2.32 LONGITUDINAL CHANGES IN HIPPOCAMPAL VOLUME IN ADOLESCENTS WITH PSYCHOTIC SYMPTOMS: RELATIONSHIP TO FUNCTIONING AND ADVERSE LIFE EVENTS

Objectives: The present study aimed to analyze a change in hippocampal volume at baseline and a 2-year follow-up in a sample group of school-going adolescents who reported psychotic experiences compared with control adolescents. We also wished to investigate the role of functioning and stressful life events in influencing hippocampal volume. Methods: A nested case-control study of 50 community-based adolescents aged 13-16 years living in Ireland (25 with psychotic experiences and 25 without psychotic experiences), controlled for nonpsychotic psychopathology. All participants were assessed clinically using the psychosis section of the Schedule for Affective Disorders and Schizophrenia for School-aged Children (K-SADS) and Global Assessment of Functioning (GAF) at baseline and at 2- year follow-up. Neuroimaging was conducted on the same Philips Intera Achieva 3.0 Tesla MR system at both time points. For the analysis of the data, we used the mixed-model repeated measures to explore the effects of the following interactions: group x time interaction between the groups for hippocampus (whole hippocampus, subiculum, and CA1) during the 2-year follow-up (controlling for age and gender, functioning and bullied). In addition, we studied INTER and INTRA group differences during the 2-year follow-up. Results: At baseline, there were no significant differences between the psychosis experiences (PE) group and the control (CON) group in age, gender, or other diagnosis. However, there were significant differences between the groups in relation to global functioning and bullying (P < 0.05). We found significant differences in the right whole hippocampus and right subiculum between PE and CON group at baseline and at 2-year follow-up (P < 0.05). There were significant differences between the PE and CON group in the left hippocampus at baseline (and a trend toward significance at 2-year follow-up), and there were significant differences in the left subiculum between groups at baseline and at 2-year follow-up (P < 0.05). In the left and right hippocampi, there was no group x time interaction during the 2-year follow-up. Conclusions: Early hippocampal reductions, specifically in the subiculum, may play a role in increasing vulnerability to psychosis and stressful life events, such as bullying, and may play an important role to explain neuroanatomical hippocampal changes in adolescents with psychotic experiences.