Treating Adult Marijuana Dependence: A Test of the Relapse Prevention Model

Transcription

1 Journal of Consulting and Clinical Psychology 1994, Vol. 62, No. 1,92-99 Copyright 1994 by the American Psychological Association, Inc X/94/S3.00 Treating Adult Marijuana Dependence: A Test of the Relapse Prevention Model Robert S. Stephens, Roger A. Roffman, and Edith E. Simpson Men («= 161) and women (n = 51) seeking treatment for marijuana use were randomly assigned to either a relapse prevention (RP; G. A. Marlatt & J. R. Gordon, 1985) or a social support (SSP) group discussion intervention. Data collected for 12 months posttreatment revealed substantial reductions in frequency of marijuana use and associated problems. There were no significant differences between the cognitive-behavioral RP intervention and the SSP group discussion conditions on measures of days of marijuana use, related problems, or abstinence rates. Men in the RP condition were more likely than men in the SSP condition to report reduced use without problems at 3-month follow-up. Posttreatment increases in problems associated with alcohol did not appear to relate to reduced marijuana use. Results are discussed in terms of the need for further research with marijuanadependent adults and the efficacy of RP. Marijuana remains the most frequently used illicit drug in the United States, with over 5.5 million individuals reporting regular weekly use (National Institute on Drug Abuse, 1991). Epidemiological data on the prevalence of marijuana abuse and dependence are lacking, but studies of self-identified adult marijuana users in three different communities revealed substantial subsamples of users reporting impairment of memory, concentration, motivation, self-esteem, interpersonal relationships, health, employment, and finances related to their use of marijuana (Haas & Hendin, 1987; Rainone, Deren, Kleinman, & Wish, 1987; Roffman & Barnhart, 1987). Most users in these studies were not abusing alcohol or other drugs. Although a significant number of adults appear to be experiencing adverse social, health, and safety effects related to marijuana use (Negrete, 1988), there is almost no empirical literature on the treatment of marijuana-related problems. Many subjects reported an interest in treatment aimed at cessation of use, but few reported participating in prior treatment (Rainone et al., 1987; Roffman & Barnhart, 1987). We have argued that marijuana-specific treatments may be needed to attract individuals who are not abusing other drugs (see Stephens & Roffman, 1993). Others have promoted adaptations of 12-step approaches to the treatment of marijuana dependence (N. S. Miller, Gold, & Pottash, 1989; Zweben & O'Connell, 1988), but a learning- Robert S. Stephens, Department of Psychology, Virginia Polytechnic Institute and State University; Roger A. Roffman, School of Social Work, University of Washington; Edith E. Simpson, Department of Sociology, University of Washington. This research was supported by Grant 2 RO1 DA03586 from the National Institute on Drug Abuse. The opinions expressed are our own. Appreciation is expressed to the anonymous reviewers for their helpful comments and to Bonnie Cleaveland for assistance in conducting analyses and preparing this article. Correspondence concerning this article should be addressed to Robert S. Stephens, Department of Psychology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia Electronic mail may be sent to stephens@vtvm based conceptualization of excessive use and treatment may be more consistent with the personal and sociocultural beliefs of many marijuana users who began using in an era when the prevailing notion was that marijuana was not addictive (Stephens & Roffman, 1993). Marlatt and Gordon's (1980, 1985) relapse prevention (RP) treatment model promotes the beliefs that addiction or dependence is primarily a learned behavior and that relapse is a failure of behavioral and cognitive coping skills rather than a physiologically based loss of control over substance use. The assumptions of the RP model are consistent with findings of minimal levels of tolerance and with only minor withdrawal symptoms associated with repeated use of marijuana (e.g., Jones, Benowitz, & Herning, 1981), which suggests that physiological factors play a minimal role in the maintenance of marijuana use. There are few published tests of the RP model in its entirety, but preliminary research has demonstrated the effectiveness of some components of