Neurocognitive dysfunctions in euthymic bipolar patients with and without prior history of alcohol use

Despite the additional complications associated with alcohol misuse in bipolar populations, it is generally the case that studies exploring neurocognitive aspects of bipolar disorder specifically exclude patients with alcohol abuse or dependence. Given the role of cognitive dysfunctions in overall illness outcome, this study addressed the neurocognitive functioning of patients with a history of alcohol abuse or dependence as compared to bipolar patients without such a history and healthy controls.

The study sample included 100 subjects: 65 bipolar patients, 30 of whom with a history of alcohol abuse or dependence and 35 without a previous history of alcohol abuse or dependence, based on DSM-IV criteria, and a control group of 35 healthy subjects. Comprehensive neuropsychological tests were carried out during strictly defined clinical remission. Differences between groups were analyzed and a linear regression analysis was undertaken to establish predictors of psychosocial functioning as measured using the Global Assessment of Functioning. Data were collected from September 2006 to July 2007.

Bipolar patients with a history of alcohol abuse or dependence obtained lower scores in the interference task of the Stroop test compared to the control group. Both patient groups showed a poorer performance in some verbal memory and executive function measures than healthy controls. Verbal learning impairment was significantly associated with poor psychosocial functioning.

Cognitive dysfunctions appeared to be more strongly associated with bipolar disorder than with the "history of alcohol abuse or dependence" factor. Bipolar patients with history of alcohol misuse may have greater difficulties of inhibitory control, probably due to higher impulsivity.