Nonsuicidal self-injury (NSSI) describes the direct, deliberate destruction of one’s own body tissue that is done without conscious suicidal intent and is not socially sanctioned within one’s culture. This behaviour poses a growing public health concern with research showing that NSSI is a marker for more severe psychopathology in the form of suicide attempts, depression, and anxiety as well as costs the Australian government over 14 million dollars each month in hospital admissions. Despite these adverse outcomes, there remains a lack of understanding regarding the course of this behaviour in terms of onset, continuation, and cessation to inform prevention and early intervention programs. To help address these central gaps in the literature, the main aims of the current thesis were to (a) explore prospective predictors of the onset of NSSI; (b) explore prospective predictors of the continuation of NSSI, including maintenance and progression over a one year period among school-based adolescents; and (c) explore young adults’ contextual experience of cessation to better understand how individuals stop self-injuring.
To prospectively explore risk factors related to the course of NSSI, self-report data were collected from 1,973 school-based adolescents (13 to 19 years old; M = 14.9, SD = 0.96) at two time points, one year apart. In line with psychosocial factors implicated in the theoretical and/or empirical research, the relationship between psychological distress (General Health Questionnaire - 12), emotion regulation (Emotion Regulation Questionnaire), coping (Adolescent Coping Scale - short form), social support (Multidimensional Scale of Perceived Social Support), self-esteem (Rosenberg Self-Esteem Scale), and NSSI (Self-Harm Behaviour Questionnaire) were explored, after controlling for relevant socio-demographic factors. Sequential logistic regressions as well as sequential multiple regressions were used, where appropriate, to explore predictors of onset and continuation. Multiple imputation analyses were used to assess the impact of missing data (<10%). Qualitative interviews, guided by interpretative phenomenological analysis, were used to explore how young adults with a history of NSSI make sense of their cessation in this behaviour. Specifically, six Caucasian female undergraduate college students aged 18 to 25 (M = 21.3, SD = 3.20) were interviewed.
Together, data suggest that in one year, about one-third of adolescents who reported NSSI started this behaviour (32%); one-third continued this behaviour from baseline (34%), and one-third had not engaged in this behaviour for more than 12 months (34%). Adolescents who continued to self-injure became more frequent with more serious wounds and an increased number of NSSI methods. Onset of NSSI was associated with being female (OR = 3.42, 95% CI [1.45, 8.06]); being born outside of Australia (OR = 1.73, 95% CI [0.79, 3.77], see imputed analyses); not identifying as religious or spiritual (OR = 1.83, 95% CI [1.06, 3.15]); higher psychological distress (OR = 1.12, 95% CI [1.08, 1.16]); poorer social support from family (OR = 0.90, 95% CI [0.84, 0.96]); and poorer self-esteem (OR = 0.90, 95% CI [0.82, 0.98]) at baseline relative to those who had never self-injured. Adolescents’ continuation of NSSI was associated with higher frequency of NSSI (OR = 1.06, 95% CI [0.99, 1.13]; see imputed analysis) and poorer cognitive reappraisal (OR = 0.88, 95% CI [0.80, 0.96]) at baseline relative to adolescents who stopped self-injuring. Most of the psychosocial factors that were examined did not relate to frequency, seriousness of wounds, and number of methods of NSSI among adolescents who continued this behaviour from baseline. Baseline measures of frequency (β = .48), seriousness of wounds (β = .59), and number of methods (β = .57) showed the strongest associations, respectively. With regard to experiential accounts of cessation of NSSI, six themes were found centring on gaining control, belonging and social support, development and use of adaptive coping strategies, goal-setting, realising the effect of NSSI on loved ones, and not wanting to identify as a self-injurer.
Overall, longitudinal findings support that there are prospective associations between psychological distress, emotion regulation, social support, and self-esteem in relation to NSSI; however, weak effects question whether these factors are theoretically meaningful. The different pattern of factors associated with onset and continuation suggest that models attempting to explain NSSI should convey the apparent complexity of factors related to this behaviour and how this course may change over time as individuals continue self-injuring. Qualitative data appears to highlight significant internal and external stressors possibly triggering a NSSI response but once resolved or better managed aid in cessation. The themes also highlight the importance of developing motivations to stop self-injuring and provide insight into how these motivations may be formed. Together, these findings may assist to better identify young people more likely to start and continue self-injuring as well as highlight issues to provide a focus for prevention and early intervention programs.