A comparison of delay discounting among substance users with and without suicide attempt history.

Although substance use disorders are associated with overall increased suicide risk, there is considerable variability in suicide risk among substance-dependent individuals (SDIs). Impairment in impulse control is common among SDIs, and it may contribute to vulnerability to suicidal behavior. The present study examined the relation between one specific aspect of impulsivity-delay discounting-and suicide attempt history in a sample of SDIs. An interaction was observed between suicide attempt history and discounting rates across delayed reward size. Specifically, SDIs with no history of attempted suicide, devalued small relative to large delayed rewards. In contrast, SDIs with a history of suicide attempts appeared comparatively indifferent to delayed reward size, discounting both small and large delayed rewards at essentially identical rates. These findings provide evidence that, despite the view that SDIs are characterized by marked difficulties in impulsivity, significant variability exists within this group in delay-discounting tendencies. Furthermore, these differences provide preliminary evidence that specific aspects of impulsivity may help to identify those most at risk for suicidal behavior in this population. The potential implications of our findings for suicide prevention efforts are discussed.