Frequency and functions of non-suicidal self-injury: associations with suicidal thoughts and behaviors.

Previous research has found associations between non-suicidal self-injury (NSSI) and suicidal thoughts and behaviors (STBs), yet the nature of this relationship remains equivocal. The goal of the present study was to examine how lifetime NSSI frequency and individual NSSI functions relate to a history of suicidal ideation, plan, and attempt. Data were collected via a large (N=13,396) web-based survey of university students between the ages of 18 and 29. After demographics and psychiatric conditions were controlled for, we found a positive curvilinear relationship between NSSI frequency and each of the suicide outcomes. When examined among those with STBs, bipolar disorder and problematic substance use remained positively associated with risk for suicide attempt, but not NSSI. Analyses of individual NSSI functions showed differential associations with STBs of varying severity. Specifically, nearly every NSSI function was significantly related to suicide attempt, with functions related to avoiding committing suicide, coping with self-hatred, and feeling generation (anti-dissociation) showing the strongest risks for suicide attempt. From both clinical and research perspectives, these findings suggest the importance of assessing multiple reasons for engaging in self-injury.