ABSTRACT
The DSM-IV and the International Classification of Diseases, 10th revision (ICD-10), provide clear diagnostic criteria for distinguishing bipolar disorder from unipolar disorder. The clinical signs and symptoms of unipolar disorder include loss of interest or pleasure, reduced energy, poor sleep, decreased appetite and weight loss, hopelessness or worthless feeling, and suicidal thoughts. Whereas bipolar disorder includes all of the clinical symptoms of major depression during a depressive episode, it also obviously is characterized by a number of symptoms during the manic phase including an elevated, expansive, or irritable mood as well as grandiosity, decreased sleep and appetite, pressured speech, racing thoughts, and excessive involvement in pleasurable but potentially dangerous activities. Moreover, manic and depressive symptoms often occur together in the so-called mixed state. Although clinicians and investigators concur that these two syndromes are surely distinct entities, in terms of both clinical course and response to treatment, it is not clear what the definitive neurobiological distinctions are between these two disorders. During the last decade, extraordinary advances in both neuroscience and psychopharmacology have provided the field with the tools to further understand the differences between these mood disorders.
