S201. HIPPOCAMPAL SUBFIELD VOLUMES AND CHANGE IN BODY MASS OVER 12 MONTHS OF TREATMENT IN FIRST-EPISODE SCHIZOPHRENIA SPECTRUM DISORDERS

BACKGROUND: In this study, we explored the relationship between hippocampal subfield volumes and change in body mass over 12 months of treatment in 90 first-episode schizophrenia spectrum disorder patients (66 males, 24 females; mean age= 24.7±6.8 years). METHODS: Body mass index was assessed in patients at baseline, and at months 3, 6, 9 and 12. Hippocampal subfields of interest were assessed using a segmentation algorithm included in the FreeSurfer 6.0 software program. RESULTS: Linear regression analysis showed a significant interactive effect between sex and anterior hippocampus size as a predictor of change in body mass over 12 months, adjusting for age, substance use, treatment duration, and posterior hippocampal volumes. In an exploratory sub-analysis, partial correlations revealed a significant association between weight gain and smaller CA1, CA3 and subiculum volumes in females, but not males, adjusting for age and substance use, with similar trends evident for the CA4 and presubiculum subfields. DISCUSSION: In conclusion, our findings suggest that smaller anterior hippocampal subfields are associated with the development of weight gain over the course of treatment in first-episode schizophrenia spectrum disorders in a sex-specific fashion, and may partly explain the more severe and ongoing increase in body mass evident for female patients.