Few studies have investigated the longitudinal effects of treatment-emergent metabolic syndrome changes on cognitive performance in first-episode psychosis. The aim of the present study was to determine the associations between changes in metabolic syndrome constituent component over 12 months of treatment and end-point cognitive performance in schizophrenia spectrum disorders. This single site-cohort study included 72 minimally treated or antipsychotic-naïve first-episode patients. Cognitive performance was evaluated using the MATRICS Consensus Cognitive Battery (MCCB). Our primary objective of interest was the relationship between metabolic syndrome constituent component changes over 12 months of treatment and end-point cognitive performance. Secondary objectives included investigating whether this relationship was affected by age, sex, antipsychotic dose, treatment duration and substance use. Weight gain predicted better overall cognition (p = 0.02) at end-point, adjusting for age, sex, substance use, baseline cognitive score and BMI, modal antipsychotic dose and treatment duration. Weight loss (p = 0.04) and substance use (p = 0.01) were both associated with poorer working memory performance at end-point. Low baseline BMI showed differential effects on end-point working memory performance in substance users (unfavorable) compared to non-users (favorable) (p < 0.05). In conclusion, weight gain over the course of antipsychotic treatment is associated with better overall cognitive performance and the working memory domain in first-episode schizophrenia spectrum disorder patients. In contrast, low baseline BMI may represent an unfavorable marker in substance users, who demonstrated weight loss compared to non-users.
Keywords: Cognitive performance; First-episode schizophrenia spectrum disorders; MCCB; Weight gain; Working memory.