Okay, I'll try to keep it short this time. (Whoops! I think I'm going to fail.) The so-called "mental disorders" are catalogued in a scriptural document called the Diagnostic and Statistical manual of Mental Disorders, Fourth Edition, Text Revision, or DSM-IV-TR, produced by the American Psychiatric Association. For those not familiar with it, the DSM is close to being a cube of paper -- nearly 1,000 pages. Most of it consists of sections headed by the name of an official mental disorder, with a code number-- e.g., 297.1 Delusional Disorder -- followed by a text description with sub-headings "Diagnostic Features," "Subtypes," "Associated Features and Disorders," "Specific Culture and Gender Features," "Prevalence," "Course," and "Differential Diagnosis." The sections conclude with a list of "Diagnostic criteria." In many cases, not all critieria need be present; in some cases, you need to take at least some number from one list and some other number from another, like a Chinese menu (2 from column a, 3 from column b).
A curious feature of the DSM is that clinicians are to record their diagnoses in 4 so-called "axes." Axis 1 constitutes most of the recognized mental disorders -- everything from Attention-Deficit and Disruptive Behavior Disorders, to Female Orgasmic Disorder, to Sleepwalking Disorder, to Pyromania, to Psychotic Disorder Not Otherwise Specified. Axis 2 constitutes the so-called "personality disorders" -- e.g. Antisocial Personality Disorder, Borderline Personality Disorder, Histrionic Personality Disorder -- and, for reasons which are not very convincingly explained, Mental Retardation. Axis III is what APA calls "General Medical Conditions," that is diseases that doctors who aren't psychiatrists are supposed to deal with, but which should be in the psychiatric record because they are relevant. Axis IV consists of psychosocial and environmental problems -- e.g., you're out of work, your kids hate you, you're wife is having sex with your brother. There is also an Axis V which doesn't consist of specific diseases or problems but is just an overall score, which ranges from 100 (The Buddha: "Superior functioning in a wide range of activities, life's problems never seem to get out of hand, is sought out by others because of his or her many positive qualities.") through the 40s (Uncle Phil who we aren't supposed to talk about: "Serious symptoms [e.g., suicidal ideation, severe obsessional rituals, frequent shoplifting) or any serious impairment in social, occupational, or school functioning (e.g., no friends, unable to keep a job].) to the single digits (President of the United States: "Persistent danger of severely hurting self or others (e.g., recurrent violence) or persistent inability to maintain minimal personal hygiene or serious suicidal act with clear expectation of death.")
An important feature of the DSM-IV is that, as they proudly proclaim in the introduction, they assiduously avoid any mention of etiology -- that is, the underlying causes and processes of disease. All of the "mental disorders" are, by definition, what are called syndromes -- conditions defined solely as bundles of symptoms. Doctors in general are uncomfortable with syndromes that don't have an underlying, known etiology. They often argue about whether such conditions really are "diseases" at all. Once a syndrome is found to have more than one underlying cause, it splits into more than one disease. For example, diabetes -- originally defined by a symptom, excess sugar in the blood -- is now divided into two major diseases, called Type 1 and Type 2, and some minor ones (e.g., gestational diabetes). Type 1 is an autoimmune disorder in which the immune system destroys the insulin-producing cells of the pancreas, and Type 2 is a metabolic disorder caused by obesity, excessive consumption of carbohydrates, and physical inactivity interacting with genetic predisposition. When etiology is understood, doctors are much happier because a) they can usually make a confident diagnosis through a physical finding that the disease process is present, e..g the pancreas is not producing insulin, or a pathogen can be harvested from the blood and grown in culture; and b) they can use treatments with a known method of action and clear criteria for success, e.g. the pathogen is gone.
In psychiatry, however, that can't happen, or at least it doesn't. As I have said before, once the specific etiology of a mental disorder becomes known, the disorder begins to slip away from psychiatry toward neurology or some other specialty. In the psychiatric disorders, there are etiological theories, but seldom any consensus. (The DSM-IV does retain some disorders of known or at least partly understood etiology, such as vascular and HIV-related dementia, but these are not really considered psychiatric conditions and aren't normally treated by psychiatrists.) The etiological agnosticism of DSM diagnoses contributes to a significant philosophical problem: how do we decide that any of these entities are "diseases" in the first place? And I mean that in several senses.
- Is each of them really a single entity? Is "oppositional defiant disorder" a real "thing," like gout, or is it just a label, a fancy way of saying, "that kid is a pain in the ass"?
- Is there necessarily something "wrong" with the person at all? Who decides? Is your person with "hystrionic personality disorder" maybe just a drama queen, who I am free to find entertaining if a bit over the top?
- If we agree that there is something wrong here, and looks like most of the people who fit the diagnostic criteria have more or less the same wrong thing going on, is it a medical problem? Why is it a disease and not, say, a moral failing, or a skill or talent deficit?
Next: There are pills that make you large, and there are pills that make you small . . .