The relative prophylactic efficacy of lithium against manic and depressive recurrences in bipolar patients.

The relative prophylactic efficacy of lithium against manic and depressive recurrences was examined in 61 patients (22 males, 39 females) with bipolar manic-depressive disorders by comparing the number of manic and depressive episodes for each patient during equally long periods before and during lithium treatment. In all the patients, the percentage of depressive episodes during lithium was smaller than that of manic episodes. The better antidepressive than antimanic prophylactic effect of lithium was significant only in male patients, while the reduction of manic episodes during lithium was greater in females. The fraction of patients without depressive episodes on lithium was greater in the male group. The results obtained with this study design indicate that lithium is an effective antidepressive prophylactic agent in bipolar patients. Sex differences are also implicated in response to lithium prophylaxis.