A longitudinal investigation of non-suicidal self-injury and perfectionism in a sample of New Zealand adolescents

Non-Suicidal Self-Injury (NSSI) is defined as the intentional, direct injury to body tissue, undertaken without suicidal intent, and for a purpose that is not socially or culturally sanctioned (International Society for the Study of Self-Injury, 2007; Klonsky & Muehlenkamp, 2007; Muehlenkamp, 2014). NSSI is prevalent in adolescent samples worldwide (Muehlenkamp, Claes, Havertape, & Plener, 2012; Swannell, Martin, Page, Hasking, & St John, 2014) and is typically considered a marker of wider distress. NSSI in adolescents has been associated with numerous poor mental health outcomes, including depression, anxiety, substance abuse, eating disorders, and attempted and completed suicide (Asarnow et al., 2011; Brunner et al., 2014; Claes, Soenens, Vansteenkiste, & Vandereycken, 2012; Fox et al., 2015; Glenn & Klonsky, 2011; Jacobson & Gould, 2007). In addition, research has demonstrated that perfectionism, defined as the setting of excessively high standards of performance (Frost, Marten, Lahart, & Rosenblate, 1990), is also commonly associated with substantial distress. Unfortunately, perfectionism in adolescents is thought to be on the rise (see Flett & Hewitt, 2014; Portesova & Urbanek, 2013) with many adolescents reporting multi-sourced and relentless pressure to perform highly and adhere to societal ideals. As such, individuals are setting excessively high goals for themselves, and increasingly worrying about the consequences of less than perfect performance. Similar to the research pertaining to NSSI, perfectionism has been shown to also be associated with a raft of poor outcomes including depression, anxiety, eating disorders, and general psychological distress (e.g., Boone, Braet, Vandereycken, & Claes, 2013; Claes et al., 2012; DiBartolo et al., 2007; Lombardo, Mallia, Battagliese, Grano, & Violani, 2013; Vartanian & Grisham, 2011). Research has shown an association between NSSI and perfectionism (e.g., Hoff & Muehlenkamp, 2009; O’Connor, Rasmussen, & Hawton, 2010). However, this literature is currently very limited and the relationship between NSSI and perfectionism is not well understood. In light of this, I set out to thoroughly explore if, and how, NSSI and perfectionism are related in New Zealand adolescents. Moreover, I aimed to gain insight into the mechanisms that could underpin such relationships. Of the four studies conducted, the first and second studies established a foundation for my research. Specifically, Study 1 meta-analyses synthesised data from 118 studies investigating the relationship between perfectionism and adaptive and maladaptive outcomes. These analyses demonstrated a robust relationship between negative perfectionism and maladaptive outcomes. More specifically, they revealed a significant, positive summary correlation for the relationship between negative perfectionism and self-injurious thoughts and behaviours. Study 2 aimed to define the most appropriate conceptualisation of perfectionism for research with New Zealand adolescents. This involved investigating the psychometric properties and factor structure of the Frost Multidimensional Perfectionism Scale (Frost et al., 1990) in 930 adolescents with a mean age of 14 years old. A hierarchical structure with two overarching components (positive perfectionism, negative perfectionism), comprised of four second-level components (concerns and doubts, parental pressure, personal standards, and organisation) was identified and adopted for all following research. Studies 3 and 4 investigated the cross-sectional and longitudinal relationships between NSSI and perfectionism. Study 3a specifically aimed to ascertain whether negative and positive perfectionism are associated with NSSI in New Zealand adolescents, based on survey data from 930 adolescents in their second year of high school. As expected, negative perfectionism was significantly associated with NSSI in females, however this relationship did not hold for males. On the other hand, positive perfectionism was associated with less engagement in NSSI in both males and females. This suggested that negative perfectionism may represent a risk factor for NSSI, while positive perfectionism may buffer against risk of NSSI. In addition, Study 3b investigated the relationships between perfectionism and the functions of NSSI, indicating that self-punishment functions are particularly relevant for perfectionistic adolescents. As the final component of the cross-sectional analyses, Study 3c illustrated that the association between perfectionism and NSSI is more accurately captured when the interaction between positive and negative perfectionism is also considered. Study 4 involved the examination of this relationship over time. To do so, another wave of data was collected, resulting in data matched across two times points for 608 adolescents. Longitudinal analyses demonstrated that negative perfectionism prospectively predicted NSSI one year later in females only. Moreover, again for only females, positive perfectionism predicted an increase in negative perfectionism over time. No significant longitudinal relationships were demonstrated for male adolescents. The ultimate aim of this research was to provide clinicians, school staff and parents with the information required to effectively identify at-risk adolescents, and thereby prevent the onset of NSSI and its vast associated negative outcomes. This research suggests that perfectionism is one such risk factor to be aware of. As such, it is argued that targeted prevention and intervention strategies for perfectionism will help prevent the onset and maintenance of NSSI in females, and are also likely to be of benefit to the wider mental wellbeing of New Zealand adolescents.