Community transition at younger ages contributes to good cognitive function outcomes in long-term hospitalized patients with schizophrenia spectrum disorder: A fifteen-year follow-up study with group-based trajectory modeling.

Aim Cognitive dysfunction is a core symptom of schizophrenia spectrum disorder, but the reported long-term cognitive outcomes are heterogeneous. This study aimed to elucidate the long-term trajectories of patients with schizophrenia spectrum disorder who transitioned to community dwelling with integrated care, and to identify predictors of successful community reintegration. Methods After the closure of a psychiatric hospital, 78 patients with schizophrenia spectrum disorder (mean age: 54.6 years) were transferred to the community. We assessed patients' cognitive function over 15 years with the Mini-Mental State Examination (MMSE) and analyzed the scores every 3 years. Forty-four patients completed all assessments. Results The mean MMSE score at discharge was 25.8, which changed to 26.8 after 3 years and 25.3 after 6 years. After 12 and 15 years, it had decreased significantly to 23.3 and 23.0, respectively. Group-based trajectory modeling identified two groups of patients: a 'poor-outcome' group (63.4%), showing a decline in scores after maintaining post-discharge levels for several years, and a 'good-outcome' group (36.6%), maintaining post-discharge scores after showing improved scores. Conclusion Considering the significant difference in age between the aforementioned groups (P = 0.040), we suggest that community transitions at younger ages contribute to better cognitive function and adaptation to community life. Even middle-aged and elderly patients with chronic schizophrenia spectrum disorder showed improved or maintained cognitive function at least 3 years after discharge, and the good-outcome group maintained cognitive function over 15 years. Improvements were dominated primarily by age at discharge, with cognitive function being maintained longer in patients in the good-outcome group.