Neuropsychological impairment among manic, depressed, and mixed-episode inpatients with bipolar disorder.

Previous research has demonstrated broad neurobehavioral abnormalities in bipolar affective disorder (cf. G. Cassens, L. Wolfe, & M. Zola, 1990). However, there have been no comparisons of neuropsychological function across patients with manic, depressed, or mixed subtypes. In the present study, 37 manic, 24 mixed-episode, and 25 depressed bipolar I inpatients and 34 control subjects were administered a brief battery of neuropsychological tests. The multivariate and univariate effects of participant group on the neuropsychological measures were uniformly significant (p < .05). Planned contrasts revealed that the bipolar participants performed worse than the controls, and few differences existed between the 3 patient groups. Additionally, the bipolar groups were impaired on 50% of the test battery. These abnormalities were unlikely attributable to differences in psychiatric symptomatology, medical illness, comorbid psychiatric diagnoses, or medication status. Findings imply that acute mood disturbance during bipolar disorder yields significant neurobehavioral dysfunction.