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.
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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
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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).
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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
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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.
CONTINUOUS COCAINE ABSTINENCE
FIGURE 3. Periods of continuous cocaine abstinence in patients receiving-behavioral treatment with and without the voucher system. 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). KEY: CRA+ = Community Reinforcement Approach with vouchers; CRA- = Community
Reinforcement Approach without vouchers
Importantly, if the performance of the standard drug abuse counseling group from the prior randomized trial is used as a historical control, graded functions emerge. That is, levels of treatment retention and cocaine abstinence are best with the complete treatment package, intermediate with the behavioral treatment without vouchers, and lowest with standard counseling (figure 4).
When looked at in this manner, it seems that the voucher system contributes significantly to the efficacy of this behavioral treatment but other aspects of the treatment package are also important. The studies described below further support that position. Retrospective Analysis of Predictors of Cocaine Abstinence While the outcomes observed with the behavioral treatment package are impressive, not everyone responds equally well.
Thus, an investigation of predictors of who succeeded in the treatment was initiated. Towards that goal, a study was conducted using a stepwise logistic regression to identify significant predictors of cocaine abstinence during the initial 12 weeks of treatment in 52 patients who received the behavioral treatment (Higgins et al., in press-b).
Subjects were classified as “successes” and “failures” based upon their longest period of cocaine abstinence and the overall percentage of cocainenegative urine specimens submitted. Success was defined as having achieved 9 or more weeks of continuous abstinence or greater than 92 percent overall cocaine abstinence during the initial 12 weeks of treatment.
Subjects not meeting either of those criteria were classified as failures. The following variables were examined: age, gender, years of education, employment status, weekly income, years of regular cocaine use, average amount spent weekly on cocaine, average number of grams of cocaine used weekly, longest period of pretreatment cocaine abstinence since becoming a regular user, alcohol dependence, marijuana dependence, Addiction Severity Index (ASI) composite scores, and whether a subject had a significant other participate in treatment.
Using these abstinence criteria, 28 subjects were classified as successes and 24 as failures. The only significant predictor of success was
TREATMENT RETENTION CONTINUOUS COCAINE ABSTINENCE FIGURE 4. Upper panel: The percentage of patients who completed 12 weeks of treatment in the behavioral treatment with and without the voucher system and a historical control group that received drug and alcohol counseling. Lower panel: Periods of continuous cocaine abstinence in patients receiving the same treatments shown in the upper panel. 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). KEY: CRA+ = with Community Reinforcement Approach with vouchers; CRA- = Community Reinforcement Approach without vouchers; STD = Historical control group having a significant other participate in treatment.
Subjects who had a significant other participate in treatment were estimated to be almost 20 times as likely to achieve criterion levels of abstinence as those without a significant other participating in treatment. Having a significant other participate in treatment was a robust predictor of abstinence in this study. To the authors’ knowledge, this is the first study on predictors of treatment outcome in cocaine dependence to note a relationship between significant other involvement in treatment and cocaine abstinence.
Although it must be documented in a prospective randomized trial, reciprocal relationship counseling may contribute significantly to the positive treatment outcomes observed with this multicomponent behavioral treatment. Disulfiram Therapy in Patients Abusing Cocaine and Alcohol As noted above, disulfiram therapy is a component of this behavioral treatment approach and is offered to all patients who, in addition to cocaine dependence, report evidence of concurrent alcohol dependence or abuse. In this study, the authors attempted to assess for significant clinical changes associated with that therapy (Higgins et al. 1993b).
To do so, results were examined from 16 patients who met DSM III-R criteria for cocaine dependence and alcohol abuse/dependence. Subjects were chosen on the basis of having 2 or more weeks on and off disulfiram therapy, which provided an opportunity to assess for associated benefits. Because patients often determined when disulfiram therapy was terminated, causality for any changes observed could not be determined. The average durations on and off disulfiram therapy were 69.5 days ± 11.9 S.E.M. and 93.4 days ± 10.7.
The off-disulfiram period preceded the on period in 10 patients and followed it in 6 others. Patients reported to the clinic two or three times weekly and ingested disulfiram under staff supervision. Breath and urine specimens were collected under staff observation during those visits. Take-home doses of disulfiram were provided for the other days.
Other than the attempts to supervise ingestion, disulfiram therapy was provided using standard procedures (Puller et al. 1986). Patients generally ingested a single 250 mg/daily dose. Disulfiram therapy was associated with significant decreases in measures of drinking and cocaine use (figure 5). Patients reported an average of 0.05 ± 0.02 drinking days weekly while taking disulfiram versus 1.5 ± 0.4 off the medication (p = 0.001).
