VALIDITY OF RAPID-CYCLING AS A COURSE SPECIFIER FOR BIPOLAR DISORDER

Objective: This study's aim was to test the validity of rapid cycling, defined by criteria consistent with those proposed in the DSM-IV draf t, as a course specifier for bipolar disorder. Method: The study was c onducted at a university center for affective disorders on patients fu lfilling Research Diagnostic Criteria for bipolar disorder. Thirty-sev en rapid-cycling patients, i.e., patients with at feast four affective episodes during the previous year, were compared with 74 nonrapid-cyc ling patients on several demographic and clinical variables. All patie nts were then followed up prospectively for 2-5 years by monthly perso nal interviews. Results: The rapid-cycling group was significantly old er and had a significantly longer illness duration than the nonrapid-c ycling group but did not have a significantly higher percentage of wom en or frequency of current hypothyroidism. During each year of follow- up, the mean number of affective episodes and the percentage of patien ts with at least four affective episodes were significantly higher amo ng rapid-cycling patients. Rapid-cycling patients with a pole-switchin g pattern during the year preceding intake were significantly more lik ely than other rapid-cycling patients to have at least four affective episodes during each of the first 4 years of follow-up. Conclusions: T hese findings support the practical usefulness of rapid cycling as a c ourse modifier for bipolar disorder, since it identifies a patient sub group with a high recurrence rate. The predictive value of the modifie r may be enhanced by the requirement of a pole-switching pattern. Sinc e no external (i.e., unrelated to course) validator was found, the ide a that rapid cycling represents one extreme of a continuum of episode frequency in bipolar disorder remains viable.