Factors associated with the course of symptoms in bipolar disorder during a 1-year follow-up: depression vs. sub-threshold mixed state

BACKGROUND: Mixed mood states, even in their sub-threshold forms, may significantly affect the course and outcome of bipolar disorder (BD). AIM: To compare two samples of BD patients presenting a major depressive episode and a sub-threshold mixed state in terms of global functioning, clinical outcome, social adjustment and quality of life during a 1-year follow-up. METHODS: The sample was composed by 90 subjects (Group 1, D) clinically diagnosed with a major depressive episode and 41 patients (Group 2, Mx) for a sub-threshold mixed state. All patients were administered with a pharmacological treatment and evaluated for depressive, anxious and manic symptoms by common rating scales. Further evaluations included a global assessment of severity and functioning, social adjustment and quality of life. All evaluations were performed at baseline and after 1, 3, 6 and 12 months of treatment. RESULTS: The two groups were no different for baseline as well as improvement in global severity and functioning. Though clearly different for symptoms severity, the amount of change of depressive and anxiety symptoms was also no different. Manic symptoms showed instead a trend to persist over time in group 2, whereas a slight increase of manic symptoms was observed in group 1, especially after 6 months of treatment. Moreover, in group 1, some manic symptoms were also detected at the Young Mania Rating Scale (n = 24, 26.6%). Finally, improvement in quality of life and social adjustment was similar in the two groups, though a small trend toward a faster improvement in social adjustment in group 1. CONCLUSIONS: Sub-threshold mixed states have a substantial impact on global functioning, social adjustment and subjective well-being, similarly to that of acute phases, or at least major depression. In particular, mixed features, even in their sub-threshold forms, tend to be persistent over time. Finally, manic symptoms may be still often underestimated in depressive episodes, even in patients for BD.