The average number of drinks per drinking occasion while taking disulfiram was 4.7 ± 2.2 versus 10.9 ± 2.6 off the medication. The frequency of cocaine use was already suppressed due to the efficacy of the behavioral treatment patients were receiving. Nevertheless, the percentage of cocaine positive specimens while taking disulfiram was 11 percent ± 3 versus 25 percent ± 6 off the medication (p = 0.01). In summary, supervised disulfiram therapy was associated with significant decreases in alcohol and cocaine use.
Controlled trials will be necessary to evaluate adequately the direct contribution of disulfiram therapy to these outcomes. Considering the large proportion of cocaine abusers who abuse alcohol, such trials merit serious consideration. It appears that in that subset of patients who are also alcohol abusers, including the disulfiram component may contribute significantly to the positive outcomes observed with this behavioral treatment package.
Contingency-Management Procedures in Patients Abusing Cocaine and Marijuana
This study examined the efficacy of the voucher system for controlling cocaine and marijuana use by multiple-drug abusers (Budney et al. 1991). Subjects were two males who received the behavioral treatment described above. Both were cocaine dependent; S-l also met criteria for marijuana dependence, while S-2 met criteria for marijuana abuse.
Both subjects achieved almost complete cocaine abstinence but continued regular marijuana use during the 12 weeks in which vouchers were available contingent on cocaine abstinence (figure 6, cocaine-abstinence phase). In a subsequent phase, reinforcement magnitude was reduced to $1 lottery tickets delivered contingent on submission of cocaine-free urine specimens. Weekly l-hour behavior therapy sessions were continued during this period, and urine specimens were collected twice weekly (Monday and Thursday).
ALCOHOL USE ON vs. OFF DISULFIRAM COCAINE USE ON vs. OFF DILSUFIRAM FIGURE 5. Upper panels: Self-reported average number of alcoholic drinks per week and self-reported average number of drinks per drinking occasion. Lower panel: Average percent cocaine-positive urinalysis results while on and off disulfiram therapy. Brackets represent ± 1 S.E.M.
During this period, both subjects maintained the patterns of cocaine abstinence and regular marijuana use exhibited in the initial phase (figure 6, cocaine-maintenance phase). Next, these individuals were given a 2-week notice that the reinforcement program conducted in the initial phase would be available for another 12 weeks but that points were now contingent on both cocaine and marijuana abstinence. Delivery of the notice to the individual subjects was staggered across time in the tradition of a multiple-baseline research design (Baer et al. 1968).
Schedules of urine monitoring and therapy remained as in the second phase. The overall value of vouchers that could be earned during the 12 weeks of this third phase was the same as in the initial phase. During this third phase, S-l and S-2 provided 96 percent (23 of 24) and 100 percent (24 of 24) negative benzoylecgonine and cannabinoid urine specimens (figure 6, cocaine-marijuana-abstinence phase). The temporal order of the change in urinalysis results across the two subjects coincided with the staggered intervention times, strongly suggesting that the changed contingencies controlled the changes in marijuana use.
At followup visits scheduled at 1 and 5 months after treatment termination, both subjects remained cocaine abstinent but had resumed marijuana use. Interestingly, both subjects deemed cocaine use a serious problem and requested treatment for it but did not deem marijuana use a problem. The present results demonstrate that abstinence from both substances can be achieved by arranging the reinforcement contingencies appropriately, but treatment gains made with the substance not deemed by patients as problematic may be relatively transient.
DISCUSSION
This behavioral treatment is very acceptable to patients. The vast majority (98 percent) of individuals who have been offered the treatment have accepted. Treatment acceptability to dependent individuals is important, especially because many of the individuals treated thus far were intravenous users at risk for contracting and spreading AIDS and other diseases (Chaisson et al. 1989). Current pharmacotherapies often are rejected by 30 percent or more of those offered treatment (e.g., Gawin et al. 1989; Weddington et al. 1991),
FIGURE 6. The cumulative number of negative cocaine and marijuana urinalysis results obtained during three phases of treatment are shown as a function of consecutive urinalysis tests conducted throughout treatment. Cocaine and marijuana are represented by closed and open symbols, respectively. SOURCE: Budney et al. 1991 and behavioral therapies with aversive contingencies are rejected by as many as 50 percent of patients (Anker and Crowley 1982).
Thus, this treatment may be more acceptable to patients than alternative pharmacological and psychological therapies. The treatment is effective in retaining patients in treatment. Across the trials conducted to date, more than 85 percent of patients have completed 12 or more weeks of treatment. The same issues that underscore the importance of treatment acceptability apply to treatment retention. As long as the individual remains in treatment, opportunities exist to facilitate behavior change. Longer stays in drug abuse treatment are associated with improved outcomes (e.g., Anglin and McGlothlin 1984), and once patients exit treatment, all opportunities to influence any aspect of their characteristically high-risk behavioral repertoires are lost.