the RP model in reducing alcohol abuse (Chancy, O'Leary, & Marlatt, 1978), cigarette smoking (Hall, Rugg, Tunstall, & Jones, 1984; Stevens & Hollis, 1989), and weight problems (Perri, Shapiro, Ludwig, Twentyman, & Mc- Adoo, 1984). Other studies have failed to support the effectiveness of various RP techniques (e.g., Berg & Skuttle, 1986; Brown, Lichtenstein, Mclntyre, & Harrington-Kostur, 1984; Curry, Marlatt, Gordon, & Baer, 1988; Davis & Glares, 1986; Ito, Donovan, & Hall, 1988; Supnick & Colletti, 1984). Small sample sizes, inconsistent conceptualization of the RP intervention, and failure to establish treatment fidelity in some studies (see Moncher & Prinz, 1991) make it difficult to interpret the mixed findings. To evaluate the efficacy of an RP treatment for marijuanadependent adults, we operationalized most of the RP intervention techniques described by Marlatt and Gordon (1985) and compared them to a nonbehavioral, group discussion treatment. The RP treatment focused on identifying high-risk situations for relapse, acquiring behavioral and cognitive coping skills through skill-training and role-playing exercises, and attending to lifestyle balance. The comparison treatment was la-

2 TREATING ADULT MARIJUANA DEPENDENCE 93 beled social support (SSP) because of the recurring theme of using group members for support during the change process. The SSP treatment used a group process model of therapeutic change and was based on the content of local substance abuse programs. We hypothesized that subjects assigned to the RP treatment would achieve and maintain superior outcomes in comparison with subjects assigned to the SSP treatment in terms of decreased marijuana use and fewer related problems. Alcohol and other drug use was assessed to determine whether treatments or changes in marijuana use were associated with changes in other substance use. Subjects Method Subjects were 212 men (n = 161) and women (n = 51) recruited through media announcements that promoted a treatment and research program for adults who wanted help with quitting marijuana use. The subjects' mean age was years (range, years); 95% were White; 44% were married; 40% had completed some college; and 85% were employed. Of the 382 men (n = 290) and women (n = 92) who completed screening questionnaires, 73 (19%) were ineligible because they reported evidence of recent abuse or dependence on alcohol or other drugs. 1 Nine other subjects were excluded because they had used marijuana fewer than 50 times in the past 90 days; 2 were excluded because they were currently in other treatment, and 1 was excluded because psychotic thought processes were evident. Of the 297 eligible subjects, 85 failed to complete all pretreatment assessment and enrollment procedures; thus, they were not assigned to treatment. 2 Design Subjects were recruited and treated in two cohorts approximately 2 months apart. In each cohort, eligible subjects were blocked on sex and randomly assigned to either the RP (n = 106) or the SSP (n = 106) treatment condition. Two teams of cotherapists conducted the RP intervention and two different cotherapist teams conducted the SSP treatment, with each team conducting two groups in each cohort for a total of 16 groups. Therapists were unaware of the specific content of the alternative treatment and hypotheses of the study. Assessment of drug use and related psychosocial variables occurred before treatment, at the final treatment session, and at 1, 3,6, 9, and 12 months posttreatment. Procedures Pretreatment. Individuals who responded to media announcements in the greater Seattle, Washington, area were referred to group orientation sessions in university classrooms where we explained the study and they completed screening questionnaires. Subjects paid a $50 deposit, which we refunded in five $10 payments contingent on the subjects' completion of the 1-, 3-, 6-, 9-, and 12-month posttreatment assessments. Participants were required to identify a family member or friend to serve as a collateral verifier of posttreatment marijuana and other drug use. Measures of marijuana and other drug use and abuse, psychological distress, reasons for seeking treatment, and history of other addictive behavior patterns were then completed. Subjects took home questionnaires that measured socioeconomic status, social support, and weekly use of other drugs, and they returned the questionnaires when attending a second group assessment session 1-2 weeks later. During the second group