ABSTRACT
Major depressive disorder (MDD) is a recurrent, disabling, and potentially lethal illness with high rates of residual symptoms and persistent psychosocial impairments even among a large percentage of individuals who respond to acute phase therapy. The point prevalence of chronic and recurrent cases of major affective disorder exceeds that for acute, first-episode disorders [1,2]. In the 1970s, Angst and associates [3] and Zis and Goodwin [4] documented the likelihood of relapse and recurrence in the major affective disorders. These findings were prospectively confirmed in a series of studies conducted under the auspices of the National Institute of Mental Health (NIMH) Collaborative Study on the Psychobiology of Depression as summarized by Keller andHanks [5]. At the least, 50%of thosewho have experienced one episode of major depression will experience another at some later point. Thus, assuming a lifetime risk formajor depression of 5% [6], an individual who has recovered
from an initial episode of depression has at least a 10-fold greater risk of having another episode when compared to a person of similar age and sexwho has never been clinically depressed. For recurrent (unipolar)major depression and bipolar depression, where recurrence rates of at least 70-90% are expected, the increase in risk for recurrence is 14-to 18-fold when compared with that in the general population [3,5,7-9]. Chronic minor depressions (i.e., dysthymia) have a similarly marked increase in the risk of subsequent major depressive episodes [5].
