A Randomized Trial of Long-Term Reinforcement of Cocaine Abstinence in Methadone-Maintained Patients Who Inject Drugs.

This study determined whether long-term abstinence reinforcement could maintain cocaine abstinence throughout a yearlong period. Patients who injected drugs and used cocaine during methadone treatment (n = 78) were randomly assigned to 1 of 2 abstinence-reinforcement groups or to a usual care control group. Participants in the 2 abstinence-reinforcement groups could earn take-home methadone doses for providing opiate- and cocaine-free urine samples; participants in 1 of those groups also could earn $5,800 in vouchers for providing cocaine-free urine samples over 52 weeks. Both abstinence-reinforcement interventions increased cocaine abstinence, but the addition of the voucher intervention resulted in the largest and most sustained abstinence. Therefore, voucher-based reinforcement of cocaine abstinence in methadone patients can be a highly effective maintenance intervention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cocaine Abstinence During Methadone Maintenance: Effects of Repeated Brief Exposure to Voucher-Based Reinforcement.

This study determined whether abstinence engendered by intermittent reinforcement might generalize to nonreinforced periods and enhance overall rates of cocaine abstinence among methadone maintenance patients. Participants were randomized to 1 of 3 groups. The quantitative group (n = 14) earned incentives for a 50% decrease in urine benzoylecgonine concentrations; the qualitative group (n = 13) earned incentives for providing urines with concentrations     

Single- Versus Dual-Drug Target: Effects in a Brief Abstinence Incentive Procedure.

The number of drugs targeted may have an important influence on the ability of drug abusers to abstain during motivational incentive procedures. The authors investigated outcomes in methadone maintenance patients (n = 58), who had evidence of both opiate and cocaine use, when continuous abstinence from cocaine only (single target) or from both cocaine and heroin (dual target) was required to earn $200 in voucher incentives over a 4-day period. Study patients were equally likely to initiate and sustain abstinence from cocaine under the single- versus the dual-drug target. They were more likely to initiate opiate abstinence under the dual-target condition, demonstrating sensitivity to reinforcer effects. Results suggest that adding a second drug target does not impede short-term cocaine abstinence initiation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vocher-based reinforcement of opiate plus cocaine abstinence in treatment-resistant methadone patients: Effects of reinforcer magnitude.

The study tested a voucher-based abstinence reinforcement procedure for reducing opiate and cocaine use in a population of treatment-resistant opiate- and cocaine-abusing methadone patients. Vouchers exchangeable for goods and services were contingent on abstinence from both opiates and cocaine. In two conditions, participants could earn up to $374 or $3,369 in vouchers for providing opiate- and cocaine-free urine samples. Participants received a daily 60-mg dose of methadone. The dose was increased in a second phase, and the voucher conditions were replicated. Analyses of both phases revealed trends toward greater abstinence under the high voucher condition and suggested that higher doses may enhance the efficacy of voucher reinforcement. The results show that reinforcement for abstinence from 2 drugs simultaneously can be effective even in a treatment-resistant population. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contingency management in cocaine abusers: A dose-effect comparison of goods-based versus cash-based incentives.

Goods-based contingency management interventions (e.g., those using vouchers or prizes as incentives) have demonstrated efficacy in reducing cocaine use, but cost has limited dissemination to community clinics. Recent research suggests that development of a cash-based contingency management approach may improve treatment outcomes while reducing operational costs of the intervention. However, the clinical safety of providing cash-based incentives to substance abusers has been a concern. The present 16-week study compared the effects of goods-based versus cash-based incentives worth $0, $25, $50, and $100 on short-term cocaine abstinence in a small sample of cocaine-dependent methadone patients (N = 12). A within-subject design was used; a 9-day washout period separated each of 8 incentive conditions. Higher magnitude ($50 and $100) cash-based incentives (checks) produced greater cocaine abstinence compared with the control ($0) condition, but a magnitude effect was not seen for goods-based incentives (vouchers). A trend was observed for greater rates of abstinence in the cash-based versus goods-based incentives at the $50 and $100 magnitudes. Receipt of $100 checks did not increase subsequent rates of cocaine use above those seen in control conditions. The efficacy and safety data provided in this and other recent studies suggest that use of cash-based incentives deserves consideration for clinical applications of contingency management, but additional confirmation in research using larger samples and more prolonged periods of incentive delivery is needed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prize Reinforcement Contingency Management for Cocaine Dependence: Integration With Group Therapy in a Methadone Clinic.

