Disentangling Environmental and Genetic Influences on Associations Between Childhood Bullying Victimization and...

Psychotic-like experiences (PLEs) are common in youth and predict later mental health problems. Bullying victimization is a robust environmental risk factor for psychopathology including PLEs, but whether its association with PLEs reflects shared genetic liability, individual-specific putatively causal effects, or reciprocal processes is unclear. We analyzed seven waves of longitudinal data from the Adolescent Brain Cognitive Development (ABCD) Study, examining associations across the sample in addition to leveraging within-family comparisons among twin and sibling pairs who were concordant or discordant for exposure to bullying victimization. Using linear mixed-effects and cross-lagged models, we found that youth reporting bullying victimization were more likely to endorse significantly distressing PLEs than non-victimized youth (caregiver-reported odds ratio=2.35; youth-reported odds ratio=4.10). Longitudinal analyses revealed bidirectional associations: prior bullying predicted subsequent increases in distressing PLEs, and prior PLEs predicted elevated risk of later bullying victimization. Genetically-informed within-family analyses indicated that both shared genetic influences and individual-specific factors contributed to these associations; critically, bullied youth exhibited higher odds of distressing PLEs than their non-exposed siblings (youth-reported odds ratio=6.67; 95%CI:4.96-8.96), consistent with an individual-specific effect of victimization. Together, these findings suggest that bullying and PLEs are linked through reciprocal developmental processes that are not fully explained by familial confounding. More broadly, our results highlight bullying prevention as a plausible leverage point for reducing early psychosis-spectrum risk and illustrate the value of integrating within-family designs to help disentangle genetic and environmental contributions to mental health outcomes in adolescence.