Cognitive Impairment and its Associations with the Path of Illness in Affective Disorders: A Comparison Between Patients with Bipolar and Unipolar Depression in Remission

The goals of this study were to investigate differences in neurocognitive performance between groups of patients with unipolar major depressive disorder (MDD) or bipolar I disorder (BD-I) in a euthymic state, and to analyze associations among cognitive performance, sociodemographic and clinical variables, and global functioning. The study evaluated 25 outpatients with MDD and 25 outpatients with BD-I. Controls consisted of a sample of 29 healthy adult volunteers. All of the subjects were administered a battery of neuropsychological tests (Babcock Story Recall Test, Wisconsin Card Sorting Test, Trail Making Test Part B, Stroop Color and Word Test, Symbol-Number Association Test, and Digit Span). Patients demonstrated reduced performance on tasks involving executive functions (Trail Making Test Part B and Wisconsin Card Sorting Test) and attention (Digit Span and Symbol-Number Association Test) compared with healthy controls. Performance on neurocognitive tasks did not differentiate patients with MDD from those with BD-I. Improved performance on tasks that assessed executive functions by patients with BD-I and MDD, considered as a single group, was associated with better global functioning, even when controlling for several sociodemographic and clinical confounders. Patients with MDD and BD-I showed a similar profile of information-processing deficits and similar global functioning. Global functioning was also moderately associated with performance on executive function tasks.