Abstinence-contingent reinforcement and engagement in non-drug-related activities among illicit drug abusers.

Methadone-maintained cocaine abusers (N = 78) were randomly assigned to 1 of the following 52-week interventions: (a) usual care only (UC), (b) take-home methadone doses contingent on cocaine- and opiate-negative results (THM), or (c) take-home methadone doses for cocaine- and opiate-negative results and monetary-based vouchers contingent on cocaine-negative urinalysis results (THM + V). Cocaine use was assessed by urinalysis on a thrice-weekly schedule. Frequency and enjoyability of non-drug-related activities were assessed with the Pleasant Events Schedule (PES) at baseline, midtreatment, and end of treatment. The THM + V condition achieved the greatest abstinence from cocaine and opiate use, followed by the THM and UC conditions. The THM + V condition had the highest PES frequency ratings at midtreatment and at the end of treatment, followed by the THM and UC conditions. There were significant differences between the THM + V and UC conditions on 10 of 12 PES-derived subscales. Analyses revealed that abstinence mediated the effects of treatment condition on frequency ratings. There were no significant differences in enjoyability ratings. These results suggest that when contingency-management interventions increase abstinence from drug abuse, they also increase engagement in non-drug-related activities in naturalistic settings.