assessment session, eligible subjects completed measures of self-efficacy and coping, attributional style, and personality. Treatment. All treatment groups met weekly for the first 8 weeks and then every other week for the next 4 weeks for a total of 10 2-hr sessions. Subjects in both conditions were expected to cease marijuana use by the fourth group session. Controlled or moderate marijuana use was not promoted as a viable goal in either treatment. Concurrent participation in self-help fellowships (e.g., Marijuana Anonymous) was discussed briefly with participants in both conditions as an option. A questionnaire assessing perceptions of treatment helpfulness and therapists' attributes was mailed to subjects after the fifth session. Treatment groups consisted of subjects and a male-female cotherapist team. Each team had 1 master's- or PhD-level therapist with group experience and a second therapist in training for the master's degree. Therapists with a background in cognitive-behavioral interventions were chosen for the RP interventions, whereas those with primarily group process orientations led SSP groups to maximize therapist competence and enthusiasm for the respective treatments. RP therapist training was conducted by Roger A. Roffman and consisted of studying a detailed therapist manual and rehearsing specific activities in four 2- hr training sessions. SSP therapists reviewed a similarly constructed therapist manual and were trained by a local drug-abuse treatment consultant who was not familiar with the RP approach. After treatment groups started, therapist teams met in weekly 2-hr sessions with the respective supervisors to debrief the previous sessions, plan and rehearse the subsequent sessions, and maintain adherence to the treatment protocols. All treatment sessions were audiotaped. The RP intervention was adapted from a therapist manual for a cigarette smoking-cessation program using the relapse prevention approach (Gordon & Curry, 1984) and closely followed the sequence of interventions described by Marlatt and Gordon (1985). Therapists adopted an active problem-focused, psychoeducational style. Initial sessions generated motivation and commitment to the change process by eliciting reasons for quitting, providing information on marijuana effects, reviewing autobiographical histories of marijuana use, and discussing self-monitored marijuana use and high-risk situations for relapse. Quit ceremonies and contracts formalized commitment in the fourth session. Thereafter, therapists debriefed encounters with high-risk situations during the previous week and modeled coping skills in role-plays specific to the reported high-risk situation. Planned exercises (e.g., relaxation and assertion training) and handouts further exposed subjects to possible coping strategies. Homework assignments focused on anticipating highrisk situations, practicing coping skills, and enlisting the support of others in the social environment. "Lifestyle balance" was introduced through self-monitoring and rating of daily activities in terms of "shoulds" and "wants." Homework assignments encouraged inclusion of daily self-rewards. In later sessions, subjects created "relapse roadmaps" to identify how they might set themselves up for a lapse and practiced self-statements to reframe the cognitive and affective reactions to a lapse. The central theme of the SSP condition was the usefulness of group support during the drug cessation process. In each session therapists initially presented information or hypothetical case studies to stimulate discussion of topics related to the use and cessation of marijuana. Topics included getting and giving support, dealing with mood swings, faltering in motivation, identifying and dealing with denial, and relating to peers who continue to use. Although some topics overlapped content in the RP condition (e.g., dealing with negative affect and social pressure to use), SSP therapists did not give advice or train subjects in behavioral 1 Subjects were excluded if they self-reported dependence on alcohol or another drug or reported adverse consequences and pathological symptoms of use (e.g., inability to stop using, withdrawal symptoms, seeking treatment). See Stephens, Roffman, and Simpson (1993) for a description of the full sample screened for participation. 2 Eligible subjects who did not complete pretreatment assessment did not differ from subjects who were randomized to treatment on sociodemographic or marijuana use variables.

