The Emergence of the Bipolar Spectrum: Validation along Clinical-Epidemiologic and Familial-Genetic Lines

A new paradigm of the bipolar spectrum is shaping up in the research literature and in clinical practice. It represents a partial return to the Kraepelinian broad concept of manic depression which included many recurrent depressions. Although bipolar I and bipolar II are now part of the official nomenclature of Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition (DSM-IV), the breadth of bipolarity is not represented in this manual. Old and new evidence indicate that the most common form of bipolar II is characterized by hypomanias of shorter duration than the arbitrary threshold of four days, and that cyclothymic depressions represent a prevalent variant of the bipolar II pattern.…