| 【Abstract】 Background Non-suicidal self-injury (NSSI) among adolescents has become a global public health concern. Anxiety and depression are considered key factors influencing NSSI, while social support may play a protective role in alleviating emotional and behavioral issues. However, existing research has primarily focused on the direct impact of individual factors on NSSI, with insufficient exploration of the combined effects of anxiety, depression, and social support. Objective This study aimed to investigate the direct effect of anxiety on NSSI, the mediating role of depression in this relationship, and the moderating role of social support, providing a scientific basis for the prevention and intervention of adolescent NSSI. Methods In February 2022, a total of 40 820 students from grades 7 to 12 across 10 middle schools in a district of Chengdu were selected as participants. The Generalized Anxiety Disorder Scale (GAD-7), Patient Health Questionnaire-9 (PHQ-9), Social Support Scale for Adolescents (SSSUS), and Adolescents’ Self-Injury Questionnaire (ASIQ) were used to assess anxiety, depression, social support, and NSSI, respectively. Pearson correlation analysis was conducted to examine the relationships among variables. Hayes’ PROCESS macro version 3.5 was employed to perform moderated mediation model analyses, with the bootstrap method used to test mediation and moderation effects. Simple slope analysis was conducted to compare interaction effects. Results Among 34 534 valid respondents (84.60%), 542 adolescents (1.57%) reported engaging in NSSI. Significant differences in gender, GAD-7 scores, PHQ-9 scores, and SSSUS scores were observed between the NSSI and non-NSSI groups (χ2/t=62.889, 71.120, 94.365, -41.464, P<0.01). GAD-7 scores were positively correlated with ASIQ scores and PHQ-9 scores (r=0.158, 0.166, P<0.01). PHQ-9 scores were positively correlated with ASIQ scores (r=0.364, P<0.01) but negatively correlated with SSSUS scores (r=-0.290, P<0.01). SSSUS scores were negatively correlated with ASIQ scores (r=-0.247, P<0.01). Depression partially mediated the relationship between anxiety and NSSI (effect value=0.544, 95% CI: 0.162~0.944), accounting for 35.79% of the total effect. Social support moderated the relationship between depression and NSSI (effect value=-0.082, 95% CI: -0.135~-0.029). Conclusion Anxiety not only directly influences adolescent NSSI but also indirectly exacerbates it through the mediating effect of depression, while social support mitigates the impact of depression on NSSI. |