Disentangling the Link Between Bullying Exposure, Psychosis-like Experiences, and Functional Network Connectivity in Adolescence

Bullying is an adverse childhood experience affecting up to one-third of the global population and linked to psychosis-like experiences (PLEs), which increase the risk of psychotic disorders. This study aimed to investigate the association between the severity and persistence of bullying and PLEs and the neurobiological pathways from bullying to psychosis-like experiences by assessing multiscale brain functional network connectivity (msFNC). We used data from the ABCD Study, a large, ongoing, multisite, population-based prospective cohort study following U.S. adolescents. We included adolescents with complete bullying and PLEs assessments at the 2- and 3-year follow-ups (T1: n=10,939; T2: n=10,102). We examined the associations between bullying severity and temporal exposure and PLEs using linear mixed-effects models. In a 2-year rsfMRI subsample (n=5,280), we used a Neuromark framework to analyze whether msFNC mediated the pathway from bullying to PLEs. Higher PLEs were associated with the presence and severity of bullying (non-bullied vs. mild bullying: d=-0.19, CI: -0.39 to -0.19, p<0.0001; moderate vs. severe bullying: d=-0.49, CI: -0.69 to -0.56, p<0.0001). When bullying ceased, PLEs returned to non-bullied levels (d=-0.13, CI:-0.20 to -0.05, p=0.16), whereas persistence over two years led to greater elevations (d=-0.36, CI:-0.43 to -0.29, p<0.0001). We observed similar patterns for non-paranoid and hallucination-like experiences and their distress. msFNC in paralimbic, default mode, central executive, somatomotor, temporoparietal, insulotemporal, and frontal networks mediated the association. Bullying is time- and dose-dependently associated with psychosis-like outcomes. msFNC between functional brain networks is a novel neurobiological pathway that mediates the link from bullying to PLEs.