Objective: To report the frequency of intra-episode manic symptoms in depressive episodes, and to evaluate unipolar depressive mixed state (DMS) as bipolar spectrum.
Method: A total of 958 (863 unipolar, 25 bipolar II, and 70 bipolar I) depressive in-patients were assessed in terms of manic symptoms at admission, and several clinical variables using standardized methods.
Results: The frequency of manic symptoms (flight of idea, logorrhea, aggression, excessive social contact, increased drive, irritability, racing thoughts, and distractibility) was significantly higher in bipolar depressives than in unipolar depressives. Unipolar depressives with DMS – defined as having two or more manic symptoms – had more similarities to bipolar depressives than to other unipolar depressives in clinical variables such as onset age, family history of bipolar disorder, and possibly suicidality.
Conclusion: Depressive mixed state is frequent, particular in bipolar depressives. Unipolar depressives with DMS may be better classified into bipolar spectrum.