Improving Learning-based Treatment of Cocaine Dependence With Medication

Cocaine dependence is a public health problem with substantial morbidity, however no effective pharmacotherapy for cocaine dependence has been approved by the FDA. Unlike previous medication studies that have sought to pharmacologically reduce cocaine reinforcement, seeking or craving, this exploratory clinical trial will test d-cycloserine (DCS) for its ability to improve learning-based behavioral treatment of cocaine dependence. DCS is an NMDA partial agonist that has been shown to robustly improve learning in preclinical models, including extinction of cocaine conditioned place preference and blockade of cocaine reacquisition, and to improve extinction-learning based exposure therapy for multiple anxiety disorders. This Phase II clinical trial will investigate the pharmacological (DCS) enhancement of a behavioral treatment combining contingency management (CM) and novel home-environment exposure therapy sessions for cocaine dependence. High magnitude CM incentives will be used to promote the cocaine abstinence necessary for extinction in home-based exposure sessions. Participants will be randomized into 2 groups: 1. CM with placebo (CM+PL), and 2. CM with DCS (CM+DCS). For 19 days after group assignment, participants will report to the laboratory 3 times per week (Mon, Wed, Fri) to provide urine samples, receive contingent vouchers, and complete assessments of drug use, craving, mood, withdrawal, and quit self-efficacy. DCS (50 mg) or placebo will be administered on Mon, Wed and Fri study visits (at the end of the lab visit before returning to the home environment for exposure sessions during the time of DCS action). Follow-up visits will be conducted at 1 week, 1 month, and 3 months post-CM completion, during which time measures of drug use (self-reported and urinalysis), craving, mood, and withdrawal will be obtained. Comparison of continuous abstinence post-CM between the groups will be the primary outcome measure. During an initial laboratory session, a battery of learning/cognitive tasks will test for forms of learning/cognition enhanced by DCS that might contribute to the treatment effect. This project will test the efficacy of a novel intervention for cocaine dependence that was developed based on a known efficacious cocaine dependence treatment (CM), principles of extinction learning theory, and a medication shown to improve preclinical learning in general, including extinction of cocaine conditioning, and clinical learning-based exposure treatment of anxiety disorders. The study may indicate cost effective additions (home exposure sessions and DCS) to extend CM benefit after the removal of contingencies, and therefore may increase the dissemination of CM in community settings.