The behavioral treatment is effective in establishing initial cocaine abstinence, as this has now been replicated in several trials (Higgins et al. 1991, 1993a). The obvious challenge is to address questions of longer-term abstinence and the generality of these findings to other clinics and populations. The 6-month randomized trial described above was a first step towards addressing the challenge of longer term abstinence, and the findings were encouraging (Higgins et al. 1993a).
Clinically significant periods of continuous cocaine abstinence were engendered in the majority of patients, and, at the end of 3 months of treatment, patients could be transitioned from the voucher system to the lower magnitude lottery tickets without a precipitous drop in cocaine abstinence levels. With regard to the issue of generality to other settings, several clinics located in large urban areas plan to examine the efficacy of either particular components of this treatment or the entire package. Thus, information regarding the generality of this treatment approach to other settings should be forthcoming.
This treatment can be adapted to address the high levels of alcohol and marijuana abuse common among cocaine-dependent individuals. Because the majority of cocaine-dependent persons also abuse these other drugs, any effective treatment for cocaine dependence must be able to address these other forms of drug abuse as well. The results observed with disulfiram therapy suggest that addressing alcohol abuse in this population is associated not only with significant decreases in alcohol consumption but also with significant decreases in cocaine use (Higgins et al. 1993b). Considering that almost all cocaine-dependent individuals use alcohol and the majority do so in an abusive manner, this could be a very important observation (Grant and Harford 1990).
Controlled trials examining the efficacy of disulfiram in the treatment of cocaine dependence are needed. The information provided above on marijuana use suggests that some individuals can use regularly without it adversely affecting cocaine abstinence. Marijuana use in those subjects is readily modifiable by means of a direct contingency-management intervention, although such changes appear to dissipate when the contingency is removed.
More information is needed on the influence of marijuana use on efforts to achieve cocaine abstinence so that clinicians can make informed decisions about how to address use of that substance during treatment for cocaine dependence. An important feature of this treatment approach is its direct ties to basic research in behavioral pharmacology and behavior analysis. As was noted above, this treatment is conceptualized and structured in terms of the basic principles and concepts of those scientific disciplines.
Operating according to a common set of concepts and principles in the basic research and clinical domains should support effective communication between those settings and facilitate a scientific approach to the treatment and prevention of drug dependence. The preliminary results of the trial comparing the behavioral treatment with and without the voucher system indicate that including it improves treatment retention and cocaine abstinence.
Although the costs of such a voucher system (maximum of $11-$12 per day across 3 months) may seem prohibitive at first blush, they pale, for example, in comparison to those incurred with the typical 28-day inpatient hospitalization for substance abuse or the costs incurred in caring for an individual who has contracted AIDS (Holder and Blose 1991; Drucker 1986).
Additionally, it is important that the behavioral processes involved in the treatment described in this chapter receive attention, not just the nature of the incentives used. This intervention illustrates the potential utility of frequent, contingent use of positive reinforcement in the treatment of cocaine dependence. It is possible 116 that the nature of the reinforcers used could be quite varied (i.e., one should not assume that vouchers redeemable for retail items are a necessary feature).
Also, if they are necessary, clinics may consider creative and cost-effective strategies for providing them. For example, nonprofit clinics may consider petitioning community retailers to donate items to be used as incentives. Use of access to community athletic facilities or other community resources is another possibility.
Results from the retrospective analysis of predictors of cocaine abstinence in this behavioral treatment strongly suggest that social reinforcers delivered systematically by significant others may play a significant role in establishing cocaine abstinence (Higgins et al., in press-b).
Although those findings need to be documented in a prospective, randomized trial, they illustrate the varied ways in which differential reinforcement procedures can be applied in trying to engender and maintain cocaine abstinence. Overall, the findings reviewed in this report illustrate that systematic application of basic behavioral concepts and principles can play an important role in effective treatment for cocaine and other forms of drug dependence.
NOTE This chapter is based in part on the brief review published previously (Higgins et al., in press-a).
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ACKNOWLEDGMENTS
This research was supported by USPHS Treatment Research Demonstration Grant R18 DA06113 and Training Grant T32 DA07242 from the National Institute on Drug Abuse. We acknowledge G. Badger, M.S., for assistance with statistical analyses and W.K. Bickel, Ph.D., and J.R. Hughes, M.D., for their scientific contributions to the research described in this chapter.
AUTHORS
Stephen T. Higgins, Ph.D. Associate Professor of Psychiatry and Psychology Department of Psychiatry and Psychology and Human Behavioral Pharmacology Laboratory
Alan J. Budney, Ph.D. Postdoctoral Fellow Department of Psychiatry and Human Behavioral Pharmacology Laboratory University of Vermont 38 Fletcher Place, Ira Allen School Burlington, VT 05401
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From NIDA Research Monograph 137 Behavioral Treatments for Drug Abuse and Dependence [pdf with multiple chapters, diagrams]