Longitudinal effects of psychological symptoms on non-suicidal self-injury: a difference between adolescents and young adults in China

Few longitudinal studies have examined the psychological symptoms that may lead to non-suicidal self-injury (NSSI) among Chinese adolescents and young adults. This study determined the predictive effects of psychological symptoms for NSSI during a 9-month follow-up period. Data from 17,622 students, 12-24 years of age, were analyzed in a cross-sectional fashion with respect to associations between psychological symptoms and NSSI. Follow-up surveys were performed 3, 6, and 9 months later. Incident cases of NSSI during follow-up were correlated with the psychological symptoms at baseline. A total of 3,001 (17.0 %) students reported that they had NSSI in the 12 months before the initial assessment. The total rate of NSSI revealed no statistically significant differences by gender, but marked differences between grades. The response rate 3, 6, and 9 months later was 91.8, 81.8, and 79.1 %, respectively. Our cross-sectional study demonstrated statistically significant associations between emotional problems, conduct problems, social adaptation problems, psychological problems, and NSSI (P < 0.01). In the longitudinal study, emotional problems, conduct problems, social adaptation problems, and psychological problems at baseline had statistically significant associations with incident NSSI in follow-up involving the adolescents, while the association in young adults was attenuated after adjustment for confounding variables. Moreover, psychological symptoms at baseline showed a monotonic dose-response relationship with NSSI in follow-up involving adolescents. The findings suggest that adolescents with psychological symptoms are a group with elevated risks for later NSSI. The prevention programs of NSSI should target attenuating the severity of psychological symptoms.