On Mental Disorders, Part One

One of the major errors that people make when thinking of DSM mental disorders and the like is to think of them as diseases. While this is undoubtedly true for some diagnoses in the DSM, the fact of the matter is that "mental disorder" and "disease" are really very different concepts.

While disease categories are abstractions based on etiology, mental disorders... well, aren't. That isn't even the ideal anymore.

As I discussed in an earlier post, certain conditions must be met for something to be called a disease:

• It must be an impairment of the normal state of the living animal or plant body or one of its parts.
• It must interrupt or modify the performance of the organism's vital functions.
• It must be typically manifested by distinguishing signs and symptoms.
• It must have a distinguishing etiology (which may be simple or complex).
  

The conditions for something being called a mental disorder, however, are very different. Unlike with the concept of "disease", however, these are anything but straightforward.

Going to MedLine Plus, for instance, yields the following definition: "a mental or bodily condition marked primarily by sufficient disorganization of personality, mind, and emotions to seriously impair the normal psychological functioning of the individual—called also mental illness."

In other words, while a disease is an abstraction based on etiology, a mental disorder is an abstraction based on symptoms. While a disease is a process which causes its symptoms, a mental disorder is a label which describes them or a description of them. Classification of mental disorders makes no reference to the why, only to the what. They have no explanatory value whatsoever; to say that a psychiatric diagnosis has any explanatory value whatsoever is to commit nominal fallacy.

Even this, however, isn't really satisfying. What, for instance, does "disorganization" mean? How do you decide whether or not something "impair[s] the normal psychological functioning of the individual"? Heck, just what does "normal psychological functioning" mean?

These questions are important because of the "wiggle room" built into these terms. In the DSM-I and II, for instance, homosexuality was considered a mental disorder -- homosexuals were considered "broken" heterosexuals whose attraction to members of their own sex represented an impairment to their functioning qua members of their gender. Another infamous example of this problem featured a doctor who pathologized the desire of slaves to flee their masters (he considered whipping to be curative).

My abnormal psychology textbook provides a somewhat more clear answer: it defines one as "a psychological dysfunction within an individual that is associated with distress or impairment in functioning and a response that is not typical or culturally expected." (p. 2)

This, in turn, breaks down into four parts. To qualify as a mental disorder, a set of symptoms must:

• Constitute a "psychological dysfunction".
• Be within the individual.
• Be associated with distress and/or impairment in functioning.
• Be associated with (at least one) response that is not typical or culturally expected.

Unfortunately, none of these is quite what it seems. I'll write more on this later, but for now... just keep in mind: a mental disorder is not a disease.

Edit: Corrected an embarassing typo.