Non-Suicidal Self Injury and Suicidal Behavior in College Students: Conditional Indirect Effects of Substance Abuse and Thwarted Interpersonal Needs

Non-suicidal self-injury (NSSI), or deliberate self-harm, and suicidal behaviors are significant public health concerns, and college students may be at particular risk. For instance, approximately 17% of college students engage in NSSI and suicide is the 2nd leading cause of death in college students. Commonalities between NSSI and suicidal behavior exist, including etiology; as an example, misuse of substances and interpersonal difficulties are related to both outcomes. For college students, substance use disorders and social dysfunction are two of the most common psychosocial problems; for instance, 22% of students report illicit drug use and social isolation, loneliness and separation from traditional support systems are common collegiate stressors. According to the Interpersonal Theory of Suicide, two pertinent interpersonal risk factors are perceived burdensomeness (the belief that one is a liability to others) and thwarted belongingness (the unmet need to belong among others). When present, substance misuse and interpersonal dysfunction may facilitate the transition between NSSI and suicidal behavior; however, this premise has not been previously examined. As such, we hypothesized that substance abuse would mediate the relation between NSSI and suicidal behavior, such that engagement in NSSI would be related to greater use of substances and, in turn, to suicidal behavior. Further, we hypothesized that thwarted interpersonal needs would moderate this mediating effect, such that increased TB and PB would exacerbate the mediating effect of substance misuse. Our sample of college students (N=338) was primarily white (89.6%; n=294), female (67%; n=225), and had an average age of 21.8 years (SD=4.7). Participants completed the Suicide Behaviors Questionnaire-Revised, the Self-Harm Inventory, the Interpersonal Needs Questionnaire, and the Drug Abuse Screening Test. Supporting hypotheses, substance abuse partially mediated the relationship between NSSI and suicidal behavior (DE=1.30, SE=.10, p