In this study, the authors evaluated a low-cost contingency management (CM) procedure for reducing cocaine use and enhancing group therapy attendance in 77 cocaine-dependent methadone patients. Patients were randomly assigned to 12 weeks of standard treatment or standard treatment with CM, in which patients earned the opportunity to win prizes ranging from $1 to $100 for submitting cocainenegative samples and attending therapy. Patients in the CM condition submitted more cocaine-negative samples and attended more groups than patients in standard treatment. The best predictor of cocaine abstinence at follow-up was duration of abstinence during treatment. On average, patients in the CM condition earned $117 in prizes. Data from this study suggest that some aspects of reinforcement can be implemented in group therapy in community-based clinics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Shaping cocaine abstinence by successive approximation.

Cocaine-using methadone-maintenance patients were randomized to standard contingency management (abstinence group, n?=?49) or to a contingency designed to increase contact with reinforcers (shaping group, n?=?46). For 8 weeks, both groups earned escalating-value vouchers based on thrice-weekly urinalyses: The abstinence group earned vouchers for cocaine-negative urines only; the shaping group earned vouchers for each urine specimen with a 25% or more decrease in cocaine metabolite (first 3 weeks) and then for negative urines only (last 5 weeks). Cocaine use was lower in the shaping group, but only in the last 5 weeks, when the response requirement was identical. Thus, the shaping contingency appeared to better prepare patients for abstinence. A 2nd phase of the study showed that abstinence induced by escalating-value vouchers can be maintained by a nonescalating schedule, suggesting that contingency management can be practical as a maintenance treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Examining Interrelationships Between Abstinence and Coping Self-Efficacy in Cocaine-Dependent Outpatients.

Initial abstinence and self-efficacy predict treatment outcome in cocaine-dependent outpatients. Associations between abstinence and coping self-efficacy were examined among cocaine-dependent outpatients (N=126). Abstinence was verified by urinalysis. Coping self-efficacy was measured using a modified Situational Confidence Questionnaire (SCQ; H. M. Annis, 1984). The modified SCQ had good validity and reliability, and scores increased during treatment. In bivariate analyses, early abstinence and SCQ scores each predicted subsequent abstinence and confidence during treatment and posttreatment follow-up. Based on structural equation modeling, early confidence was a significant predictor of later confidence but not of later abstinence, whereas early abstinence was a significant predictor of later abstinence and confidence. Results suggest a unidirectional relationship wherein prior abstinence predicts subsequent abstinence and confidence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A randomized controlled trial of the therapeutic workplace for community methadone patients: A partial failure to engage.

The Therapeutic Workplace is an employment-based treatment for drug addiction that uses wages for work to reinforce drug abstinence. The Therapeutic Workplace has promoted abstinence from heroin and cocaine in treatment-resistant mothers in methadone treatment. This study attempted to replicate that effect in crack cocaine users recruited from community-based methadone programs. Participants were randomly assigned to a Therapeutic Workplace (n=22) or usual care control (n=25) group. Therapeutic Workplace participants were invited to work in the workplace and earn vouchers every weekday for 9 months contingent on documented opiate and cocaine abstinence. The two groups did not differ significantly on measures of cocaine or opiate use collected during study participation. Daily attendance and urinalysis results of the Therapeutic Workplace group were analyzed, and only 7 of the 22 participants initiated consistent periods of abstinence and workplace attendance. Two individuals gained access to the workplace on a few days, and 9 participants attempted to gain access to the workplace but never provided a drug-negative urine sample. Possible reasons for differences between the current study and the previous Therapeutic Workplace study are considered. Procedures that increase participant contact with the Therapeutic Workplace and its reinforcement contingencies might increase the likelihood of these individuals being successful in the treatment program. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The brief abstinence test: Effects of continued incentive availability on cocaine abstinence.

This study compared the effects of 4 voucher incentive conditions of a brief abstinence test on continuous cocaine abstinence. In 3 conditions, cocaine-abusing methadone patients could earn $100 for 2 days of cocaine abstinence; 2 of these conditions offered, on either a continuous or interrupted schedule, an additional $300 for evidence of sustained abstinence over the next 9 days. In the 4th condition, no incentives were available. In incentive conditions, 70-80% of patients initiated abstinence, compared with 48% in the no-incentive condition. Both continuing reinforcement conditions produced higher rates of sustained abstinence than the single and no-voucher conditions. The study confirmed the utility of quantitative urine-testing methods combined with high valued incentives to promote cocaine abstinence initiation in methadone maintenance patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Low-cost contingency management for treating cocaine- and opioid-abusing methadone patients.

