S139. Accelerated Cortical Thinning Within Structural Brain Networks is Associated With Irritability in Youth

Background: Irritabilityis an important dimension of psychopathology that spans multiple clinical diagnostic categories, yet its relationship to patterns of brain development remains sparsely explored. Here, we examined how trans-diagnostic symptoms of irritabilityrelate to the development of structural brain networks. Methods: All participants (n=144, 87 females) completed structural brain imaging with 3 Tesla MRI at two timepoints (mean age at follow-up: 20.9 years, mean inter-scan interval: 5.1 years). Irritabilityat follow-up was assessed using the Affective Reactivity Index, and cortical thickness was quantified using Advanced Normalization Tools software. Structural covariance networks were delineated using non-negative matrix factorization, a multivariate analysis technique. Both cross-sectional and longitudinal associations with irritabilityat follow-up were evaluated using generalized additive modelswith penalized splines. The False Discovery Rate(q