IntroductionIt is well established that patients with bipolar disorder in acute manic-depressive states show considerable cognitive impairment (1-3). In recent years, however, there has been a strong shift towards studying neurocognitive functions in euthymic patients with bipolar disorder. These Torres IJ, Boudreau VG, Yatham LN. Neuropsychological functioning in euthymic bipolar disorder: a meta-analysis.Objective: Although cognitive deficits are prominent in symptomatic patients with bipolar disorder, the extent and pattern of cognitive impairment in euthymic patients remain uncertain. Method: Neuropsychological studies comparing euthymic bipolar patients and healthy controls were evaluated. Across studies, effect sizes reflecting patient-control differences in task performance were computed for the 15 most frequently studied cognitive measures in the literature. Results: Across the broad cognitive domains of attention ⁄ processing speed, episodic memory, and executive functioning, medium-to-large performance effect size differences were consistently observed between patients and controls, favoring the latter. Deficits were not observed on measures of vocabulary and premorbid IQ. Conclusion: Meta-analytic findings provide evidence of a trait-related neuropsychological deficit in bipolar disorder involving attention ⁄ processing speed, memory, and executive function. Findings are discussed with regard to potential moderators, etiologic considerations, limitations, and future directions in neuropsychological research on bipolar disorder.