Cognitive Performance associated to functional outcomes in stable outpatients with schizophrenia

BACKGROUND–OBJECTIVE: Prevalence data of cognitive impairment in Schizophrenia based on large population samples are scarce. Our goal is to relate cognition and functional outcomes, and estimate prevalence of cognitive impairment in a large sample of schizophrenia outpatients treated with second-generation antipsychotics. METHOD: A cross-sectional outpatient evaluation conducted during follow-up visits. Selection criteria included six-months stable treatment. The brief battery, EPICOG-SCH, covered four cognitive domains related to functional outcomes: working memory (WAIS-III-Letter-Number-Sequencing), executive function (Category Fluency Test; CFT), verbal memory (WMS-III-Logical-Memory), and information processing speed (Digit-Symbol-Coding and CFT). Clinical severity and functional impairment were assessed with CGI-SCH and WHO DAS-S. Impairment prevalence was calculated at ≤ 1.5 SD. RESULTS: Among patients recruited (n = 848) in 234 participating centers, 672 were under 6-month treatment. 61.5% (n = 413) reported cognitive impairment according to CGI-SCH Cognitive Subscale. Estimated prevalences were 85.9% (95% CI 85.6–86.2%) CFT-Fruits; 68.3% (95% CI 67.8–68.8%) CFT-Animals; 38.1% (95% CI 37.5–38.3%) Digit-Symbol-Coding; 24.8% (95% CI 24.1–25.5%) Verbal Memory-Units; 20.9% (95% CI 20.2–21.6%) Letter-Number Sequencing; 11.7% (95% CI 11.0–12.4%) Verbal Memory-Items. Negative and Depressive symptoms, Deficit Syndrome, and functional disability were related to poor performance. Functional disability was predicted by CGI-SCH-Overall severity (OR = 1.34635, p < 0.0001), CGI-SCH-Negative Symptoms (OR = 0.75540, p < 0.0001), working memory (Letter-Number-Sequencing) (OR = − 0.16442, p = 0.0004) and the time-course (OR = 0.05083, p = 0.0094), explaining 47% of the observed variability. CONCLUSION: Most prevalent impairments were on executive function and processing speed domains; however, working memory showed the strongest relationship to functional disability. Monitoring cognitive function during follow up is critical to understand patient’s everyday functional capacity.