3 94 R. STEPHENS, R. ROFFMAN, AND E. SIMPSON or cognitive coping techniques. SSP therapists facilitated discussion by directing questions to other members of the group and avoided direct input of any kind. Posttreatment. Booster treatment sessions were conducted for all treatment groups 3 and 6 months after the final session. No new treatment techniques were introduced at these sessions and therapists used the same intervention styles that they had used during earlier sessions. Questionnaires assessing marijuana use, other drug use, and related psychosocial variables were completed in group assessment sessions immediately following the final treatment session as well as after the 3- and 6-month booster sessions. Questionnaires were mailed to subjects who did not attend the group assessment sessions, and we mailed questionnaires to all subjects at the 1-, 9-, and 12-month posttreatment points. We independently mailed questionnaires to all collateral verifiers that assessed subjects' use of marijuana and other drugs at each posttreatment assessment. In some cases only essential marijuana use data were obtained from subjects in brief phone interviews because questionnaires were not returned. Urine samples were collected at the 3- and 6-month posttreatment assessments, and subjects were screened with an enzyme multiplied immunoassay technique analysis to verify the presence or absence of cannabinoid and other drug metabolites, excluding alcohol. Positive findings were confirmed by gas chromatography-mass spectrometry. Measures Marijuana use. Age of first use, age of first daily or near daily use, total years of use, and the number of previous attempts to quit were assessed to describe the chronicity of marijuana use. The number of times marijuana was used on a typical day of use in the past 90 days was reported on a 4-point scale that included once (1), 2-3 times (2), 4-5 limes (3), and 6 or more times (4) per day. The number of days on which marijuana was used served as the primary dependent measure. At each assessment point, subjects reported the number of days of use in the past 90 days (the past 30 and 60 days at the 1-month and 3-month posttreatment assessments, respectively). The number of days of use was divided by the number of months in the time frame to yield comparable indices of monthly frequency of use across assessments. Alcohol and other drug use. At all assessment points, subjects were prompted to refer to a calendar prior to recording the number of times they used alcohol and other drugs during each week of the recall period (past 3 months or since the previous follow-up). Drug use each week was averaged across the weeks in the reporting period to yield indices of alcohol, heroin, methadone, other opiate, cocaine, barbiturate (other sedative), tranquilizer, amphetamine, and hallucinogen use at each follow-up. The average weekly uses of the drugs other than alcohol were averaged to create a single index of other drug use. Drug-related problems. To characterize pretreatment severity of marijuana abuse, subjects completed a modified version of the 20-item Drug Abuse Screening Test (DAST; Skinner, 1982). The DAST has good internal consistency and measures severity of drug abuse unidimensionally with a total score created by summing unweighted affirmative responses (Skinner, 1982). Subjects completed the DAST only in reference to their use of marijuana (2 items specifically targeting other drug use were deleted, which resulted in a possible range of 0-18). Subjects reported problems related to the use of marijuana, alcohol, and other drugs in the past 90 days by using lists of negative social, occupational, and legal consequences at the pretreatment assessment and at 3, 6 and 12 months posttreatment. Responses were summed to create indices of the number of problems associated with marijuana (range, 0-24), alcohol (range, 0-20), and other drug use (range, 0-24). Collateral verification. Collateral verifiers estimated the number of days on which the subjects used marijuana in the past 90 days (30 and 60 days at the 1 - and 3-month follow-ups, respectively) and indicated whether the subjects "experienced problems in personal, social, occupational, or physical functioning" that were due to the use of marijuana, alcohol, or other drugs. Collateral verifiers also provided estimates of the number of times since the previous follow-up that the subjects used alcohol and each of the other drugs. Pretreatment Marijuana Use Results Table 1 shows pretreatment and historical use of marijuana. The typical subject was a daily or near daily marijuana user by age 20 years and had used for 15 years. In the past 90 days, the mean number of days of use was 81, and more than one half of the sample used marijuana four or more times on a typical day of use. The DAST score exceeded the diagnostic cutpoint of 5 (Gavin, Ross, & Skinner, 1989) for 89% of the sample. Subjects in the two cohorts were compared with multivariate analyses of variance (MANOVAs) that were performed on groups of related pretreatment variables, and chi-square analyses that were performed on categorical variables. There were no significant differences, and data were collapsed across cohorts. Treatment Participation and Fidelity The mean number of treatment sessions attended was 7.6 (SD = 2.52), excluding booster sessions. 