Effect of symptoms on executive function in bipolar illness

The relationship between cognitive function and symptomatology in bipolar disorder is unclear. This study assessed executive function during the manic, depressed and remitted stages of bipolar I disorder.

Tasks assessing phonological and semantic verbal fluency, the Hayling Sentence Completion Test, the Stroop Neuropsychological Screening Test and the Cognitive Estimates Test were administered to manic (n = 15), depressed (n = 15), and remitted (n = 15) bipolar I patients, and to healthy controls (n = 30). Multiple regression analyses and analyses of covariance were used to identify potential determinants of executive dysfunction in the three bipolar groups.

Executive function deficits were particularly associated with the manic state. In general, manic patients performed less accurately than the remitted and depressed groups, and their performance deficit was related to the severity of positive thought disorder. The depressed and remitted bipolar groups showed a less widespread pattern of impairment. Deficits in response initiation, strategic thinking and inhibitory control were evident in all the bipolar groups.

Executive function deficits in bipolar I disorder are most evident during mania, and are particularly associated with formal thought disorder. However, deficits in response initiation, strategic thinking and inhibitory control may be more related to the underlying disorder than a particular symptom profile.