Dynamic Risk and Protective Factors of NSSI in Middle School Students: A Longitudinal Study.

BACKGROUND: This study aimed to use longitudinal data from 2021 to 2023 to systematically examine the risk and protective factors and mechanisms associated with nonsuicidal self-injury (NSSI) among middle school students in Jingzhou City, and to provide empirical evidence for targeted school-based psychological interventions. METHODS: A baseline survey was conducted in 2021 (T1) among 652 first-year junior high school students from two schools in Jingzhou City. In 2023 (T2), 585 participants were successfully followed up (follow-up rate: 89.72%). Participants were categorized into four groups: no NSSI, incident NSSI, NSSI remission, and persistent NSSI. Intergroup differences in characteristics were analyzed using chi-square tests, Kruskal-Wallis H tests, and post hoc comparisons. Three binary logistic regression models were constructed to explore the predictive effects of baseline (T1) factors on incident, remitted, and persistent NSSI, respectively. The significance level was set at α = 0.05. Results: The overall rate of NSSI decreased markedly from 22.05% to 8.55% over the two-year period. Multivariable analysis showed that in the model predicting NSSI remission (no NSSI group vs. remission group), individuals whose depressive symptoms decreased were significantly more likely to have discontinued NSSI (adjusted odds ratio (aOR) = 8.43, 95% confidence interval (CI): 3.01-23.60). Those with stable anxiety symptoms had a significantly higher rate of NSSI remission compared with those whose anxiety worsened (aOR = 0.35, 95% CI: 0.18- 0.67). Gender-stratified analyses showed that among boys, a reduction in internet addiction was a significantly protective factor for NSSI remission (aOR = 8.87, 95% CI: 1.81-43.48). Among girls, both a decrease in depressive symptoms (aOR = 18.53, 95% CI: 3.36-102.26) and stable anxiety symptoms (aOR = 0.31, 95% CI: 0.14-0.72) were significantly associated with NSSI remission. CONCLUSIONS: NSSI behaviors among middle school students exhibit a high remission rate (82.17%) over time. The findings underscore the close association between NSSI and dynamic psychological problems. Prevention and intervention strategies of NSSI should be developed according to the longitudinal follow-up study, such as specific interventions of internet use behaviors for males and depressive and anxiety symptoms for females.