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Director's Report to the National Advisory Council on Drug Abuse
February, 1995

Research Findings

Behavioral Research

Comprehensive Operant Behavioral Therapy for Treating Cocaine Addicts.

Cocaine abusers are hard to retain in treatment and difficult to treat successfully. However, Stephen Higgins and colleagues from the University of Vermont have developed a behavioral intervention that appears promising. The treatment program has four components: (1) quick detection of drug use based on frequent urine testing; (2) incentives (e.g., vouchers for pro-social items, positive reactions of counselors and significant others) or loss of incentives contingent upon urine testing results; (3) structured counseling sessions and (4) Disulfiram treatment for patients with substantial alcohol use. Drs. Higgins, Budney, and colleagues have reported on two trials comparing their behavioral treatment with "standard" drug treatment based on the 12-step disease model. The preliminary (non-random assignment) trial lasted for 12 weeks, and indicated that the behavioral treatment substantially and significantly retained patients in treatment better and engendered longer cocaine abstinence. The second trial randomly assigned 38 patients to the two groups and followed the patients for 24 weeks of treatment. As in the first trial, the behavioral treatment retained patients significantly longer than the standard 12-step treatment and resulted in greater abstinence. From both trials the behavioral treatment package appeared to be an effective intervention for retaining cocaine abusers in treatment and for establishing clinically significant abstinence.

Higgins and colleagues have also begun to investigate the therapy components. Forty cocaine addicts were randomly assigned to behavioral treatment with or without the voucher system. During weeks 1-12 one group received vouchers for cocaine-free urines while the other group received no vouchers. During weeks 13-24 the two groups were treated the same. The results showed that the vouchers contributed substantially to the outcome. Seventy-five percent of patients in the voucher group completed 24 weeks of treatment versus 40% in the no-voucher group. Continuous cocaine abstinence averaged 11.7 weeks in the voucher group versus 6.0 weeks in the no-voucher group. This study was a third replication demonstrating that the full behavioral treatment effectively retains cocaine-dependent patients in treatment and establishes significant periods of abstinence.

Most recently, Higgins and Budney have submitted a manuscript for publication describing a 12-month followup (i.e., after 6 months without treatment) of the patients in the two randomized trials. In comparing the full behavioral package with the 12-step disease model, Higgins and Budney found significantly greater cocaine abstinence at 12 months for the behavioral treatment-although both groups showed similar improvements on the Addiction Severity Index (ASI). In comparing the behavioral treatment with and without vouchers, they found that the voucher group showed more abstinence and used cocaine fewer days (nonsignificantly) and scored better on the ASI Drug Scale (significantly). Although the long-term followup suffered the usual complexities of patient dropout and attenuation of effects, the data continued to indicate greater efficacy of the behavioral treatment than for the comparison treatments.

The Economy of Drug Choices.

Studies being conducted by Dr. Stephen Higgins and Dr. Samuel Snodgrass at the University of Vermont are using models derived from economics to explore factors leading subjects to select alternative rewards to drug taking. For example, findings have shown that experienced cocaine users will prefer monetary rewards over intranasal cocaine for payments that are surprisingly small.

Animal studies at the University of Arkansas provide basic science support for these findings. Rats will prefer to ingest saccharine over cocaine if they are required to work substantially harder for a dose of cocaine. Alternative rewards to drug taking are of fundamental importance to the understanding and treatment of drug use and abuse.

Marijuana and Cognition.

Data from a recently completed NIDA-supported study show that long-term use of marijuana was associated with attentional deficit (selective attention, sustained attention, and/or divided attention) and difficulty with short-term memory tasks. The study was conducted in Costa Rican men of approximately 45 years of age who smoked marijuana for an average period of 8 years (4.9 marijuana cigarettes 2-7 times/week). There were two cohorts in the study: older cohort (42-45 years old) consisted of 23 users and 30 non-users of marijuana, and the younger cohort (27-30 years old) consisted of 61 users and 49 non-users of marijuana. These were assessed by Wechsler Adult Intelligence Scale, and various other sophisticated instruments to test for attentional and memory deficits. Results showed that chronic marijuana smoking was associated with attentional deficit (selective attention, sustained attention, and/or divided attention) and difficulty with short-term memory tasks in Costa Rican men (Fletcher, J., Adverse cognitive effects of chronic cannabis use, paper in preparation).
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