Nonsuicidal self-injury in adolescence: longitudinal course, trajectories, and intrapersonal predictors.

Although prevalence rates of nonsuicidal self-injury (NSSI) has been established throughout adolescence, little is known about the progression of NSSI, and consequently, about the risk factors for youth NSSI engagement. This study aimed to describe the overall longitudinal course of NSSI and the latent trajectory classes of NSSI in a population-based sample of adolescents using multi-wave data. Moreover, this study examined whether sex, lifetime history of depression, rumination, and negative attributional style predicted the longitudinal course of NSSI and trajectory group membership. Participants were 617 Chinese adolescents in Grades 10 through 12 (51.4 % girls). NSSI was assessed across eight waves of data. History of depression, rumination, and negative attributional style were assessed at baseline. Latent growth curve modeling revealed that only lifetime depression predicted the longitudinal course of NSSI from Grades 10 to 12, with depressed adolescents showing greater and more stable NSSI engagement over time than non-depressed adolescents. Group-based trajectory modeling yielded three distinct trajectory classes of NSSI engagement: low (69.2 %), moderate (26.1 %), and chronic (4.7 %). Negative attributional style distinguished adolescents in the chronic vs. low and moderate NSSI trajectory classes. Sex, rumination, and lifetime depression predicted membership in the chronic and/or moderate vs. low NSSI trajectory class. NSSI trajectory classes, based on frequency of NSSI, exist and are differentiated by sex, depression history, rumination, and negative attributional style. This study suggests that during this period of adolescence NSSI may be a relatively stable behavior, especially for some adolescents. Negative attributional style may be a salient risk factor for chronic NSSI engagement.