Updated: Jan 15, 2020
Go to three different psychiatrists, there’s a reasonable chance you’ll end up with three different diagnoses. To be fair, Medicine is an inexact science (or art), and this happens in other fields as well from time to time. But doctors in other specialties agree a lot more often. High blood pressure is high blood pressure. Diabetes is diabetes. A broken leg is a broken leg.
The problem is that in psychiatry we are dealing with conditions that can’t be easily measured. Despite all the excitement in advancing understanding of genetics and biochemistry, and fancier and fancier brain scans, there are virtually no objective tests that can give an accurate psychiatric diagnosis. This probably will change over time for some conditions, but we aren’t there yet.
Psychiatric researchers are left to devise various rating scales that are quite subjective (both from the patient’s point of view and the clinician’s point of view). If you look at the Diagnostic and Statistical Manual of Mental Disorders – considered by many to be the “bible of psychiatry” – you’ll find that different diagnoses consist of nothing more than symptom checklists. Check enough of the boxes, and you qualify for the diagnosis. If you ever get a chance to take a look at the DSM, you’ll see how subjective some of these checklists are.
Where do these checklists come from anyway? If there aren’t objective lab tests, how do psychiatrists define diagnoses? How do they come up with their criteria?
Basically, by committee. Leading psychiatrists in the field sit around and argue about what should be a diagnosis, what shouldn’t, and what the criteria should be. Eventually, their consensus decision is published in the newest version of the DSM. Incidentally, with each revision of the DSM, there will be new diagnoses added and existing ones removed, sometimes seemingly at random.
If this all sounds a bit on the arbitrary side, it’s because it is. Moreover, lots of psychiatrists practicing in the field disagree with DSM criteria or even the validity of certain diagnoses. This of course is the cause of considerable confusion and frustration to patients, the public, and practitioners themselves.
To be fair, at this point in time, without objective laboratory measurements, the current system of defining diagnoses is probably the best we can do. Whether or not you agree with how the DSM defines a particular diagnosis, there aren’t a lot of alternative ways of going about things.
Given that the diagnostic system seems to be on shaky ground, is there any point to defining psychiatric conditions at all?
For some conditions, the answer is yes. Some psychiatric illnesses (schizophrenia and classic bipolar disorder come to mind) are so distinctive that they undoubtedly represent common pathological process(es). Once you’ve seen them, you don’t forget them. It’s likely that in the future we’ll have objective tests that will help us diagnose these illnesses more definitively. In the meantime, these diagnoses are useful in talking about conditions that cause the same problems, respond to the same treatment, and run the same course.
Some diagnoses such as major depression and OCD also are distinctive enough to be useful. Very often, however, there are milder forms that would probably be better described as being psychiatric “traits” rather than “diagnoses”. They don’t seem to describe discrete conditions but rather tendencies.
Some diagnoses – to this writer at least – don’t make any sense at all. I have a particular problem with “Oppositional Defiant Disorder,” which according to the DSM includes signs of being “angry or irritable,” “argumentative or defiant,” and “vindictive”. There are lots of reasons kids can be all of these things, some related to their own character, some related to their parenting, and some related to their environment. To me, unlike schizophrenia, this “diagnosis” serves no particular value. It does not describe a common cause, suggest a common treatment strategy, or run a common course. I’ve seen plenty of oppositional kids but never believed that this somehow represents a distinct “disorder.” But different psychiatrists have different opinions, and we are all working with limited information.
Nevertheless, there is one non-clinical but important reason to use DSM diagnoses: payment. Insurances won't pay for treatment without a diagnosis code. Because so many people present with symptoms that don't fit neatly into DSM categories, psychiatrists are often left picking the closest diagnosis to what they are seeing, which is a suboptimal but necessary practice.
To summarize, psychiatrists are stuck with a much less solid diagnostic system than medical practitioners in other fields. The system is still useful as long as we remain attuned to its limitations. Fortunately, as will be discussed in a subsequent post, psychiatrists are much better at treating symptoms than conditions anyway.
To put it another way, finding the “right” diagnosis doesn’t matter much in terms of treatment anyway!