• 98 • New Zealand Journal of Psychology Vol. 46, No. 3, November 2017 Overview of assessment and treatment of non- suicidal self-injury among adolescents Jessica A. Garisch¹ , ², Marc S. Wilson¹, Angelique O’Connell¹ , ², Kealagh Robinson¹ ¹ Victoria University of Wellington, ² Child and Adolescent Mental Health Service, Capital and Coast District Health Board, New Zealand Non-Suicidal Self-Injury (NSSI) is the direct deliberate destrucon of bodily ssue, which is not socially sanconed, and occurs without suicidal intent. NSSI is a common behaviour among young people within Aotearoa New Zealand, and internaonally. About one-third to half of secondary school students have engaged in NSSI (Wilson et al., 2016; Garisch & Wilson, 2010), and whilst the figure among adolescents who aend mental health services in New Zealand remains unknown it is likely to be considerably higher. In spite of being a common behavioural concern among mental health clients, there is lile empirical research on effecve treatment. In parcular, there is a paucity of research into effecve treatment of adolescent NSSI; a gap that requires remedy given the high prevalence of NSSI and its associaon with many subsequent maladapve outcomes, including suicide. The current paper provides background informaon on NSSI, informaon on the assessment of NSSI such as what to include in an assessment interview and possible psychometric instruments, and outlines common strategies and challenges in treatment with adolescents. Keywords: NSSI, Self-Injury, Assessment, Treatment Non-suicidal self-injury (NSSI) is the direct, purposeful damage to body tissue, without suicidal intent. These behaviours are of low-lethality (e.g., cung), and are not condoned by a person’s cultural group. This arcle is intended as a summary of adolescent NSSI assessment and treatment, and is specifically written for a New Zealand audience, although other readers are likely to find the content useful. This arcle is intended for a broad range of readers, including school nurses, pastoral care staff, doctors, crisis workers, and mental health clinicians. Background to NSSI Prevalence Historically, there has been lile data on the prevalence of NSSI, with larger data sets only becoming available in the late 1990’s. Prevalence data prior to this me regarding self-injurious behaviour primarily drew from adult hospital admission rates (where only specific cases will present, as most people do not seek medical aenon for their self-injury (Baetens, Claes, Muehlenkamp, Grietens & Onghena, 2011)) and specific samples (i.e., the military). These prevalence rates were usually based on self-harm behaviour, rather than NSSI. Self-harm is a broader term inclusive of suicidal and non-suicidal self-harm behaviours, including self-poisoning. In this paper we discuss NSSI specifically. We use the term ‘NSSI’ and ‘self-injury’ interchangeably, for ease of readership. Adolescents appear at greatest risk of engaging in NSSI. This behaviour typically begins in early adolescence, with prevalence rates dropping sharply in early adulthood (Plener, Schumacher, Munz, & Groschwitz, 2015). Research indicates that a significant proporon of young people in New Zealand and internaonally engage in NSSI. Self-report survey studies conducted within the Wellington region indicate that between one fiſth and one quarter of community sample adolescents aged 12 – 15 have engaged in self-injury at some point (Wilson et al., 2016), with this figure increasing to up to 50% of adolescents by school leaving age (Garisch & Wilson, 2015). As may be expected, adolescents accessing mental health care appear to have higher prevalence rates of NSSI. Internaonal rates of NSSI among clinical adolescent samples indicate a prevalence of 40% or higher (DiClemente, Ponton, & Hartley, 1991). Within New Zealand clinical sengs, analysis of file informaon of clients within an Auckland-based Child and Adolescent Mental Health Service found that 48% of presenting adolescents reported lifetime engagement in deliberate self-harm (a broader term encapsulang both suicidal and non-suicidal self-harm; Fortune, Seymour & Lambie, 2005). However, it is important to bear in mind that as Fortune and colleagues’ (2005) study was based on analysis of file informaon, self-harm was not necessarily the presenng problem and therefore likely underesmates prevalence in this group. As such, rates of NSSI among adolescents in New Zealand mental health services remains unknown, however the prevalence is likely to be significantly higher than in community samples. Given this, many youth who present to services are likely to either have a history of NSSI or currently engage in the behaviour, making it an important part of assessment and treatment planning. NSSI and comorbid difficules NSSI is associated with many mental health problems including mood disorders, anxiety disorders, eang disorders, trichotillomania, and personality disorders (Jacobson & Gould, 2007; Nock, Joiner, Gordon, Lloyd-Richardson, & Prinstein, 2006), most notably borderline personality disorder (Brickman, Ammerman, Look, Berman & McCloskey, 2014). Some individuals who engage in NSSI will not have a diagnosable mental health disorder, whilst others will have mulple diagnoses (Wilkinson, 2013); presentaons of NSSI are highly heterogeneous. Research indicates that NSSI is associated with increased Jessica A. Garisch, Marc S. Wilson, Angelique O’Connell, et al.