Cognitive impairment in individuals with bipolar disorder with and without comorbid alcohol and/or cocaine use disorders.

BACKGROUND: Bipolar disorder (BD) frequently co-occurs with substance use disorders (SUDs), and both are associated with cognitive impairment. This study compares cognition between individuals with BD with and without current alcohol use disorder (AUD), cocaine use disorder (CUD), or both, as these disorders may be linked with additive cognitive impairment.
METHODS: Baseline data were analyzed from five clinical studies of individuals with the aforementioned disorders (N = 373). Participants were grouped as follows: BD-only, BD + AUD, BD + CUD, or BD + AUD + CUD. Cognition was assessed with the Rey Auditory Verbal Learning Test (RAVLT) (verbal learning and memory) and Stroop Color Word Test (executive function). Multiple linear regression models determined if SUD diagnosis, among other demographic and clinical variables, predicted each cognitive test's T-score. Regression equations were used to compute each group's mean T-scores.
RESULTS: All groups demonstrated below-average mean T-scores on all tests, with no significant between-group score differences. RAVLT total T-scores were lower than Stroop color-word T-scores within all groups (non-overlapping 95% confidence intervals). Higher daily cocaine use predicted higher Stroop T-scores (p < 0.01) and RAVLT delayed recall T-scores (p < 0.05). No other non-demographic variable, including AUD/CUD group status, predicted cognitive performance. LIMITATIONS: A full cognitive battery and some relevant variables (e.g. BD lifetime illness course) were not available. Many participants (42.1%) had additional SUDs.
CONCLUSIONS: BD with and without AUD/CUD was found to be associated with greater deficits in verbal learning and memory than in executive function. Addressing these impaired domains in dually-diagnosed patients may improve treatment and functional outcomes.