Introduction: Rapid cycling (RC) in bipolar disorders is widely believed to predict future morbidity and poor treatment response, although empirical testing of its predictive utility remains limited.
Methods: In 360 DSM-IV bipolar I (N=218) and II (N=142) disorder subjects (64% women) followed over an average of 13.3 years, we evaluated factors associated with RC status with bivariate and multivariate techniques, and response to lithium maintenance treatment (recurrence rates, time ill, survival analysis of time to recurrence on lithium).
Results: RC risk (15.6% of cases) was 5. 1-times greater in bipolar II vs. I subjects (30.3%/6.0%), in minor excess in women vs. men (17.9%/11.5%), and associated with premorbid cyclothymia, depressive first episodes, older onset age, and being employed or married. Before lithium, RC vs. non-RC cases had more mean total (3.9/1.2), manic, and depressive episodes/year, and greater percent time ill (60%/38%). During treatment, prior RC status was unrelated to time to first recurrence and other measures of morbidity and improvement including percent time ill, although depressive episodes were 2.7-times more frequent, and there was 13.7% less chance of full protection from all recurrences in RC cases.
Limitations: The study is naturalistic, without random assignment or blind assessment.
Conclusions: The RC bipolar subtype was strongly associated with type II diagnosis, higher average prelithium episode frequency and percent time ill, and weakly with female sex, but not with greater overall morbidity during treatment.