Trajectories of suicide ideation and nonsuicidal self-injury among adolescents in Mainland China: Peer predictors, joint development, and risk for suicide attempts

Objective: This study expanded knowledge about the development of suicide ideation and nonsuicidal self-injury (NSSI) among adolescents by investigating (a) peer experiences as predictors of trajectories of suicide ideation and NSSI, (b) the joint development of suicide ideation and NSSI, and (c) the risk for suicide attempts (SA) across joint trajectories of suicide ideation and NSSI. Method: At baseline, 565 tenth-grade Chinese adolescents (48.3% males) reported depressive symptoms and friend support. Moreover, peer victimization and friendships were assessed using a sociometric procedure. After baseline, participants completed measures of suicide ideation, NSSI, and SA every 3 months for 2 years. Results: Three similar trajectories of suicide ideation and NSSI were identified. After accounting for depressive symptoms, peer victimization differentiated adolescents in the high trajectory of suicide ideation and NSSI from those in the low and moderate trajectories of suicide ideation and NSSI, respectively. Friend support and friendlessness distinguished between the high and low and the moderate and low NSSI trajectories, respectively. Joint trajectory models revealed a strong overlap between the course of suicide ideation and NSSI: Adolescents in the chronically high suicide ideation trajectory were at the highest risk to follow a chronically high NSSI trajectory and vice versa. Finally, adolescents in the joint chronically high trajectory were approximately 5 times more likely to report SA than were their peers, above and beyond prior SA. Conclusions: Findings highlight the role of negative peer experiences as risk factors for NSSI and suicide ideation, which, in turn, can potentially increase risk for SA.