Michael D. Anestis, Kim L. Gratz, Courtney L. Bagge, Matthew T. Tull

The primary purpose of this study was to examine the interactive effect of borderline personality disorder (BPD) and distress tolerance (DT) on suicidal behavior across levels of intent to die (clear vs ambiguous) and medical severity. One hundred seventy-six adult patients in residential substance use disorder treatment were administered a series of structured interviews, behavioral assessments, and self-report questionnaires. A series of analyses of covariance and multiple regression analyses were conducted to test hypotheses using both categorical and dimensional measures of BPD and DT. Analyses supported hypotheses, indicating that patients with BPD who exhibit high DT are at the greatest risk for engaging in chronic and medically serious suicidal behavior. Although high DT is unlikely to be inherently problematic, results suggest that within the context of severe psychopathology (eg, co-occurring BPD-substance use disorder), the ability to withstand aversive internal states in pursuit of a goal (eg, one's own death) may enable individuals to persist in otherwise unsustainable behavior. In this sense, DT may function in a manner consistent with the acquired capability for suicide (a component of the interpersonal-psychological theory of suicidal behavior defined by a diminished fear of death and enhanced tolerance for pain that, in the presence of suicidal desire, enables individuals to enact lethal self-injury).