Objective: We assessed the spectrum and severity of bipolar symptoms that differentiated bipolar disorder (BD) clinical states, employing the Bipolar Inventory of Symptoms Scale (BISS) which provides a broader item range of traditional depression and mania rating scales. We addressed symptoms differentiating mixed states from depression or mania/hypomania.
Method: One hundred and sixteen subjects who met DSM-IV-TR criteria for BD and were currently in a depressed, manic/hypomanic, mixed episode, or recovered state were interviewed using the BISS.
Results: A subset of manic items differed between mixed episodes and mania/hypomania or depression. Most anxiety items were more severe in mixed subjects. BISS Depression and Manic subscales differentiated episodes from recovered status. The majority of depression and manic symptoms differentiated mood states in the predicted direction. Mixed episodes had overall greater mood severity than manic/hypomanic episodes or depressed episodes.
Conclusion: These results indicate that a small subset of symptoms, several of which are absent in DSM-IV-TR criteria and traditional rating scales for bipolar studies, aid in distinguishing mixed episodes from depressive or manic/hypomanic episodes. The results also support the utility of a comprehensive BD symptom scale in distinguishing primary clinical states of BD.