Agitated depression: unipolar? Bipolar? Or both?

The classification of agitated depression (major depressive episode (MDE) plus psychomotor agitation) in mood disorders is unclear. DSM-IV is neutral on this point. As antidepressants may increase agitation, a better understanding of agitated depression is important for clinical practice. Study aim was to find if agitated depression was closer to bipolar or to unipolar disorders, by studying its association with variables typically related to bipolar disorders (early onset, many recurrences, more atypical features, more bipolar family history), and by studying its association with bipolar II disorder. Consecutive 151 unipolar and 226 bipolar II psychoactive drug-free MDE outpatients were interviewed with the Structured Clinical Interview for DSM-IV, when presenting for MDE treatment. Agitated MDE patients were compared with nonagitated MDE patients. Statistics were t test for means, two-sample test of proportion, and logistic regression (STATA 7). Agitated MDE was present in 85 patients (22.5%). It had significantly more bipolar II disorder patients (80.0% vs. 54.1%, p = 0.0000), more females, lower age at onset, longer duration of illness, more MDE recurrences, more atypical features, more MDE symptoms, and more family history of bipolar disorders, than nonagitated MDE. To control for the possible confounding effect of bipolar II disorder, logistic regression was used. All the significant differences became nonsignificant. Results might suggest that agitated MDE might be closer to the bipolar spectrum than to unipolar disorder, because it was associated with variables typically distinguishing bipolar from unipolar disorders, and with bipolar II disorder. Further studies on this topic are needed.