The Maudsley Bipolar Disorder Project: Executive dysfunction in bipolar disorder I and its clinical correlates

Background: Cognitive abnormalities are increasingly recognized as a feature of bipolar I disorder (BDI,) but there is limited information regarding the pattern and severity of cognitive impairment during remission and its relationship with clinical variables. Methods: Forty-four remitted BDI patients recruited from a representative treatment sample and an equal number of matched healthy volunteers underwent comprehensive clinical and cognitive assessments. Cognitive evaluation covered the domains of IQ, memory, and executive function. The profile of cognitive deficits in patients was examined, and the correlation of executive function with clinical features and treatment variables was explored. Results: Remitted BDI patients were impaired in tests of executive function compared with healthy participants. Within the patient group, current antipsychotic treatment predicted worse performance across all executive function tests, whereas duration of illness predicted loss of inhibitory control. Residual mood symptoms, regardless of polarity, had a negative impact primarily on measures of attentional interference. Conclusions: These results suggest that impaired executive function might be an important feature of BDI. Antipsychotic treatment, duration of illness, and level of symptoms are the most significant contributors to the observed impairment.