BACKGROUND The assumption that patients with bipolar disorder make a full inter-episode recovery has been challenged by limited evidence that suggests that neuropsychological dysfunction in bipolar disorder may persist beyond episodes of illness.
AIMS To test the hypothesis that patients with euthymic bipolar disorder show neuropsychological impairment.
METHOD A battery of neuropsychological tests (assessed attention, working memory, learning and executive function) was administered to three matched groups of subjects: good-outcome patients with bipolar disorder (n = 21); poor-outcome patients with bipolar disorder (n = 20); controls (n = 20). All patients were clinically euthymic, although some had low levels of depressive symptoms.
RESULTS Patients performed worse than controls on a number of neuropsychological tests. When age, premorbid IQ and depressive symptoms were controlled for, the results indicated impairment of executive function.
CONCLUSIONS These findings provide good evidence for the existence of neuropsychological impairment in patients with euthymic bipolar disorder, although the possible effect of medication should not be overlooked. This may be of clinical relevance and raises questions about the course and outcome of the illness.