Neurocognitive markers of psychosis in bipolar disorder: A meta-analytic study

Abstract

Background It has been suggested that patients with psychotic bipolar disorder (BDP+) might have more severe cognitive deficits than non-psychotic bipolar disorder patients (BDP−). However, only a handful of studies have compared cognition between BDP+ and BDP−. Our aim was to examine cognitive deficits associated with psychosis in BD using meta-analytic methods. Methods After a systematic literature review, we conducted a meta-analysis on studies that compared cognition in bipolar disorder (BD) patients with and without a history of psychosis. In addition the effects of clinical and demographic confounder factors were examined with meta-regression analyses. Results There were no significant differences for gender and duration of illness between groups. Compared with BDP−, BDP+ patients had more inpatient admissions, a younger onset of illness and used antipsychotics more commonly. BDP+ patients also performed significantly worse in 4 of 6 cognitive domains (planning and reasoning, working memory, verbal memory and processing speed). There were also differences for some individual tasks ( List Learning, Delayed Recall, Trail Making B, Wisconsin Card Sorting Test, Digits Backwards, Stroop Interference, Semantic Fluency) with BDP+ patients showing moderately greater impairment on these tasks ( d = 0.30–0.55). Conclusions A history of psychosis is associated with greater severity of cognitive deficits in BD. However, this effect is modest, and these findings do not suggest a complete categorical distinction between BDP+ and BDP−. Psychosis in BD might reflect partly distinct neurobiological processes.