This study evaluated the efficacy of a low-cost contingency management (CM) procedure in reducing concurrent cocaine and opioid use among methadone patients. Forty-two patients were randomly assigned to 12 wks of standard treatment or standard treatment plus CM. CM patients earned the opportunity to draw from a bowl and win prizes ranging from $1 to $100 in value for submitting samples negative for cocaine and opioids. Patients in the CM condition achieved longer durations of continuous abstinence than patients in the standard treatment condition, and these effects were maintained throughout a 6-mo follow-up period. On average, patients in the CM condition earned $137 of prizes. These data suggest that this prize reinforcement procedure may be suitable for community-based settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparable efficacy of contingency management for cocaine dependence among African American, Hispanic, and White methadone maintenance clients.

Cocaine use is a significant problem among methadone maintenance clients. Contingency management (CM) is a reinforcement-based approach with demonstrated efficacy for reducing cocaine use. This study examines whether the efficacy of CM treatment for cocaine-dependent individuals receiving methadone maintenance for opioid dependence differs by ethnicity. Participants were 191 African American, Hispanic, and White cocaine-dependent methadone maintenance clients, randomly assigned to standard methadone treatment or standard methadone treatment plus CM for 12 weeks. Hispanic participants were younger, less educated, and reported fewer years of cocaine use than did African American and White participants and reported fewer years of heroin use than did African American participants. African American participants were less likely to report a history of psychiatric symptoms or treatment in comparison with Hispanic and White participants. While CM was associated with longer duration of continuous cocaine abstinence and a greater proportion of submitted urine samples negative for cocaine, ethnicity was not related to treatment outcomes, and there was no significant interaction between treatment and ethnicity. CM appears to be an efficacious treatment for cocaine dependence among methadone maintenance clients, regardless of ethnicity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Randomized trial of contingent prizes versus vouchers in cocaine-using methadone patients.

Contingency management (CM) interventions frequently utilize vouchers as reinforcers, but a prize-based system is also efficacious. This study compared these approaches. Seventy-four cocaine-dependent methadone outpatients were randomly assigned to standard treatment (ST), ST plus a maximum of $585 in contingent vouchers, or ST plus an expected average maximum of $300 in contingent prizes for 12 weeks. CM participants achieved longer durations of abstinence (LDA) than ST participants, and CM conditions did not differ significantly in outcomes or amount of reinforcement earned. Although long-term abstinence did not differ by group, LDA during treatment was the best predictor of abstinence at 9 months. Thus, reinforcement with prizes was similar to voucher CM in promoting LDA, which is associated with posttreatment benefits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An Experimental Examination of the Initial Weeks of Abstinence in Cigarette Smokers.

Gaining experimental control over abstinence may help define processes that change during abstinence that may be related to the association between initial abstinence and relapse risk often noted in clinical trials. Adult smokers (n = 34) were randomly assigned to receive monetary incentives contingent on abstinence (CO ± 4 ppm) or noncontingent for 12 days. Carbon monoxide (CO) tests were conducted 3 times per day, saliva samples were collected on Days 5 and 12, and all other measures were collected 1 time per day. In the contingent group, 59% of participants abstained throughout the study versus 0% in the control condition. Abstinence was associated with increases in participant-rated ease of abstaining and confidence in abstinence; nicotine withdrawal severity and craving decreased over time. Results indicate that it is feasible to experimentally manipulate smoking abstinence and that doing so can enhance understanding of the relationship between early abstinence and relapse risk. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transitions During Effective Treatment for Cocaine-Abusing Homeless Persons: Establishing Abstinence, Lapse, and Relapse, and Reestablishing Abstinence.

Data are reported on drug use among cocaine-dependent homeless persons who participated in a clinical trial that compared day treatment only (DT, n = 69) with day treatment plus abstinent-contingent housing and work (DT+, n = 72). Drug use was measured with multiple weekly urine toxicologies. Compared with DT participants, more DT+ participants established abstinence, maintained abstinence for longer durations, were marginally significantly more likely to lapse, and significantly less likely to relapse. Of all participants who established abstinence and then relapsed, DT+ participants relapsed later and were more likely to reestablish abstinence. These analyses yield information on the processes involved in the manner in which drug use changes as a result of abstinent-contingent housing and work. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schedules of reinforcement as determinants of human causality judgments and response rates.

