Differential Associations between Two Characterizations of Impulsivity and Suicide Attempts and Lethality

Impulsivity is often implicated as a factor that facilitates the transition from suicidal thoughts to behaviors; however, findings to date are mixed as to whether this effect is direct or indirect through an increased acquired capability for suicide. These discrepancies may be due to heterogeneous conceptualization and operationalization of impulsivity. The present study aimed to clarify the nature of the relationship between impulsivity and suicidal behavior by investigating relationships between two characterizations of impulsivity—negative urgency and an inability to delay reward—and past number of suicide attempts and the medical lethality of those attempts. Participants (N = 167 undergraduate students, 80.2% female), aged 18 to 43 years (M = 19.31, SD = 2.64) completed measures of their negative urgency, ability to delay reward, and number of past suicide attempts, and were interviewed about the lethality of their past suicidal behavior. Results indicated that negative urgency had a direct association with past suicidal behavior; this was not accounted for by the acquired capability for suicide. Inability to delay reward was unrelated to suicide attempt frequency. Negative urgency, inability to delay reward, and acquired capability were unrelated to suicide attempt lethality. Overall, these findings suggest that a tendency to act rashly in the face of negative affect may lead to increased engagement in suicidal behavior, but not influence the lethality of that behavior, whereas an inability to delay reward may not be related to suicidal behavior. Future research should examine other characterizations of impulsivity in a variety of samples to better understand the nature of the relation between impulsivity and suicide.