Treatment of Cocaine Dependence Through the Principles of Behavior Analysis and Behavioral Pharmacology

By Stephen T. Higgins and Alan J. Budney

INTRODUCTION

This report describes a series of prospective and retrospective studies conducted to examine the efficacy of an outpatient behavioral treatment for cocaine dependence (Budney et al. 1991; Higgins et al. 1991, 1993a, 1993b, in press-a).

The treatment is based on the scientific principles and conceptual framework of behavior analysis and behavioral pharmacology. In that framework, use of abused drugs is considered a special case of operant behavior that is maintained by the reinforcing effects of the drugs involved. Scientific support for this behavioral approach to drug abuse stems from the reliable empirical observation that laboratory animals self-administer most of the same drugs that are abused by humans (Griffiths et al. 1980; Henningfield et al. 1986).

Cocaine, amphetamines, opioids, sedatives, and ethanol are readily self-administered by laboratory animals (Young and Herling 1986). Neither a prior history of drug exposure nor physical dependence is necessary for these drugs to function as reinforcers and maintain an ongoing pattern of drug self-administration.

Effects of alterations in drug availability, drug dose, response requirement, and other environmental factors on drug ingestion are orderly and have generality across a variety of species, including humans, and different types of drug dependence (Griffiths et al. 1980). Such commonalities across species and types of drug dependence support a position that the fundamental causes of drug self-administration and dependence lie at the level of basic biologic processes common across many species (Brady 1981; Griffiths et al. 1980; Stitzer et al. 1989).

This behavioral model of drug abuse has permitted researchers to effectively extrapolate and apply to drug dependence scientific principles already available from research on other types of operant behavior and has generated a great deal of empirical knowledge concerning the dynamic role played by environmental and pharmacological variables in the reinforcing effects of drugs (Goldberg and Stolerman 1986). That knowledge has important treatment implications that are applicable to the treatment of cocaine dependence.

The basic strategy is to rearrange the drug user’s environment so that (1) drug use and abstinence are readily detected, (2) drug abstinence is positively reinforced, (3) drug use results in an immediate loss of reinforcement, and (4) the density of reinforcement derived from nondrug sources is increased to compete with the reinforcing effects of drugs.

A Behavioral Treatment for Cocaine Dependence

The behavioral treatment described in this report is 6 months in duration and implements the aforementioned strategy via contingencymanagement procedures (Bigelow et al. 1981; Stitzer et al. 1989) integrated with counseling from the Community Reinforcement Approach (CRA) (Sisson and Azrin 1989).

Detection of Drug Use.

In order to detect cocaine use and abstinence, urine specimens are collected under staff observation according to a fixed monitoring schedule (e.g., Monday, Wednesday, and Friday). Specimens are screened immediately with an onsite Enzyme Multiplied Immunoassay Technique (EMIT) (Syva Corp., Palo Alto, CA). All specimens are tested within several minutes after collection and screened for benzoylecgonine, a cocaine metabolite.

Failure to submit a scheduled specimen is treated as a cocaine-positive specimen. This fixed schedule of drug monitoring leaves little opportunity for undetected cocaine use. At least one randomly selected specimen each week also is screened for the presence of other abused drugs, and breath alcohol levels are assessed at the time urine specimens are collected. Abstinence Is Reinforced. Contingency-management procedures are used to reinforce cocaine abstinence.

Patients, therapists, and, when 98 possible, significant others are informed of urinalysis results immediately after testing. During weeks 1-12, specimens negative for benzoylecgonine earn points that are recorded on vouchers and given to patients.

Points are worth approximately $0.25 each. The first negative specimen is worth 10 points, or $2.50. The value of vouchers for each subsequent consecutive negative specimen increases by 5 points (e.g., the second voucher is worth 15 points, the third, 20 points, etc.)

To further increase the likelihood of continuous cocaine abstinence, the equivalent of a $10 bonus is earned for each three consecutive negative specimens. Submission of a cocainepositive specimen or failure to submit a scheduled specimen resets the value of vouchers to the initial $2.50 value, from which they can escalate again.