Experiments examined the effect of relationships between a response and an outcome on human judgments of causal effectiveness. In Experiment 1, the time between outcomes obtained on a variable ratio (VR) schedule became the intervals for a yoked variable interval (VI) schedule. Response rates were higher on the VR than on the VI schedule. In Experiment 2, the number of responses required per outcome on a VR schedule were matched to that on a master VI 20-s schedule. Both ratings of causal effectiveness and response rates were higher in the VR schedule. In Experiment 3, tandem VI fixed-ratio (FR) schedules produced higher rates and judgments than equivalent conjunctive VI FR schedule. In Experiment 4, a VI schedule with a reinforcement requirement for a short interresponse time (IRT) produced higher rates and judgments than a simple VI schedule. These results corroborate the view that schedules are a determinant of both response rates and causal judgments. Few current theories of causal judgment predict this pattern of results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Conditions for Temporal Tracking Under Interval Schedules of Reinforcement.

On many cyclic-interval schedules, animals adjust their postreinforcement pause to follow the interval duration (temporal tracking). Six pigeons were trained on a series of square-wave (2-valued) interval schedules (e.g., 12 fixed-interval [FI] 60, 4 FI 180). Experiment 1 showed that pigeons track square-wave schedules, except those with a single long interval per cycle. Experiments 2 and 3 established that tracking and nontracking are learned and both can transfer from one cyclic schedule to another. Experiment 4 demonstrated that pigeons track a schedule with a single short interval per cycle, suggesting that a dual process--cuing and tracking--is necessary to explain behavior on these schedules. These findings suggest a potential explanation for earlier results that reported a failure to track square-wave schedules. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned Activity and Instrumental Reinforcement Following Long-Term Oral Consumption of Cocaine by Rats.

Food-reinforced conditioned activity and instrumental responding were measured in rats after 50 weeks of continuous access to a cocaine-saccharin solution in their home cages. The elevation of conditioned activity produced by acute access to the cocaine-saccharin solution in the home cage during testing was abolished by long-term preexposure to the cocaine solution, an effect that was reversed by systemic administration of cocaine immediately prior to testing. By contrast, chronic cocaine preexposure enhanced instrumental responding for both cocaine-sucrose and pure sucrose solutions. These results support the idea that long-term cocaine exposure enhances subsequent reinforcement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive-behavioral therapy plus contingency management for cocaine use: Findings during treatment and across 12-month follow-up.

Contingency management (CM) rapidly reduces cocaine use, but its effects subside after treatment. Cognitive-behavioral therapy (CBT) produces reductions months after treatment. Combined, the 2 might be complementary. One hundred ninety-three cocaine-using methadone-maintained outpatients were randomly assigned to 12 weeks of group therapy (CBT or a control condition) and voucher availability (CM contingent on cocaine-negative urine or noncontingent). Follow-ups occurred 3, 6, and 12 months posttreatment. Primary outcome was cocaine-negative urine (urinalysis 3 times/week during treatment and once at each follow-up). During treatment, initial effects of CM were dampened by CBT. Posttreatment, there were signs of additive benefits, significant in 3- versus 12-month contrasts. Former CBT participants were also more likely to acknowledge cocaine use and its effects and to report employment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Participants Receiving Dehydroepiandrosterone During Treatment for Cocaine Dependence Show High Rates of Cocaine Use in a Placebo-Controlled Pilot Study.

Twenty-three cocaine-dependent participants were randomly assigned to receive either dehydroepiandrosterone (DHEA; n = 11; 100 mg/day) or placebo (n = 12) in the context of 12 weeks of thrice weekly cognitive-behavioral group counseling. Outcomes were retention, urine drug screening, cocaine craving, adverse experiences, and medication compliance. DHEA-treated participants averaged 45.8 (SD = 28.8) days in treatment, compared with 70.7 (SD = 20.6) days for placebo, r(21) = -2.4, p = .03, and provided 26.8% (SD = 29.3) of urine samples free of cocaine metabolite compared with 70.6% (SD = 39.9) for the placebo condition, r(21) = -3.0, p = .01. No differences were detected between conditions for cocaine craving or adverse experiences. High levels of medication compliance were documented. Results argue against using high doses of DHEA as a pharmacotherapy for cocaine dependence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)