliably identified and distinguished from people without zippideedoodah disorder. Funnily enough, because you have defined that group of people by the criteria you are using to define the disorder, the answer is likely to be the same as Obama, and Bob the Builder: “Yes we can!”
Now if we imagine something somewhat less absurd, we can see that one might well include in the criteria for the “disorder” some distress, or problems with function. Therefore one could say, it is indeed a disorder; these people have problems. You might well be able to show some treatment effect by giving them something, given that most things actually (appear to) work – for all sorts of non-specific reasons.
Presto diagnoso! A new category exists.
I’m being a little facetious of course, but note that the first DSM listed just over 100 disorders, and the DSM IV has 295 or thereabouts. There’s something funny goin’ on here, folks.
As long as we define psychiatric disorders in this way, we are likely to end up with heterogenous groups of people lumped together in invalid categories (that are almost unfalsifiable, as they are defined by the very criteria with which you assess whether people really do fit within them); this does not lend itself to delineating true illness from distress and thus moving forward as a medical specialty.
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