OK. This is the exam. You’d better do well.
One. This is the answer of the Diagnostic and Statistical Manual of the American Psychiatric Association (DSM): Major depression. DSM-3 created major depression in 1980, and the term lumps together the previous two separate depressions (see below). Major depression is really quite a heterogeneous category, and you qualify for it whether you have a pistol in your mouth or you can’t remember your children’s birthdays (”diminished ability to think).” Now, there are several other depressive categories in the new DSM-5, that just came out two months ago, but they’re situational: you’re having your period, you’ve taken bad Mexican meds, or you’re chronically depressed (“dysthymia”).
Oh, and there is this doozy, designed for ill-behaved children who kick the furniture: “disruptive mood regulation disorder,” which we used to call “pediatric bipolar disorder” until overuse made it a professional embarrassment.
But yeah, on the basis of psychopathology, or the symptoms you actually have, there’s only one depression: major depression.
Two. Melancholic depression + non-melancholic depression. This is a distinction that Australian psychiatrist Gordon Parker re-activated in his 1996 book, Melancholia: A Disorter of Movement and mood (Cambridge, 1996); but in fact psychiatry has always recognized two depressions, as distinct as mumps and tuberculosis (until, that is, DSM-3 in 1980). Melancholic depression is one of the oldest diseases in medicine, going back to the Ancients. And its diagnosis is quite straightforward: deep sadness, complete absence of joy or hope, and changed speed of thought, speed of movement: either an agitated, anxious picture with lots of pacing about and muttering “I’m lost”; or a stuporous decline into staring at the wall for hours on end.
Non-melancholia, by contrast, used to be called “nervous illness,” or, more recently, “mixed anxiety-depression,” and these patients are not necessarily sad. But they’re demoralized, discouraged, anxious, have tons of bodily symptoms, are terribly fatigued, and tend to obsess about the whole package.
How do we know that these are separate depressions, and not just degrees on a gradient? Because there is a biological marker for melancholia called the dexamethasone depression test; and because melancholia responds well to a class of meds called “tricyclic antidepressants,” introduced in the US in 1959 with Tofranil (imipramine). Older clinicians will still remember Tofranil; it hasn’t lost its effectiveness. Nobody else has ever heard of it. Melancholia also responds beautifully to electroconvulsive therapy (ECT), which works so well (80-percent-plus effectiveness) that it’s now making a big comeback (Taylor & Fink, Melancholia: The Diagnosis, Pathophysiology and Treatment of Depressive Illness, 2006). Non-melancholia does not respond beautifully (though it may respond somewhat) to either treatment.
Three. Melancholia, non-melancholia, and “atypical depression.” Atypical was described by English psychiatrist William Sargant in 1959 and offers a kind of paradoxical picture: over-sleeping (as opposed to insomnia), over-eating (as opposed to food refusal), great sensitivity to the environment (such as being dumped romantically), as opposed to the indifference to the environment of melancholia. Sargant said it responded to a class of medications called the monoamine oxidase inhibitors (MAOIs). (Shorter, Historical Dictionary of Psychiatry, Oxford 2005) The term has recently been revived by New York psychiatrist Donald Klein.
Four and more. The above three, plus depression classified on the basis of cause: post-stroke depression, post-psychosis depression, the depression of Parkinson’s, the depression of alcoholism, and so forth. Bringing in “cause,” or better put, circumstance, opens the door to a very large number of depressions, all of which would have more or less the same psychopathology as in number two.
And, ummmh, I’ve cheated a bit, because the major-depression crowd actually do accept a second depression -- but few serious observers believe in it – and it’s the depression of bipolar disorder. The argument here is that bipolar disorder is such a special ailment that its depression must be different. DSM-5 does not make this argument; its bipolar depression is the same as its unipolar depression, namely, major depression. But some drug companies have succeeded in getting “the depression of bipolar disorder” acknowledged as separate, and the leading textbook on bipolar disorder, Fred Goodwin and Kay Jamison’s Manic-Depressive Illness: Bipolar Disorders and Recurrent Depression (Oxford, 2007), now in its second edition, thinks that they’re different. Yet for a number of other authorities it makes no sense to classify depression on the basis of polarity, and the leading psychopathologist in the U.S. Michael Alan Taylor at the University of Michigan, thinks that the depression of bipolar disorder is plain old melancholia. (Taylor & Vaidya, Descriptive Psychopathology, Cambridge, 2009).
That’s it. I hope you passed.