The clinical features of bipolar depression: a comparison with matched major depressive disorder patients.

BACKGROUND: Despite a resurgence of interest in the treatment of bipolar depression, there have been few controlled studies of the clinical characteristics of this condition. Identification of any distinctive clinical "signatures" of bipolar depression would be helpful in determining treatment options in the clinical setting.
METHOD: From a cohort of 270 inpatients and outpatients assessed in detail during a DSM-IV major depressive episode, 39 bipolar I disorder patients were identified and closely matched with 39 major depressive disorder patients for gender, age, and the presence or absence of DSM-IV melancholic subtype. Patients were compared on a broad range of parameters including the Hamilton Rating Scale for Depression (depression severity), 54 depressive symptoms, the Newcastle Endogenous Depression Diagnostic Index, 3 family history items, 2 physical health items, the CORE scale (psychomotor disturbance), and 5 history items.
RESULTS: Although the bipolar patients were no more severely depressed than the major depressive disorder controls, they were more likely to demonstrate psychomotor-retarded melancholic and atypical depressive features and to have had previous episodes of psychotic depression. These findings were largely duplicated even when the population was confined to those with DSM-IV melancholia.
CONCLUSION: The clinical admixture of psychomotor-retarded melancholic signs and symptoms, "atypical" features, and (less frequently) psychosis may provide a "bipolar signature" in clinical scenarios when there is uncertainty concerning the polarity of a depressive presentation.