Background: Bipolar disorder is associated with persistent deficits in neuropsychological functions, which may be considered as an endophenotype. This study aimed to compare neuropsychological functions, including cognitive flexibility, inhibition, working memory, selective attention, and sustained attention, in patients with bipolar I disorder in the euthymic phase and healthy individuals.
Methods: In this causal-comparative study, 30 patients with bipolar I disorder in the euthymic phase and 30 healthy individuals, matched for age and gender, were selected through purposive sampling. Neuropsychological assessments were conducted using computerized tools, including the Wisconsin Card Sorting Test (cognitive flexibility), Go/No-Go (inhibition), Wechsler and N-Back (working memory), Stroop (selective attention), and CPT (sustained attention). Data were analyzed using multivariate analysis of variance (MANOVA) in SPSS version 26.
Findings: The results revealed significant differences between the two groups in several indices. Patients with bipolar disorder exhibited poorer performance compared to the healthy group in cognitive flexibility (perseverative errors, correct responses, and other errors), inhibition (commission error score and percentage), N-Back working memory (omission, correct response count and percentage, mean response time, and standard deviation of response time), and selective attention (number of congruent and incongruent errors, incongruent omissions, and number of correct congruent and incongruent responses). No significant differences were observed in other subscales despite the poorer performance of patients.
Conclusion: It appears that bipolar disorder selectively impacts neuropsychological functions, with these deficits persisting even during the euthymic phase. These findings underscore the importance of cognitive assessment and the consideration of neuropsychological rehabilitation interventions for these patients.