The longitudinal associations between nature exposure and non-suicidal self-injury among Chinese early adolescents: a moderated mediation model

Abstract

Non-suicidal self-injury (NSSI) is a major public health concern during adolescence, yet relatively little is known about whether daily exposure to natural environments is prospectively associated with adolescents’ self-reported NSSI frequency. This study examined the longitudinal association between nature exposure and NSSI among Chinese early adolescents, and further tested whether mindfulness mediated this association and whether these pathways varied by gender. A three-wave longitudinal design with 6-month intervals was used. A total of 1,854 adolescents participated at T1, and the final analytic sample consisted of 1,048 adolescents who completed all three waves and were successfully matched across waves. Nature exposure was assessed at Time 1, mindfulness at Time 2, and NSSI at Time 1 and Time 3. PROCESS Model 8 was used to test the mediating role of mindfulness and the moderating role of gender, controlling for baseline NSSI, age, parental monthly income, and parental educational level. T1 nature exposure positively predicted T2 mindfulness ( B  = 0.25, p < 0.001), and T2 mindfulness negatively predicted T3 NSSI scores ( B  = -0.03, p  = 0.008). The direct effect of T1 nature exposure on T3 NSSI was not significant after controlling for covariates ( B  = 0.000, p  = 0.933). The conditional indirect effect through T2 mindfulness was significant among girls ( B  = -0.0083, 95% Bootstrap CI [-0.015, -0.002]), but not among boys ( B  = -0.0030, 95% Bootstrap CI [-0.008, 0.000]). The index of moderated mediation was significant (Index = 0.0053, 95% Bootstrap CI [0.000, 0.01]). These findings suggest that T1 nature exposure was prospectively associated with lower subsequent NSSI scores through a mindfulness-related indirect pathway, and that this indirect pathway differed by gender. Given the observational design and the small magnitude of the indirect effects, the findings should be interpreted as prospective associations rather than evidence that nature exposure prevents NSSI or reduces clinical risk.