The mediating roles of stressful life events and negative affect in the relationship between childhood maltreatment and non-suicidal self-injury among clinical adolescents.

Non-suicidal self-injury (NSSI) is a significant public health concern among adolescents, particularly in psychiatric settings, where prevalence rates exceed those observed in the general community. Childhood maltreatment (CM) is a known risk factor for NSSI; however, the mechanisms linking CM to NSSI are not fully understood. This study explored the mediating roles of stressful life events (SLEs) and negative affect (depression and anxiety) in the relationship between CM and NSSI, grounded in the cumulative adversity theory. In this cross-sectional survey, 226 Chinese adolescents (Mage = 14.76, SD = 1.70) admitted to a psychiatric unit participated. Measures included the Childhood Trauma Questionnaire (CTQ-SF), the Adolescent Self-Rating Life Events Checklist (ASLEC), the Patient Health Questionnaire-9 (PHQ-9), the Generalized Anxiety Disorder-7 (GAD-7), and the Ottawa Self-Injury Inventory Chinese Revised Edition (OSIC). Structural equation modelling (SEM) was used to analyze mediation pathways. Stressful life events and negative affect fully mediated the relationship between childhood maltreatment and NSSI. Specifically, CM indirectly influenced NSSI severity through increased negative affect ( = 0.088, 95% CI: 0.014-0.186,  = .039) and through a sequential pathway involving both SLEs and negative affect ( = 0.137, 95% CI: 0.072-0.251,  = .002). However, the pathway from CM to NSSI via SLEs alone was not significant ( = -0.053, 95% CI: -0.267 to 0.093,  = .565). The findings align with cumulative adversity theory, suggesting that childhood maltreatment elevates NSSI risk by increasing emotional distress in response to subsequent stressful life events. Targeted interventions should focus on helping at-risk adolescents manage stress and strengthen emotional resilience.