A comparison of the clinical characteristics of the depressive state was made between 25 patients with a diagnosis of depressive psychosis (unipolar) and 25 patients with a diagnosis of manic-depressive psychosis (bipolar). Patients were observed for a 14-day drug-free period in a research ward during which time mania was absent. Higher levels of physical activity, overt expression of anger, and somatic complaints differentiated the depression of the unipolar patients from those of the bipolar patients who tended to be less active and more socially withdrawn. Anxiety and psychotic behavior were not differentiating characteristics, although the former approached significance. Evidence from biological, genetic, and other clinical studies supports the hypothesis that depressive psychosis and manic-depressive psychosis may be distinctly different types of affective disorder.
Beigel A, Murphy DL. Unipolar and Bipolar Affective IllnessDifferences in Clinical Characteristics Accompanying Depression. Arch Gen Psychiatry. 1971;24(3):215-220. doi:10.1001/archpsyc.1971.01750090021003