Submission of five consecutive cocaine-negative specimens following submission of a positive specimen returns the value of points to where they were prior to the reset. Points cannot be lost once earned. Money Is Never Provided Directly to Patients. Instead, vouchers are used to purchase retail items in the community. A staff member makes all purchases.

Items obtained using the vouchers are quite diverse and have included ski-lift passes, fishing licenses, gift certificates to local restaurants, camera equipment, bicycle equipment, and continuing education materials. Counselors retain veto power over all purchases.

Purchases are approved only if, in the counselor’s opinion, they are in concert with individual treatment goals of increasing drug-free prosocial activities. The voucher system is in effect during weeks 1-12 of treatment, while during weeks 13-24 the magnitude of the reinforcer is reduced to one Vermont State Lottery ticket for each cocaine-negative specimen.

Drug Use Results in the Loss of Positive Reinforcement

Vouchers, lottery tickets, and social reinforcement are withheld when urinalysis results indicate recent cocaine use.

Reinforcement Density From Nondrug Sources Increased.

The voucher system is designed to increase reinforcement density from nondrug sources, and aspects of CRA also are used for that purpose. The CRA procedures are implemented in twice-weekly, 1-hour counseling sessions for 12 weeks and then once weekly during the subsequent 12 weeks. 99 Sessions

Focus on Four General Issues. First, subjects with a spouse, friend, or relative who is not a drug abuser and is willing to participate in treatment receive reciprocal relationship counseling. This is a validated procedure for instructing dyads how to negotiate for positive changes in their relationship (Azrin et al. 1973).

To integrate CRA and contingency-management procedures, significant others are telephoned immediately following each urinalysis test and informed of results. If the specimen was negative for cocaine, the significant other engages in agreed-upon activities with the patient.

If the result was positive for cocaine use, the significant other refrains from the activities but offers assistance to the patient in dealing with difficulties in achieving abstinence. In recent trials, approximately 80 percent of patients have had a significant other participate in treatment at some point during the 6-month treatment period (Higgins et al. 1993a).

Significant others have included spouses or other sexual partners, parents, siblings, in-laws, and friends. No empirical evidence exists to indicate that any one type of significant other is better than another. Second, subjects are instructed how to recognize antecedents and consequences of their cocaine use.

They are counseled to restructure their daily activities to minimize contact with known antecedents, find alternatives for the positive consequences derived from cocaine use, and make explicit the negative consequences of cocaine use.

Skills training is provided to those with specific deficits (e.g., drug refusal, problem solving, or assertiveness). Patients exhibiting persistent evidence of depression are provided a behavioral treatment for depression that is easily integrated with this behavioral treatment for cocaine dependence.

Other problems that may interfere with achieving cocaine abstinence (e.g., persistent insomnia) also are addressed through behavioral counseling. Acquired immunodeficiency syndrome (AIDS) prevention counseling is provided to all patients.

Third, unemployed patients are offered employment counseling (Azrin and Besalel 1980). Assistance also is provided for those interested in pursuing educational goals or job changes and those with miscellaneous practical needs such as financial counseling, alternative housing, or legal and social services.

Fourth, subjects are counseled to develop new recreational activities or to become reinvolved in those they pursued prior to beginning cocaine use. Counselors and subjects work together to identify these activities. This also provides an avenue for integration of the contingencymanagement and CRA components. Vouchers earned through cocaine-free urine specimens are used to support costs of initiating these activities.

Treatment is delivered by master’s-level counselors specifically chosen because they are not trained in traditional approaches to drug and alcohol counseling. In the authors’ experience, it is difficult to find master’s-level counselors with experience in behavior therapy. To date, the authors have had success training rehabilitation counselors, general adult counselors, and graduate students in clinical psychology in this approach.

Clinical supervision is provided by a doctoral-level behavioral psychologist at least once weekly, and such close supervision by someone experienced in the use of behavioral treatments for substance abuse is necessary for effective application of this treatment approach. All patients who meet DSM III-R criteria for alcohol dependence or report that alcohol use causes problems in their attempts to achieve cocaine abstinence are offered disulfiram therapy.

