Comparison of mania and depression after brain injury: causal factors.

Patients who developed secondary mania after brain injury (N = 17) had a significantly greater frequency of injury to right hemisphere areas connected with the limbic system than poststroke patients with major depression (N = 31), who had injury primarily in the left frontal cortex and basal ganglia. For patients without mood disturbance after brain injury (N = 28), the location of the lesion was not significant. Secondary mania patients also had a significantly greater frequency of family history of affective disorder than did the other two groups. These results suggest that an interaction between injury to certain areas of the right hemisphere and genetic factors or other neuropathological conditions produces secondary mania.