Background: Mixed-states of bipolar disorders (BPD) may predict worse future illness and more depressive than manic morbidity, challenging a tendency to conflate mixed-states and mania.
Methods: Patients (N=247) were followed-up systematically for 24 months following hospitalization for initial major episodes of DSM-IV type-I BPD and scored for weekly interval morbidity-types.
Results: Overall morbidity during follow-up was 1.6-times greater following mixed (n=97) versus manic (n=150) first-episodes of BPD (60.0 vs. 37.8%-of-weeks; p<0.0001). Patients with initial mixed-states had a nearly 12-fold later excess of mixed-states, 6.5-times more major depression, and 69% more dysthymia during follow-up than those presenting in mania. In contrast, manic first-episodes were followed by over 10-times more mania, 6-times more hypomania, and 35% more psychotic illness.
Limitations: Estimates of longitudinal morbidity may be inaccurate, and ongoing treatment may distort them.
Conclusions: Based on detailed, prospective assessments among first-episode BPD patients, those presenting in mixed-states were more ill, and much more likely to experience mixed, depressive and dysthymic morbidity during follow-up, versus much more mania, hypomania, and perhaps more psychosis following mania. The findings support two markedly dissimilar subtypes of BPD, and call for more explicit therapeutic studies of mixed-states.
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