Wisconsin Card Sorting Test performance in bipolar disorder: effects of mood state and early course

Patients experiencing an acute mood episode of bipolar disorder are impaired on cognitive tests of executive functioning when compared with healthy subjects. However, it is unclear to what extent executive dysfunction exists (i) during syndromal remission, when mood symptoms are attenuated, and (ii) during the early course of bipolar disorder.

To clarify these issues, we examined retrospective data on a standard clinical version of the Wisconsin Card Sorting Test (WCST) administered to 25 euthymic, 21 first-episode manic or mixed, and 34 multiple-episode manic or mixed patients with bipolar I disorder, and 48 healthy comparison subjects. These groups were compared on five WCST measures of executive ability.

On all but one measure the healthy group's performance was superior to that of both first- and multiple-episode groups. The euthymic group outperformed the multiple-episode group, but performed similarly to the first-episode group on all but one measure. The healthy and euthymic groups did not differ significantly on any measure. Effect sizes ranged from small to moderate.

Executive dysfunction may be a mediating vulnerability indicator of bipolar disorder that is strongly related to mood state, but only modestly related to chronicity of illness during the early disease course.