[EN] First-episode psychosis (FEP) patients show structural brain abnormalities at the first episode. Whether the cortical changes that follow a FEP are progressive and whether age at onset modulates these changes remains unclear. This is a multicenter MRI study in a deeply phenotyped sample of 74 FEP patients with a wide age range at onset (15-35 years) and 64 neurotypical healthy controls (HC). All participants underwent two MRI scans with a 2-year follow-up interval. We computed the longitudinal percentage of change (PC) for cortical thickness (CT), surface area (CSA) and volume (CV) for frontal, temporal, parietal and occipital lobes. We used general linear models to assess group differences in PC as a function of age at FEP. We conducted post-hoc analyses for metrics where PC differed as a function of age at onset. We found a significant age-by-diagnosis interaction effect for PC of temporal lobe CT (d=0.54; p=002). In a post-hoc-analysis, adolescent-onset (≤19y) FEP showed more severe longitudinal cortical thinning in the temporal lobe than adolescent HC. We did not find this difference in adult-onset FEP compared to adult HC. Our study suggests that, in individuals with psychosis, CT changes that follow the FEP are dependent on the age at first episode, with those with an earlier onset showing more pronounced cortical thinning in the temporal lobe.We are extremely grateful to all subjects who took part in this study. This work was supported by CIBERSAM; Instituto de Salud Carlos III, Spanish Ministry of Science and Innovation (PI081203, PI08/0208; PI11/00325; PI1101686, PI14/00612, PI17/01997, PI20/01342), co‐financed by the ERDF from the European Commission “A way of making Europe”, European Union Seventh Framework Program (FP7- HEALTH-2013-2.2.1-2-603196 [Project PSYSCAN]), EU H2020 (IMI‐2 Joint Undertaking under grant agreements 115916 (project PRISM) and 777394 (project AIMS‐2‐TRIALS)), Madrid Regional Government (S2017/BMD‐3740, and AGES-CM-2-CM) and European Union Structural Funds; Fundación Familia Alonso, Fundacion Mutua Madrileña, and Fundación Alicia Koplowitz
