The Validity of Psychiatric Diagnoses

Two articles listed on Google news today address the issue of validity in psychiatry. That is, they deal with the question of how ‘real’ psychiatric disorders and diagnoses are. Both articles (“Psychiatry Confuses Distress with Disorder” in the Vancouver Sun, and “If Everyone is Ill, then No one is” in the Taipei Times) address the rapid increase in psychiatric diagnoses that has occurred during the last decades. The ‘bar’, or ‘threshold’ has been lowered, they contend: more and more people are being diagnosed not because mental illness is truly on the rise, but because the scope of pathology has been widened. In other words, what used to be considered normal variation in human behavior is increasingly medicalized and pathologized. The result is over-diagnosis and over-medication. The pieces don’t address the underlying causes for this medicalization (elsewhere, writers commonly attribute it to the power of the pharmaceutical industry, and consumers’ increased familiarity with the scope of psychiatric knowledge and treatment – the latter is actually suggested in the Vancouver Sun), but both trace it back to the rapid expansion of disease categories in the DSM and its attempts to increase its scientific and medical legitimacy.

Legitimacy, in this case, involves two things: reliability and validity. The DSM is a classificatory system that attempts to diagnose disorders on the basis of presented symptoms. In the absence of medical tests, diagnosis relies on a doctor’s interpretation of standardized lists of symptomatic criteria of which a patient must meet a specified number in order to classify as ill. Horwitz and Wakefield, the authors reviewed in the Vancouver Sun, accept the reliability of these standards (that is, they accept the idea that the same patient will be given the same diagnosis by any doctor who uses the diagnostic manual), but reject their validity, because the criteria disregard the various possible etiologies of disorder. That is, while a person mourning a recent loss (not only of a loved one, but of a job perhaps, or one’s good health) might display enough ‘symptoms’ of depression for a diagnosis, this diagnosis would not be valid, because this person’s sadness is not pathological (he has good reason to be sad). According to these two authors the problem, then, is that an emphasis on reliability has compromised validity, and consequently gives rise to over-medicalization. They suggest that a bit of subjectivity might solve much of the problem: a doctor who uses the manual would do well in keeping the patient’s background in the back of his mind and making an informed, unreliable but all the more valid, judgment on the basis of these personal considerations.

For Christopher Lane on the other hand, these ‘subjective standards’ are precisely the problem. He argues that overdiagnosis arises from the incorporation of subjective judgment into the diagnostic criteria of the DSM. Who has the authority, he claims, to determine what kind of symptoms ‘impair’ normal functioning? Who has the authority to judge what constitutes that normal functioning? His proposed solution involves setting the thresholds for diagnosis much higher, thus clarifying the line between ‘mild suffering’ and ‘disorder’. This, of course, never eliminates the ‘problem’ of subjective standards. How is a higher threshold any less subjective than a lower one and what makes this writer’s standards (being an English professor) any more authoritative or valid than that of any psychiatrist? Neither seems to me ideal – a higher threshold may eliminate over-medication, but will also deprive many people who legitimately suffer from any relief. Sure, Lane makes a valid point, and over-diagnosis is certainly a problem that must be addressed, but his call to set the thresholds higher is too simplistic.
Psychiatric diagnosis is difficult, and in the absence of medical tests these diagnostic criteria are all that doctors have to work with. Of course their validity and reliability are flawed, but any medical diagnosis is ultimately guesswork to some extent. The standards used to judge blood tests are not incontrovertibly valid, either. Just like psychiatric diagnoses, they were set, at some point, by doctors who decided that a certain concentration of a particular hormone constituted the threshold for pathology, and a certain amount of antibodies indicated the presence of disease. These, too, are random numbers designed to increase the reliability of a test. They are not necessarily biological givens.

And by means of update on the gendered thought processing issue I brought up a few days ago, Science Daily published a discussion of brain transformations in schizophrenia that actually brought up the existence of slight brain differences between men and women. These differences mostly involve the circuitry that processes emotion, which (of course…) are more elaborate in women. No mention of thought processes or rationality, and so this article is only tangentially related to my discussion earlier – unless we make use of cultural beliefs about the impact of emotion on rationality (‘you can’t think straight, you’re too emotional’. Or ‘you can think logically, you don’t let your emotions get in the way’), which are themselves to blame for the common judgment that women’s rationality is inferior to that of men. But either way, it might add something to the overall discussion… it suggests, in any case, that there might be some biological grounding for our culturally created differences in behavior.