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Friday, June 7, 2019

Introduction to Classification of psychiatric disorders and their principal treatments


By: Peter Tyrer and Kenneth R. Silk

Why, you may well ask, has a book about treatment found it necessary to begin with a section on diagnosis? Since the introduction of DSM–III (American Psychiatric Association, 1980), diagnosis has seemed to become the ‘holy grail’ of psychiatry. Yet currently, diagnosis is in the doghouse, as the quotations above, spanning nearly a hundred years, illustrate. But, even though we despair at regular intervals, we continue to want a nice clean system that allows psychiatric patients to be pigeon-holed by clever clinicians who then have both an explanation of a disorder and its solution. For the hope has always been that if a specific diagnosis is made correctly, that the proper and best treatment will follow almost automatically.

If only psychiatry were that easy! If it was, then that book would not be necessary, for from the proper diagnosis would flow the essential treatment. But in psychiatry, and we would venture to say in most other specialties as well (though perhaps not so readily acknowledged by other practising physicians as in psychiatry), the diagnosis not only does not point directly towards treatment but can become a source of major conflict between clinicians and patients, and lead to allegations of the generation of stigma, labelling and other counter-productive arguments.

Then why do we persist with trying to refine and rework diagnoses and diagnostic manuals, and furthermore, why give it pride? In psychiatry, the path from correct diagnosis to correct explicit treatment is neither straight nor unambiguous and probably depends upon a number of different factors. The first factor might be the way diagnoses have evolved or developed in psychiatry, especially since, but not solely because of, the development of the editions of the DSM or the ICD that were advanced in the mid 1970s and became established as the DSM–III in 1980 (American Psychiatric Association, 1980) and the ICD–9 (World Health Organization, 1975, 1978) in 1975 with its clinical modification in 1978.

Both of these then new iterations of prior diagnostic manuals profoundly changed the way psychiatrists approached diagnosis on both sides of the Atlantic. Rather than making a diagnosis based upon a number of different factors that included not only the ‘chief’ or presenting complaint, the specific symptoms that surrounded or accompanied the chief complaint, and the associated physiological and somatic concerns and complaints, while also considering the patient’s capacity for empathy, the nature of his rapport or stance or ‘posture’ in relationship to the interviewing physician, the congruence of his affect with the content of his speech, and his ability to step back and view and comment on his own behaviour, the psychiatrist using the ‘new’ post 1980s approach basically needed to consider only the chief complaint with its accompanying symptoms, since together they were thought to be part of the package of the patient’s overall psychophysiological, i.e. biologically determined, disorder. Empathy, relationship to the interviewer or to other people, capacity for insight, even motivation to change took on less significance, if any at all, as the new psychiatry, determined to look and feel like the rest of medicine, moved rapidly down the one diagnosis-one treatment road. If you got the diagnosis right, the choice of treatment would be, as they say, a ‘no-brainer’.

This process can be compared with travelling on an expanding limited-access highway system where all you needed to know was what exit to take. Get on the correct road and take the correct exit and you would speedily be led to your desired destination. Get on the right diagnostic road and you will soon arrive at your destination, the right treatment. If the things that you needed at a specific exit were not that close by and to make things even clearer and more precise with less chance for error, more exits leading to more highways could be built (or more diagnostic entities created) so that you could arrive at your destination even more rapidly and efficiently. Of course, one of the problems with the interstate highway system, at least in the USA, is that, from the highway, all the roads look the same; and even when you get off the highway, the interchanges, with their almost standardized or perhaps operationalized conglomeration of fast food chains and service stations (symptoms and checklists), all, at least from some distance, look the same as well. You get little impression of the people who live and work in that particular area. But venture perhaps no more than a mile from the interstate, and you will find towns and cities and country roads that carry with them the specific distinction, flavour, and even peculiarity of the people and the geographical areas that you are passing through. Such a diversion from the interstate may not get you to your destination sooner, and it may not even appear initially to lend any valuable information to the journey. Yet it may convey a completely different and more complex sense experience and, in turn, appreciation of the trip that the shorter, faster, more direct route, the route the map searches on the computer produce when queried, places little or no value upon. The second factor is related to other specific ideas about psychiatry, diagnosis and biology that developed throughout the 1970s. There evolved a number of ideas that took hold beginning in the late 1960s that were to change psychiatry and the diagnostic process profoundly.

There developed the belief that we could, with enough expertise and diagnostic rigidity, isolate very specific diagnostic entities in psychiatry; and further that these specific entities were separate and distinct from other diagnostic entities. For example, there evolved the idea that depression, i.e. mood disorders, could clearly, in many cases, be distinguished from anxiety disorders. There was even a specific test developed, the dexamethasone suppression test (DST), that was purported to be able to distinguish true melancholic depression from other entities. The title of that seminal paper in 1979, ‘A specific laboratory test for the diagnosis of melancholia’ conveys a good deal more about the wishes, not only of the authors, but of psychiatry in general, that there be specific laboratory tests that could help psychiatrists determine which patients had which diagnoses (Carroll et al., 1981). If there was a biological or laboratory test that could help support that distinction, then psychiatry could have ‘real’ rather than imagined diagnoses (even though in most of medicine, there are actually very few diseases that have specific or pathognomonic tests that support their existence unequivocally).

This is in no way to deny that the DST has gone on to become an important and useful measure of hypothalamic-pituitary-adrenal (HPA) activity and has led to many important areas of research and explorations into brain neurochemistry. And while the HPA axis is still thought to be overactive in some mood-disordered states, we now know that HPA overactivity may be a more general measure of an individual’s reaction to stress and stressors rather than a specific laboratory test that reveals the presence of a specific mood disorder, or a mood disorder at all. What was originally proposed to be a specific laboratory test for a specific diagnostic entity turned out to be a laboratory test that cut across many of these so-called specific diagnostic groupings and appeared to be disordered across a number of conditions that all seemed to be linked together because of their relationship and reaction to stress. Stress certainly plays a role in many disorders, psychiatric as well as more purely medical.

References

Peter Tyrer and Kenneth R. Silk, Cambridge Textbook of Effective Treatments in Psychiatry, Cambridge University Press 2008.

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