Non-suicidal self-injury and frequency of suicide attempts: The role of pain persistence

Background: Non-suicidal self-injury (NSSI) and suicidal behavior exhibit a robust association with one another. Research on the contexts within which this relationship is stronger or weaker, however, is limited. The interpersonal theory of suicidal behavior (ITS) posits that NSSI influences suicidal behavior through a habituation to physical pain and, as such, pain tolerance has been theorized to play an important role. We tested whether pain persistence, the difference between pain threshold and pain tolerance, would moderate the relationship between frequency of NSSI and suicidal behavior in both an undergraduate and community sample. Method: Study 1 assessed healthy undergraduates, whereas Study 2 was comprised of community members recruited largely based upon a history of suicidal behavior. Across both samples, participants completed self report measures of NSSI and a structured interview on suicidal behavior. In both studies, pain was measured using a pressure algometer and, in Study 2, persistence was also assessed using the Enhanced Distress Tolerance Test (DTT-E). Results: Consistent with the notion that suicidal behavior requires persistence amidst pain and distress, results indicated that the willingness to remain engaged with pain and distress may significantly influence the degree to which NSSI is related to suicidal behavior. Limitations: Both studies were limited by a cross-sectional design, which precluded assessments of causality and directionally of effects. Conclusions: These results call attention to the potential importance of persistence through pain and/or distress in the association between NSSI and suicidal behavior.