Disulfiram therapy is an integral part of the CRA treatment for alcoholism (Sisson and Azrin 1989). The dose is usually 250 mg/daily unless patients report being able to consume alcohol at that dose without a reaction. In this case, the daily dose is increased to 500 mg. Disulfiram ingestion is observed by clinic staff when patients come for urinalysis monitoring. Take-home doses are provided for the other days and, if possible, are ingested in the presence of a significant other in accordance with disulfiram assurance procedures designed to improve compliance (Sisson and Azrin 1989).

RESEARCH STUDIES

Behavioral Treatment Versus Drug Abuse Counseling Nonrandomized Trial. The first study examining the efficacy of this behavioral treatment in establishing initial cocaine abstinence was 101 conducted with 13 consecutive admissions to an outpatient clinic (Higgins et al. 1991).

Results were compared against data from a second group of 15 consecutive admissions who received standard outpatient drug and alcohol counseling from a disease-model orientation. This study focused on the first 12 weeks of treatment. Urines were collected on Saturdays in addition to the Monday, Wednesday, and Friday schedule described above. Because the disulfiram component of the treatment was just beginning, only one patient in the behavioral group received disulfiram therapy.

Those in the drug abuse counseling group participated in the same schedule of urine monitoring as those in the behavioral treatment, but results were not shared with patients or therapists; patients received $5 per specimen independent of results.

The schedule of counseling was the same as in the behavioral group, but group therapy was emphasized consistent with the typical format in this approach. Patients were counseled that cocaine addiction was a treatable but incurable disease. They were requested to attend self-help meetings in addition to their regularly scheduled sessions. The regularly scheduled sessions consisted of both supportive and confrontive therapy, didactic lectures, and videos on cocaine dependence, AIDS, the disease model of addiction, and the self-help orientation.

Patients were expected to identify a sponsor from a local self-help group by week 12. Counseling was delivered by master’s-level counselors experienced in standard drug and alcohol counseling, and clinical supervision was provided by a master’s-level person with extensive experience in delivering and supervising this type of treatment.

To participate in the study, subjects had to be 18 years of age or older and meet DSM III-R criteria for cocaine dependence. The groups differed significantly on only two subject characteristics. Subjects in the behavioral treatment reported ingesting more cocaine per week (10.2 ± 8.6 g/week versus 3.7 ± 3.8 g/week) prior to entering treatment and had a significantly greater proportion of intravenous cocaine users (69 percent versus 17 percent) than the standard counseling group.

Acceptability of the behavioral treatment and drug abuse counseling to patients was inferred from the number who failed to attend more than one therapy session in the two groups. All who were offered the behavioral treatment accepted it, while 12 of 15 (80 percent) accepted 102 12-step counseling. Treatment retention was significantly better in the behavioral treatment than drug abuse counseling (p<0.05).

Eleven of the thirteen (85 percent) subjects in the behavioral treatment versus 5 of 12 (42 percent) in the drug and alcohol counseling group were retained for 12 weeks of counseling. Subjects from the behavioral treatment achieved significantly longer periods of continuous cocaine abstinence than subjects in the 12-step counseling group (p<0.01) (figure 1).

For example, 78 percent of the subjects in the behavioral group achieved 4 or more weeks of continuous cocaine abstinence versus 25 percent of the subjects in the counseling group. No members of the counseling group achieved more than 7 weeks of continuous cocaine abstinence, while 46 percent of the subjects in the behavioral group achieved 8 or more weeks of continuous cocaine abstinence, and 23 percent achieved 12 weeks.

-----
FIGURE 1. Periods of continuous cocaine abstinence in patients receiving behavioral treatment and drug and alcohol counseling. The height of each bar represents the percentage of patients (y-axis) achieving a duration of documented cocaine abstinence greater than or equal to the number of weeks indicated (x-axis). SOURCE: Higgins et al. 1991
--------

Randomized Trial. This initial trial comparing the behavioral treatment and standard drug and alcohol counseling was followed by a randomized trial comparing the same two treatments (Higgins et al. 1993a).

