The mediating role of non-suicidal self-injury in the relationship between impulsivity and suicidal behavior among inpatients receiving treatment for substance use disorders

Several theories posit a direct role of impulsivity in suicidal behavior. The interpersonal-psychological theory of suicidal behavior (IPTS) argues that the relationship between impulsivity and suicidal behavior is explained by the painful and/or provocative experiences (PPEs) often encountered by impulsive individuals. It thus seems plausible that nonsuicidal self-injury (NSSI), itself associated with impulsivity, might account for the relationship between impulsivity and suicidal behavior. We examined data from 93 adult inpatients (54.8% male) seeking treatment for substance use disorders. Patients completed a structured interview assessing prior suicidal behavior and a series of self-report questionnaires examining impulsivity, NSSI, and psychopathology. Four impulsivity dimensions (negative urgency, positive urgency, lack of premeditation, lack of perseverance) were associated with lifetime number of suicide attempts and/or suicide potential. Furthermore, results supported our hypotheses, as all but one relation was better accounted for by NSSI and, in the one exception, the direct effect was non-significant. Findings are consistent with the IPTS and suggest that suicidal behavior may not be a direct manifestation of impulsivity, but facilitated through exposure to PPEs capable of altering an individual's relationship to pain and fear of death.