A prospective study of inter-episode consistency of manic and mixed subtypes of bipolar disorder

Background: Few studies have compared symptom presentations across manic or mixed episodes in manic-depressive patients. Methods: In the current study we report on symptom presentations of 68 prospectively-evaluated subjects diagnosed with Bipolar Disorder during two discrete manic or mixed episodes. Each episode was categorized using DSM-IIIR criteria for Bipolar Disorder, manic or mixed, as well as a less restrictive definition for manic and mixed states derived from receiver operating characteristic (ROC) analysis of symptoms. Results: The occurrence of mixed bipolar episodes was not random using either the DSM-IIIR or ROC-derived definitions of mixed episodes. Limitations: Subjects were not all fully medication-free at the time of evaluation which may have altered symptom presentation. The total duration of the study was limited, with the longest inter-episode interval under 6 years. Conclusions: Although there was variability in mixed symptomatology between episodes, the occurrence of mixed episodes was not random. Manic and mixed episodes tend to recur true to type.