3 When treatment completion was denned as attending 7 or more of the 10 sessions, including either Session 9 or 10, 146 (69%) subjects met the criterion. There were no significant differences in attendance or completion rates between the RP and SSP conditions. Subject participation in other drug use treatments (M = 3%; range, 2%- 4%) or self-help groups (M = 9%; range, 8%-12%) at each follow-up was minimal. Mean ratings of therapist teams on bipolar adjective scales after the fifth session showed that therapists were perceived positively. A MANOVA comparing RP and SSP therapists on these rating scales resulted in a significant multivariate effect, F(\2, 168) = 1.87, p <.05. The cold-warm and unsociable-sociable scales showed significant univariate effects with RP therapist teams rated as relatively warmer and more sociable than SSP therapist teams. The differences in warmth and sociability ratings may relate to SSP therapists avoiding direct input and referring questions to other group members. RP and SSP therapists did not differ on scales assessing caring, optimism, competence, helpfulness, sensitivity, activity, enthusiasm, friendliness, interest, and nurturance. After the 10th treatment session, subjects completed three scales assessing (a) perceptions of the treatments' helpfulness in "stopping" and "staying off marijuana" and (b) the likelihood of the subjects' "recommending the program" to someone else. Means on 7-point scales ranging from not at all helpful (I) to 3 Booster sessions were attended by fewer than 50% of the sample, and there was no difference across treatment conditions. Analyses indicated that subjects who attended booster sessions were using marijuana less often in the months preceding the sessions than were subjects who did not attend. There was no indication that attendance at booster sessions enhanced outcomes at future follow-ups beyond these preexisting differences.

4 Table 1 Pretreatment Marijuana Use TREATING ADULT MARIJUANA DEPENDENCE 95 Randomized sample (H = 212) Follow-up sample («= 167) Variable M SD M SD Age of first use Age of daily use Years of use" No. previous attempts to quit Days of use, past 90 days Times used per day, past 90 days b DAST" Note. DAST = Drug Abuse Screening Test (Skinner, 1982). " Subjects who did not complete all follow-ups (n = 45) differed from those who did (n = 167), p <.05, on these variables. b 1 = once, 2 = 2-3 times, 3 = 4-5 times, 4 = 6 or more times. extremely helpful (7) and from not at all likely (1) to extremely likely (7) were all above 5, which indicated generally high perceptions of treatment efficacy and did not differ significantly between treatment conditions. A M ANOVA performed on subjects' posttreatment ratings of the frequency of 19 treatment experiences revealed a significant multivariate effect of treatment condition, F([9, 168) = 51.95, p <.0001; there were significant univariate effects on 12 of the 19 scales. Results supported treatment fidelity in that RP subjects reported a greater focus on the acquisition of coping skills, homework assignments, relaxation training, high-risk situations, coping with urges to use and with friends who use marijuana, modeling of coping skills by therapists, role-playing of coping techniques by group members, and planning for future tempting situations. Conversely, SSP subjects were more likely to report group discussions focused on the denial of marijuanarelated problems, improving relationships damaged by marijuana use, and giving support to others who were trying to stop marijuana use. Two raters who were unaware of the treatment condition rated 32 audiotapes of therapy sessions (RP = 16; SSP = 16) for the frequency of 27 treatment-specific and treatment-nonspecific therapy experiences. Two sessions from each of the 16 therapy groups were randomly selected for rating under the constraint that all stages of the treatment process were represented approximately equally. Ratings were averaged across raters. Interrater reliabilities (alpha) ranged from.58 to.96 (M =.81) across the 27 treatment experiences and were above.70 on all but five items. The analyses of variance that we performed on these independent ratings resulted in significant treatment differences (ps <.05) for 16 of the 