Reciprocal associations between peer problems and non-suicidal self-injury throughout adolescence

Background Peer problems have emerged as important predictors of Non-Suicidal Self-Injury (NSSI) development during adolescence. However, the possibility that adolescents who engage in NSSI may, in turn, be at increased risk for experiencing difficulties with their peers has rarely been examined. This study investigated the reciprocal associations between peer problems (e.g. peer victimization, friendship stress and loneliness) and NSSI throughout adolescence, distinguishing between- and within-person effects. Method Participants were 866 adolescents (54.5% females; M-age = 13.12 years, SD = 0.78), who took part in six waves of data collection. Adolescents completed self-report measures of NSSI, friendship stress and loneliness and they took part in a peer nomination procedure to assess peer victimization. Random Intercept Cross-Lagged Panel Models (RI-CLPMs) were used to estimate within-person cross-lagged effects between each peer problem and NSSI from Grade 7 to 12. Results After accounting for between-person associations between peer problems and NSSI, results indicated that higher-than-usual levels of NSSI predicted higher-than-usual levels of adolescents' own friendship stress, loneliness and peer victimization at the subsequent time point. Yet, sensitivity analyses revealed that most of these effects were strongly attenuated and explained by within-person fluctuations in depressive symptoms. No within-person cross-lagged effects from peer problems to NSSI were found. Conclusions Findings highlight that the associations between peer problems (i.e. friendship stress, loneliness) and NSSI may be largely explained by shared underlying factors; yet, some evidence also suggests that NSSI engagement may increase adolescents' risk to experience difficulties in the relationships with their peers, in part via increases in depressive symptoms.