Comparison of neurocognitive function in major depressive disorder, bipolar disorder, and schizophrenia in later life: A cross-sectional study of euthymic or remitted, non-demented patients using the Japanese version of the Brief Assessment of Cognition in Schizophrenia (BACS-J).

Major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia (SZ) are associated with cognitive dysfunction both in adulthood and in later life. In this study, we directly compared neurocognitive function between these three conditions in later life, employing stringent definitions of euthymia and symptomatic remission. Cognitive function in 60 elderly outpatients with MDD, BD, or SZ (20 patients per group) was assessed using the Japanese version of the Brief Assessment of Cognition in Schizophrenia. Patients with MDD had significantly higher z scores than both the other groups with large or moderately large effect sizes, for verbal fluency, attention and speed of information processing, and composite scores. In contrast, there were no significant differences in the degree of neurocognitive impairment between patients with BD and SZ. In later life, patients with BD and SZ showed a similar degree of neurocognitive impairment, while patients with MDD showed smaller impairments in several neurocognitive domains compared to patients with either of the other two disorders.