Psychosocial correlates of non-suicidal self-injury and firesetting among school-based adolescents

Adolescence marks a period of increased vulnerability for the development of high-risk or problem behaviors, with these behaviors often observed to co-occur among youth. Nonsuicidal self-injury (NSSI) and firesetting are two distinct variants of problem behavior representing significant public health concerns. While existing research examining cooccurring NSSI and firesetting indicates that these behaviors may be functionally related, most of these studies have been conducted within adult correctional or psychiatric facilities. Further, many risk factors associated with these behaviors independently have been implicated as determinants of a wide range of problem behaviors, limiting their predictive utility. Thus, the overarching objective of the present thesis was to examine the relative importance of a range of psychosocial variables to adolescent NSSI and/or firesetting, and determine how these variables increase the risk of suicidality (i.e., suicidal ideation and attempt) among youth with joint histories of NSSI and firesetting. Specifically, the three empirical studies comprising this thesis aimed to: (1) identify shared and unique risk factors of NSSI and firesetting, as independent behaviors, and to establish the prevalence and predictors of co-occurring NSSI and firesetting; (2) describe a high-risk cohort of schoolbased adolescents reporting co-morbid NSSI and firesetting, and compare psychosocial features of these adolescents to those engaging in either behavior alone; and (3) examine differences in psychosocial characteristics across varying levels of suicidality among this high-risk subgroup. To achieve these aims, self-report data were collected from a large cohort of schoolbased adolescents across Australia (n = 2673). The focus of investigation progressed across the empirical studies from this initial sample, to an at-risk subgroup of adolescents engaging in either NSSI and/or firesetting (n = 380) and finally, to a high-risk subgroup of youth engaging in both NSSI and firesetting (n = 77). Multivariate analyses were used to explore the relationships between psychosocial variables, problem behaviors (i.e., NSSI and/or firesetting), and suicidal ideation and attempt. Psychosocial variables of interest spanned socio-demographic (e.g., age, gender), environmental (e.g., negative life events, social support) and individual-level domains (e.g., mental health, coping and emotion regulation processes). Collectively, general vulnerabilities such as negative life experiences and coping deficits appear to increase the likelihood that adolescents will engage in a range of problem behaviors (i.e., NSSI and firesetting), with additional factors driving the selection of specific behaviors in the context of elevated risk. Specifically, self-critical and ruminative tendencies are especially relevant to NSSI, while socio-demographic and impulsivity-related traits are associated with firesetting. Adolescents engaging in both NSSI and firesetting appear to be a high-risk subgroup of youth with marked psychosocial impairments, including high rates of mental health problems, substance use, and exposure to multiple life stressors in the absence of adaptive coping strategies. These adolescents exhibit greater dysfunction and engage in more severe NSSI and firesetting than those engaging in either behavior alone. Notably, rates of suicidal ideation and attempt are markedly elevated among this group (60% and 20%, respectively), with the presence of firesetting doubling the likelihood that self-injurers consider or attempt suicide. Increasing levels of suicidality appear related to coping deficits, exposure to painful experiences, and a lack of self-efficacy regarding ability to manage distress. Findings highlight the importance of screening for additional behaviors and suicidality when an adolescent is identified as engaging in a problem behavior, and can further inform the development of interventions with youth engaging in multiple problem behaviors