ABSTRACT
Modern psychiatric nosology, and the classification of mood disorders, did not really take shape until the early twentieth century with the work of Emil Kraepelin. Kraepelin was one of the pioneers in differentiating psychiatric conditions. However, he combined most forms of mood disorder, including unipolar and bipolar depression, into the large category of manic-depressive insanity (1). It wasn’t until the late 1950s and 1960s that unipolar and bipolar depression were separated into unique diagnostic syndromes [see Akiskal (2) for review]. The key element that separates bipolar disorder (BD) and its subtypes from unipolar disorder is the occurrence of mania or hypomania. Over the last three decades there have been varying suggestions of how to subdivide BD (2). In this chapter, we focus on what we feel are the most well-established subgroups within and separate from BD type I, namely, BD type II, cyclothymic disorder, rapid cycling, and psychotic mania. Type II BD and cyclothymia are specific diagnoses in the DSM-IV (3), while rapid cycling and psychotic mania are DSM-IV specifiers that can be applied to either type I or II BDs (Table 1).
