What Should Count as a Mental Disorder
in DSM-V?

If sick men fared just as well eating and drinking and living exactly as healthy men do . . . there would be little need for the science [of medicine].

attributed to Hippocrates

Well, while I’m here, I’ll do the work—and what’s the work? To ease the pain of living. . . .
Allen Ginsberg

What exactly is a “mental disorder”? For that matter, what criteria should determine whether any condition is a “disease” or a “disorder”? Is “disease” something like an oak tree—a physical object you can bump into or put your arms around? Or are terms like “disease” and “disorder” merely abstract, value-laden constructs, akin to “injustice” and “immorality”? Are categories of disease and disorder fundamentally different in psychiatry than in other medical specialties? And—by the way—how do the terms “disease,” “disorder,” “syndrome,” “malady,” “sickness,” and “illness” differ?

Anyone who believes there are easy or certain answers to these questions is either in touch with the Divine Mind, or out of touch with reality. To appreciate the complexity and ambiguity in this conceptual arena, consider this quote from the venerable Oxford Textbook of Philosophy and Psychiatry: 

"The term 'mental illness' is probably best used for those disorders that are intuitively most like bodily illness (or disease) and, yet, mental rather than bodily. This of course implies everything that is built into the mind-brain problem!"^1(p11)

In a single sentence, we are already grappling with the terms “illness,” “disorder,” and “disease,” not to mention Cartesian psychology! And yet—daunting though these issues are—they are central to the practical task now before the DSM-V committees: figuring out what conditions ought to be included as psychiatric disorders.

To prefigure one element of my own position, I again quote from the Oxford Textbook’s chapter 20, “Values in Psychiatric Diagnosis”:

"Our conclusion . . . [is] that the traditional medical model, and the claim to value-free diagnosis on which it rests, is unsupportable; and that, to the contrary, diagnosis, although properly grounded on facts, is also, and essentially, grounded on values. . . . [This] is consistent with late twentieth century work in the philosophy of science . . . showing the extent to which the scientific process, from observation and classification to explanation and theory construction, does not depend on merely passively recording data, but is instead actively shaped in complex judgments. . . ."^1(p565)

The Oxford authors wisely observe that “adding values” does not entail “subtracting facts.” Thus, when we assert that someone with paraplegia has a pathological (from the Greek pathos, “suffering”) condition, we are making a claim grounded in a certain kind of value judgment; namely, that the inability to move one’s legs is in some sense “not a good thing.” In a society that greatly valued paralysis and devalued walking, paraplegia would not constitute “pathology.” On the other hand, we also “add facts” in reaching the conclusion that Mr Jones—who cannot move his legs—has suffered a fracture-dislocation of the lumbar vertebrae. In short, medical diagnosis is a matter of “facts plus values.”¹ (Incidentally, we do not escape this evaluative dimension by appealing to some putative “evolutionary standard” based on notions of how we humans were “designed.”² As clinicians, we must still make value judgments as to what degrees of departure from supposed evolutionarily designed responses should—or should not—count as “disease”).

Similarly, when psychiatrists adduce evidence of suffering and incapacity in diagnosing a psychiatric disorder, we implicitly invoke certain broad values; for example, that it is generally “not a good thing” when a human being is unable to eat, sleep, think, and work. At the same time, we “add facts”: we note that the patient has lost 20 lb in the last month; that she gets only 3 hours of sleep each night; that she cannot subtract serial 7s accurately; and perhaps, in some cases, that she shows marked elevation of her serum cortisol level.³ That the facts we adduce as psychiatrists often differ from the kind cited by, say, orthopedists, does not render our data less “factual”! Indeed, some of the most important facts about the suffering and incapacitated psychiatric patient are facts intrinsic to the person’s experience—the phenomenology or “life world” of the patient.^4-6 Thus, when the depressed patient tells us, “I feel like I’m being suffocated by my depression” and “I feel like an empty shell about to be crushed,” we justifiably regard these as facts of the patient’s felt experience.

The notion that only conditions associated with anatomical lesions or abnormal physiology count as “real” diseases—the “lumps and labs” model of disease⁷—denigrates the phenomenological realm. Sadly, such misplaced positivism—based on a crude understanding of pathologist Rudolph Virchow’s views—has been used to whack psychiatry over the head for nearly 50 years.^8,9 That said, in the model I shall develop, the search for abnormal neuroanatomy, physiology, and biomarkers does play an important role in the later stages of disease classification.

Mental disorders: essential definitions
Deciding what should “count” as a mental disorder is not the same as offering an essential definition of “mental disorder.” An essential definition is one that specifies necessary and sufficient conditions; for example, “a closed figure consisting of 3 line segments linked end-to-end” constitutes the nec­essary and sufficient conditions for ascribing the term “triangle.”

The philosopher Ludwig Wittgenstein (1889-1951) taught us that—with the possible exception of mathematical terms—commonly used words do not have essential definitions.^10,11 For example, it is almost impossible to specify the necessary and sufficient conditions that define the term “game.” On the other hand, Wittgenstein argued, we can identify certain “resemblances” among members of a particular “family.” These family resemblances—blond hair, blue eyes, for example—help us to recognize the family, even though no single feature is present in every family member.