SUPPLEMENT Depression The Nosology of Depression: The Endogenous-Reactive Concept

Controversies surrounding the distinctions between endogenous and reactive types have characterized the literature on depression. Reviewing seven pertinent factor analytic studies, these authors found sufficient con-sensus to support the independence of the endogenous and reactive factors. It is sug-gested, however, that these factors may not represent two etiologically distinct types of depression. The endogenous factor may re-flect a “classical ” depressive syndrome, whereas the reactive factor may reflect a psychiatric disorder in which depression is only one symptom “contaminated ” by other nondepressive clinical features. W E DO NOT know what causes depres-sion, how to objectively define its presence, how to classify the various types of depression and whether the differences between them are quantitative or qualita-tive (if indeed there are separate types), or often, how to select the most appropriate treatment for a particular depressed patient. The problems are compounded by the multiple use of the term “depression”-to describe a mood, a symptom, a syndrome, and a specific disease entity. Furthermore