Echoes of Trauma: Multi‐Timescale Pathways Linking Childhood Trauma to Adolescent Non‐Suicidal Self‐Injury via Social Exclusion

BACKGROUND: Non-suicidal self-injury (NSSI) is common during adolescence and is robustly associated with childhood trauma. OBJECTIVES: The present study examined how early trauma translates into long-term vulnerability and daily risk of NSSI. METHODS: Using a multi-timescale integrative design, this study combined two-wave longitudinal survey data (N = 1328) with a 13-day daily diary study (N = 287) to examine long-term and daily processes linking childhood trauma, social exclusion, and adolescent NSSI. RESULTS: Childhood trauma was directly associated with higher levels of NSSI and indirectly related to NSSI through both social ignoring and social rejection. These pathways were consistently supported across long-term and daily timescales. In addition, marked heterogeneity emerged in the rejection-NSSI association, with distinct risk patterns observed across levels of trauma exposure. CONCLUSION: Grounded in developmental psychopathology and interpersonal stress frameworks, this study integrates longitudinal and intensive daily data to show how distal childhood trauma contributes to adolescent NSSI through proximal social experiences. The findings provide empirically grounded guidance for refined risk identification and timing-sensitive intervention in adolescent populations.