Clinical prediction of response to lithium prophylaxis in bipolar patients: the importance of the previous pattern of course of the illness.

The response to lithium prophylaxis was evaluated in a sample of bipolar patients subdivided into groups, according to the previous pattern of course for their illness: MDI (sequence mania-depression-free interval), DMI (sequence depression-mania-free interval), CC-LC (continuous circular course with long cycles), CC-RC (continuous circular course with rapid cycles), IRR (irregular course). The percentage of responders to treatment was significantly different among the five groups, and the difference could be ascribed mainly to the high response rate in the MDI group and the low response rate in the DMI and CC-RC groups. These data suggest that the classification of bipolar patients on the basis of the previous pattern of their course of illness may be useful for predicting lithium response.