Non-suicidal self-injury in adolescence and emerging adulthood: Role of identity formation in Belgium and India

Non-Suicidal Self-Injury (NSSI) is defined as the intentional and direct injuring of one's own body tissue without suicidal intent (Nock, 2009). Given that approximately 17.2% of adolescents and 13% of young adults report a history of NSSI (Swannell, Martin, Page, Hasking, & St John, 2014), it is being increasingly identified as an important mental health concern. Few studies to date have examined NSSI in relation to the core developmental task of adolescence, that is, identity formation. Additionally, insight in the prevalence and developmental associations of NSSI in non-Western countries (such as India) is still lacking (Gholamrezaei, De Stefano, & Heath, 2015). To address these gaps in the literature, the present PhD dissertation explored the association between NSSI and identity formation. We also investigated composite models combining antecedent factors (e.g., temperament, attachment) and identity formation and NSSI, to better understand NSSI. Finally, we also explored NSSI from a cross-cultural perspective.

               Chapter 1 briefly introduces the theoretical framework that grounds the present PhD dissertation and provides a short overview of the manuscripts included. Chapter 2 investigates the distribution of age of onset of NSSI in a pooled sample of Dutch-speaking adolescents and emerging adults. The findings of the study indicated that the probability of age of onset peaked around the age of 14-15 years in both community and psychiatric samples. A second peak was observed around the age of 20 and 24 years in the community and psychiatric samples, respectively. Chapter 3 examines the relation between NSSI and identity distress in specific domains. We found that adolescents engaging in NSSI showed higher distress in domains of long-term goals, friendship, sexual orientation and behavior, values and beliefs. Chapter 4 explores the directionality of effects between NSSI and identity synthesis/confusion using a longitudinal study design. Cross-lagged analyses indicated that associations between NSSI and identity synthesis and confusion are likely to be bi-directional. Chapter 5 tests if the association between temperamental traits and NSSI is mediated by identity synthesis/confusion. The main findings of the study were: effortful control moderated the pathway between Behavioral Inhibition System (BIS) and NSSI; and Identity synthesis mediated the pathway between BIS and NSSI. In Chapter 6, we investigate if identity synthesis/confusion mediated the association between dimensions of adolescents’ attachment with mother/peers and NSSI. Mediation analyses indicated that pathways between peer/maternal trust and maternal alienation and NSSI were fully mediated by both identity confusion and synthesis. The association between peer alienation and NSSI was partially mediated by a lack of identity synthesis.  Chapter 7 briefly reviews the existing NSSI research in India.  Chapter 8 presents findings of a cross-cultural comparison of NSSI and its relation to identity formation between India and Belgium. Age of onset, functions, and methods of NSSI differed between the two countries. Additionally, associations between NSSI and identity variables were found to be stronger in Belgium than in India.  Chapter 9 summarizes the key findings and also discusses the strengths and limitations as well as directions for future research. Finally, we also discuss clinical implications of our findings.