27 treatment experiences. Results confirmed the differences identified by subjects' ratings and indicated additional differences in treatment processes that were not rated by the subjects. SSP therapists were rated as being more likely to encourage the discussion of issues with other group members, to promote discussion using case examples or issues related to drug cessation, and to encourage discussion of how denial of marijuana problems by family members contributed to the problem. RP therapists were observed to focus more on how to deal with a slip into marijuana use so as to avoid relapse and on how to encourage self-talk as a technique for coping with faltering motivation. Marijuana, Alcohol, and Other Drug Outcomes Validity of self-reports. Self-reports of posttreatment marijuana and other drug use were obtained from 193 (91%), 177 (83%), 185 (87%), 187 (88%), and 194 (92%) subjects at the 1-, 3-, 6-, 9-, and 12-month follow-ups, respectively. Collateral verifiers' reports of subjects' posttreatment drug use were obtained for 96% of these subjects. Self-reported and collateral- verifierreported abstinence from marijuana for the period since the previous follow-up showed uniformly high agreement across follow-ups (M = 91 %). The average correlation between the subjects' and the collateral verifiers' reports of days of marijuana use was.82. Subjects and collateral verifiers agreed on the existence of problems related to marijuana use 63% of the time. Only 12% of the disagreements regarding abstinence and 7% of the discrepancies regarding problems were related to underreports of use or problems by subjects in relation to collateral verifiers. The correlations between subject and collateral verifier reports of the number of times alcohol was used were somewhat lower (mean r =.50), but there was no tendency for collateral verifiers to systematically overreport alcohol use in relation to subjects. The correlation between subject and collateral verifier reports of other drug use was even lower (mean r =.29), which may have been due to the restricted range of use. However, in only 6% of all comparisons did collateral verifiers report more use of other drugs than did subjects. Agreement on the existence of problems related to alcohol and other drug use was 76.3% and 91.5%, respectively, with only a small proportion of the disagreements being related to subjects' underreporting problems in relation to collateral verifiers. Urine samples from 106 subjects at the 3-month follow-up and from 85 subjects at the 6-month follow-up agreed with subjects' reports of marijuana and other drug use 91% and 80% of the time, respectively. All disagreements resulted from subjects reporting use when test results were negative. Taken together, the data provide strong support for the validity of subjects' self-reported marijuana use and for problems related to mari-

5 96 R. STEPHENS, R. ROFFMAN, AND E. SIMPSON Table 2 Days of Marijuana Use per Month and Number of Related Problems Days of use Number of problems RP (n = 80) SSP(n = 87) SSP (n = 77) Assessment M SD M SD M SD M SD Pretreatment Posttreatment 1 month 3 month 6 month 9 month 12 month Note. RP = relapse prevention. SSP = social support. Dashes indicate data not available. juana, alcohol, and other drug use. The validity data for alcohol and other drug use were less strong but did not show systematic biases. Marijuana use and problems. In the remainder of this article, outcome analyses are presented for a subsample of 167 subjects (79% of the original sample) who completed all of the posttreatment assessments. 4 Subjects who completed all follow-ups (n = 167) were compared with subjects who did not (n = 45) using 2 (follow-up completion) X 2 (treatment condition) MA- NOVAs on groups of related pretreatment variables and chisquare analyses on categorical variables. Subjects included in the outcome analyses were significantly more likely to be female (27%) and married (48%) and to have completed a college degree (43%). They also reported fewer years of marijuana use and a lower DAST score (see first and third columns, Table 1). A significant interaction of follow-up completion and treatment condition indicated that RP subjects who completed all followups used marijuana fewer times per day than did SSP subjects who completed all follow-ups. This pattern was reversed for subjects who did not complete all follow-ups and suggested differential attrition from the follow-up sample as a function of treatment condition. Therefore, differential effects of treatment were tested using multivariate analyses of covariance (MAN- COVAs) with pretreatment level of typical daily use as the covariate. Sex of subject was included as a between-subjects variable to test for differential response to treatments. Table 2 shows the mean days of marijuana use at each assessment. The 2 (treatment) X 2 (sex) MANCOVA performed on monthly frequency of use at the 1-, 3-, 6-, 9-, and 12-month follow-ups did not reveal significant multivariate effects of the covariate, treatment, sex, or the interaction of treatment and sex (ps >. 