Thirty-eight patients were randomly assigned to the two treatments (19 per group). Patient characteristics did not differ significantly across the two treatment groups. Treatment duration was 6 months in both groups. The main differences from the initial trial were that urine specimens were not collected on Saturdays, treatment duration was increased from 3 to 6 months, and disulfiram therapy was available to both treatment groups.

Eight of the patients in the behavioral treatment group received disulfiram therapy at some point during the 24 weeks of treatment. Only one patient in the standard counseling group received disulfiram therapy, which is consistent with a common reluctance among traditionally trained drug abuse counselors to recommend disulfiram therapy.

One (5 percent) patient in the behavioral treatment versus eight (53 percent) in drug abuse counseling failed to attend more than one session (p = 0.02). Significantly more patients in the behavioral treatment than drug abuse counseling completed treatment (p<0.01). For example, 84 percent and 58 percent of those in the behavioral treatment completed 12 and 24 weeks of treatment, compared with 26 percent and 11 percent in drug abuse counseling.

When cocaine abstinence was analyzed as a function of consecutive treatment weeks, significantly larger numbers of patients in the behavioral group were abstinent during weeks 3-24 (p<0.05, figure 2, upper panel). Importantly, the incentives in the behavioral treatment were decreased in magnitude from the vouchers to lottery tickets at the end of week 12 without a precipitous decrease in cocaine abstinence (figure 2, upper panel).

Significant differences also were evident when continuous cocaine abstinence was compared (p = 0.005). For example, 68 percent and 42 percent of patients in the behavioral treatment achieved at least 8 and 16 weeks of documented continuous cocaine abstinence versus 11 percent and 5 percent in drug abuse counseling (figure 2, lower panel).

------
FIGURE 2. Upper panel: Percentage of patients (y-axis) in behavioral treatment and drug abuse counseling in whom cocaine abstinence was documented during consecutive weeks of treatment (x-axis). Lower panel: Periods of continuous cocaine abstinence in patients receiving behavioral treatment and drug and alcohol counseling. The height of each bar represents the percentage of patients (y-axis) achieving a duration of documented cocaine abstinence greater than or equal to the number of weeks indicated (x-axis). SOURCE: Higgins et al. 1993a
--------

This trial replicated the results from the nonrandomized trial, extended them to a longer treatment period, and demonstrated that treatment gains were maintained after the voucher system was discontinued. The consistency of the results observed across the two trials demonstrates the reliability of the effects of this behavioral treatment and strongly suggests that any outcome differences observed between this treatment and standard drug abuse counseling are not attributable to inadvertent differences in subject characteristics.

It merits mention that the difference between the two treatments in this trial in the number of patients who received disulfiram therapy cannot account for the outcome differences observed, as similar differences were observed in the earlier trial in which only one patient in the behavioral treatment group received disulfiram therapy. As is reported below, disulfiram therapy is associated with clinical improvement in this population, but it does not account for the large magnitude and reliable differences observed between the behavioral treatment and drug and alcohol counseling in these two trials.

The relatively poor outcomes observed with drug and alcohol counseling in these trials are comparable with those reported previously in outpatient counseling for cocaine dependence (e.g., Kang et al. 1991).
Randomized Trial Comparing the Behavioral Treatment With Versus Without the Voucher System It is not known at this time which components of this multicomponent behavioral intervention are contributing significantly to the outcomes observed. To begin to address that question, the authors currently are conducting a trial in which patients are randomly assigned to two groups.

One treatment group receives the entire behavioral treatment as described above, while the other group receives everything except the voucher system. Described below are reported preliminary results collected from 30 patients (15 per group) during the first 12 weeks of treatment, which is when the voucher system is in effect (Higgins et al. 1993a). There were no significant differences in subject characteristics between the treatment groups, and all subjects were 18 years of age or older and met DSM III-R criteria for cocaine dependence as in the prior trials.

The voucher system improved treatment retention, with 93 percent of those who received vouchers completing 12 weeks of treatment versus 106 67 percent of those who did not receive them. Those who received the vouchers also achieved greater levels of documented cocaine abstinence (figure 3).

For example, 67 percent of those who received vouchers achieved 6 or more weeks of documented continuous cocaine abstinence versus 40 percent of the group that did not receive vouchers.