Bipolar disorder: "pure" versus mixed depression over a 1-year follow-up.

OBJECTIVES: To compare two samples of Bipolar (BD) patients presenting "pure" (D) and mixed (Mx) depression to assess any difference in terms of clinical outcome, social functioning and quality of life during a 1-year follow-up. METHODS: A total of 114 depressed outpatients (HDRS > 13) were included. "Pure" depressed (D, n = 76) were divided from "mixed" depressed (Mx, n = 38) by the number of concomitant manic symptoms. All patients were evaluated by the Hamilton Depression Rating Scale (HDRS), the Hamilton Anxiety Rating Scale (HARS), the Young Mania Rating Scale (YMRS), the Global Assessment of Functioning (GAF), the Social Adjustment Self-reported Scale (SASS) and the Quality of Life Scale (QoL), at baseline and after 1, 3, 6 and 12 months of treatment. RESULTS: Mx patients were significantly younger at the onset of BD. Manic features persisted significantly higher in Mx than in D patients all over the follow-up period. Axis I comorbidities had a negative impact on the course of social functioning over the medium term period, while Mx patients showed a faster improvement in social adjustment than "pure" depressed patients. CONCLUSIONS: Mixed features may persist relatively stable throughout a depressive episode, having a negative impact over clinical and functional outcome, but not on social adjustment.