Abstract
BACKGROUND: Amid the global escalation of adolescent depression and non-suicidal self-injury (NSSI), childhood trauma has been identified as a critical risk factor, yet how specific trauma subtypes contribute to NSSI remains unclear. This study aims to explore the relationship between childhood trauma subtypes and NSSI in depressed adolescents, focusing gender differences, and verify the mediating role of rumination. METHODS: This cross-sectional study included 2,006 clinically depressed adolescents (aged 10-19), who were recruited through convenience sampling from a psychiatric hospital in China (2024-2025). Validated scales (Childhood Trauma Questionnaire [CTQ], Ruminative Response Scale [RRS], Ottawa Self-Injury Inventory [OSI]) were administered. Binary logistic regression, subgroup analysis, and mediation analysis were used to examine the relationships between variables. RESULTS: NSSI prevalence reached 69.3% in depressed adolescents (female: 77.6% vs. male: 52.1%). Emotional neglect (EN, odds ratio [OR] = 1.82), emotional abuse (EA, OR = 2.06), and physical abuse (PA, OR = 2.55) were associated with NSSI. Gender difference analysis revealed that females were more sensitive to EN (OR = 2.30) and EA (OR = 2.06), while males were more sensitive to EA (OR = 2.07) and PA (OR = 2.12). A single trauma subtype significantly increased the risk of NSSI in females, whereas males required at least two trauma subtypes to significantly increase NSSI risk. Rumination played a mediating role between all trauma subtypes and NSSI, with sexual abuse (SA) showing the highest mediation effect (78.02%), indicating a full mediation effect. CONCLUSIONS: The childhood trauma-NSSI association in depressed adolescents demonstrates gender difference, with rumination functioning as the central mechanistic pathway. Interventions must prioritize trauma subtype- and gender-tailored strategies to disrupt rumination pathways. CLINICAL TRIAL NUMBER: Not applicable.