Bipolar spectrum disorder: differential diagnosis and treatment.

Bipolar disorder commonly presents as a recurrent mood disorder characterized by frequent depressive episodes. Although manic or hypomanic phases are required for the diagnosis to be made based on current diagnostic criteria, a wider expression of mood instability and other historical features or family history may suggest the presence of a bipolar spectrum illness. This article covers the diagnostic issues related to bipolar disorder and the spectrum concept of the illness. A new definition of bipolar spectrum disorder is suggested, and treatment principles and options are discussed. Primary care providers often encounter patients who have depression and mood problems, placing them in a key position for the diagnosis and treatment of this psychiatric illness.