Three times more days depressed than manic or hypomanic in both bipolar I and bipolar II disorder.

OBJECTIVES

To assess the proportion of time spent in mania, depression and euthymia in a large cohort of bipolar subjects studied longitudinally, and to investigate depression/mania ratios in patients with bipolar I versus bipolar II disorder.

METHODS

Clinician-adjusted self-ratings of mood were completed daily for one year for naturalistically treated outpatients with bipolar I (n = 405) or bipolar II (n = 102) disorder. Ratings were analyzed for mean time spent euthymic, depressed, manic, hypomanic, and cycling, and the percentages of time spent ill were compared between the two groups.

RESULTS

Percentages of time spent ill for bipolar I versus II patients were: euthymia 47.7% versus 50.2%; depression 36.0% versus 37.0%; hypomania 11.5% versus 9.8%; mania 1.0% versus 0.2%; and cycling 3.7% versus 2.8%. The depression/mania ratio was 2.9 in the bipolar I and 3.8 in bipolar II sub-groups.

CONCLUSIONS

Depression represents the predominant abnormal mood state for treated outpatients with bipolar I and II disorder. In contrast to other studies, we found that depression/mania ratios were of a similar magnitude, suggesting the same tendency towards mood instability in both sub-groups.