ABSTRACT
Differentiating among affective disorders is a complex matter because subtle clinical features and the overlap among various conditions frequently complicate diagnosis. Thus, for example, depression may occur as a full syndrome (major depressive disorder) but it occurs just as frequently in attenuated or subsyndromal forms. Moreover, depressive disorders may be episodic or chronic, and even episodic forms may resolve to chronic states such as a phenomenon known as “double depression” (Keller & Shapiro, 1982) in which a major depressive episode is superimposed on a low-grade but chronic depression rather than reaching full remission. The relationship between dysthymia and depressive (melancholic) temperament or personality remains unclear, particularly whether these represent distinct disorders or variants of major depression. Finally, differentiating between unipolar and bipolar depression can be quite complicated, particularly when hypomanic states or hyperthymic temperament form part of the clinical presentation.
