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Project

Growing pains: Developmental trajectories of non-suicidal self-injury throughout adolescence in community and clinical samples

Non-suicidal self-injury (NSSI) refers to the deliberate, self-inflicted injury of body tissue (e.g., cutting, burning, or carving one’s own skin). NSSI is particularly prevalent in adolescence, with as many as 20% of community adolescents engaging in NSSI at least once. To provide a better understanding of NSSI in this at-risk age group, the current dissertation offers an in-depth examination of NSSI throughout adolescence. Specifically, we first investigated NSSI disorder, the recently proposed diagnosis aiming to capture severe and repetitive NSSI (Part I; Chapter 2 – 3). Then, we studied the stability, change, and maintaining factors of NSSI over the course of three years in adolescence (Part II; Chapter 4 – 5). Finally, we focused on NSSI in the vulnerable population of adolescents with an eating disorder (Part III; Chapter 6). The resulting six empirical chapters and their main findings are summarised below.

In Chapter 2, we investigated the prevalence of NSSI disorder (NSSI-D) in a large sample of community adolescents (N = 2130) and found NSSI-D to be particularly common in adolescent girls (11.7%), more so than in adolescent boys (2.9%). However, our results did raise concerns on the clinical utility and level of endorsement of some of the diagnostic criteria.
In Chapter 3, we addressed the distinctiveness of NSSI-D as a standalone diagnosis, specifically separate from Borderline Personality Disorder (BPD). We selected adolescents who engaged in NSSI at least once (N = 347) and found empirical support for NSSI-D as significantly distinct from, yet closely related to, BPD. Furthermore, loneliness, impulsivity, separation anxiety, frequent thinking about NSSI, and negative affect prior to NSSI were detected as prominent bridge symptoms connecting NSSI-D and BPD.
In Chapter 4, we investigated the stability and change of severity-based NSSI subgroups. In a longitudinal sample of community adolescents (at T1, N = 2162), our results indicated the presence of a large and stable no-NSSI subgroup, a small and unstable subthreshold-NSSI subgroup, and a small and moderately stable NSSI-D group. The transition from no-NSSI to subthreshold-NSSI could be predicted by identity confusion and trauma.
In Chapter 5, we then investigated which factors could maintain NSSI over time. In a longitudinal sample of community adolescents (at T1, n = 528), our analyses uncovered the mutual negative influence that NSSI, distress, and rumination exerted on one another. Specifically, a long-term maladaptive cycle emerged where distress and rumination increased the risk for later NSSI and NSSI increased the risk for later distress and rumination.
In Chapter 6, we confirmed the high prevalence of NSSI in inpatients adolescents diagnosed with an eating disorder (ED; N = 189). Moreover, in search of transdiagnostic mechanisms, we found that inpatients who engaged in NSSI showed significantly more harm avoidance and less self-directedness, irrespective of the subtype of ED that was diagnosed.

In sum, this dissertation highlights the high prevalence of NSSI in adolescence, yet emphasises that differentiation in terms of severity is crucial for a comprehensive assessment and adequate treatment of adolescent NSSI.

Date:1 Sep 2017 →  21 May 2021
Keywords:Non-suicidal self-injury, Adolescence, Identity development
Disciplines:Biological and physiological psychology, General psychology, Other psychology and cognitive sciences
Project type:PhD project