ABSTRACT
The affect disorders comprise those illnesses in which mood disturbance is the leading feature, taking the form either of a depression or an elation or both. The fact that many of these patients experience recurrent episodes of both elation and depression led Kraepelin in 1896 to formulate the concept of manic-depressive psychosis. In other words, the elations and depressions are opposite phases of one disease. Depressive illnesses may occur without elations, and vice versa, and the individual may experience a single attack or multiple attacks of either phase, or of both phases.
