Social Mechanisms of Self-Harm in Adolescence

Self-harm is becoming increasingly prevalent and a major public health issue worldwide (Chan et al., 2016). Greater attention surrounds the adolescent population, who present a greater risk of engaging in such behaviours (Nock, 2010). In effect, self-harming acts have established themselves as the second most common cause of death in this age group (Hawton, Saunders & O'Connor, 2012).

The term self-harm is used to encompass intentional self-injurious acts and behaviours, now often classified as non-suicidal self-injury (NSSI) or deliberate self-harm with suicidal intent (NICE, 2013; Hamza, Stewart & Willoughby, 2012). Regardless of the present distinction, self-harm is nonetheless the highest risk factor leading to suicide (Kapur, Cooper, O'Connor & Hawton, 2013) as well as emotional, health-related and interpersonal difficulties (Mars et al., 2014). Thus, understanding the aetiology and mechanisms of self-harm may elucidate the best course of identification, treatment and support both for clinical and community populations.

Several models have emerged attempting to explain the causal mechanisms leading to such behaviours often including biological and genetic predispositions, environmental stressors, psychological factors and interpersonal issues (Hawton et al., 2012). Additionally, it has also been suggested that self-harm serves two main purposes: intrapersonal and interpersonal (Nock, 2010). The former leads individuals to engage in self-harming behaviours either to decrease negative emotions or to promote positive feelings; whereas the latter aims to acquire support or to remove undesirable social events. Whilst great research has been focused on unravelling the intrapersonal causes and functions of self-harm, the social environment promoting and maintaining these behaviours has often been overlooked (Prinstein et al., 2010). Particularly, little attention has been devoted to exploring the role of peers despite their greater influence during adolescence (Prinstein et al., 2010).

Recent evidence has explored several social mechanisms, which may function as risk and protective factors, encouraging or refraining young people from engaging in self-harming behaviours (Heilbron & Prinstein, 2008). First, experts point at direct transmission via social influence, often through the "social contagion" phenomenon, whereby exposure to a close relative or friend who self-harms may increase the risk of that individual also engaging in the same behaviour (Doyle, Sheridan & Treacy, 2015). On the other hand, indirect social influence effects may cause people to engage in self-injurious behaviours in order to imitate influential peers and to conform with the group norm, thus facilitating bonding (Young, Sproeber, Groschwitz, Preiss & Plener, 2014). Research has also suggested the opposite causal pathway to self-injury through social selection; for example, homophily whereby individuals befriend peers based on similarity in self-harm (Brechwald & Prinstein, 2011). Finally, a third variable or common stressors present in a group of individuals may also explain the presence of self-harm, without any social mechanisms exerting their influence (Prinstein et al., 2010).

This three-year PhD project will aim to investigate the changes in causes, motivations and triggers of self-harm over time, both in clinical and community populations of adolescents. The study will include both quantitative and qualitative accounts in order to explore both intrapersonal and interpersonal causes at the distal and proximal level. This approach will be complemented with an investigation of the role of social networks in influencing the trajectory of self-harm and recovery. Thus, a longitudinal Social Network analysis will be performed to observe the change in adolescents' peer network over three years and how that is associated with the course of their self-harming behaviours.