19). The number of days of marijuana use per month at each assessment was also analyzed in a 2 (sex) X 6 (time) M ANOVA where time was a within-subjects variable representing the repeated pretreatment and posttreatment assessments. Multivariate results based on Pillai's statistic converted to an approximate.f statistic showed only a significant effect of time, F(5, 161) = 82.47, p <.001. Comparisons of pretreatment frequency of use with each follow-up indicated that subjects reported fewer days of marijuana use at every posttreatment assessment (all ps <.001). The 2 (treatment) X 2 (sex) MANCOVA performed on marijuana problems at the posttreatment assessments with pretreatment typical daily marijuana use as the covariate did not reveal any significant effects (ps >.11). The 2 (sex) X 4 (time) MA- NOVA performed on the number of problems related to marijuana use pretreatment and 3, 6, and 12 months posttreatment resulted only in a significant effect of time, F(3, 148) = 57.44, p < The mean number of problems reported at each posttreatment assessment was significantly reduced in comparison with pretreatment levels (all ps <.001, see Table 2). Abstinence and improved outcomes. Approximately 65% of the subjects were abstinent for at least the first 2 weeks following the quit date (Session 4), and 63% of subjects reported abstinence during the last 2 weeks of the treatment period. Chisquare analyses revealed no significant differences between treatment conditions (ps >.70) or gender (ps >.22) in the rates of quitting or end of treatment abstinence. There were no significant effects of treatment condition (ps >.30) or sex (ps >.09) at any follow-up on the rates of continuous posttreatment abstinence shown in Figure 1. Point abstinence rates (i.e., abstinence for the period since the previous follow-up) also did not show effects of treatment (all ps >.50), with 49%, 39%, 24%, 22%, and 20% of the subjects reporting abstinence at the 1-, 3_ ) 6-, 9-, and 12-month follow-ups, respectively. A significant difference in point abstinence rates between men and women found at the 3-month follow-up, x 2 0, N = 167) = 3.89, p <.05, remained marginally significant at the 6-, 9-, and 12-month follow-ups (ps <.13,.10, and.08, respectively). Men reported higher rates of abstinence (43%, 27%, 25%, and 24%) than did women (27%, 16%, 13%, and 11%) at each point. Men and women did not differ on point abstinence rates at the 1-month follow-up. Improved, moderate use outcomes were coded for nonabstinent subjects at the 3-, 6-, and 12-month follow-ups if their fre- 4 Results do not change when all subjects who completed a given follow-up are included and pretreatment marijuana use is used as a covariate or when analyses were repeated using log (x + 1) transformations on drug use and problem indices to reduce skew. 5 The sample size is reduced in analyses of marijuana-, alcohol-, and drug-related problems and of alcohol and other drug use because these data were not available for subjects reporting marijuana use by means of phone interviews at one or more follow-ups.

6 TREATING ADULT MARIJUANA DEPENDENCE 97 quency of marijuana use during the preceding 90 days was 50% or less of their pretreatment levels and if they reported no problems related to marijuana use in the same time period. Improvement throughout the 12-month follow-up was coded for subjects who were either abstinent or improved at each followup. Overall, 36% of the sample was abstinent or improved 12 months after treatment, and 31 % were abstinent or improved for the entire 12 months (see Table 3). Chi-square tests of differential effects of treatment and sex using the tripartite categorization (abstinent, improved, or not improved) revealed a marginally significant effect of treatment only at the 3-month follow-up, x 2 (2, N ~ 167) = 5.64, p <.06. RP subjects were more likely to report the nonproblematic, reduced-use pattern (Table 3). However, subsequent analyses indicated that differential rates of improvement were significant for men (RP = 29%; SSP = 8%), x 2 (2, N = 122) = 9.65, p <.01, but not for women (RP = 27%; SSP = 30%), X 2 (2, N = 45) = 0.59, p >.74. This Treatment X Sex interaction was not found at the 6- and 12-month follow-ups or for improvement across the entire follow-up period (ps >.76). Women (33%) were more likely to be classified as improved than men (17%) at the 6-month follow-up regardless of treatment condition, whereas men (28%) were more likely to be abstinent than women (16%), x 2 (2,N= 165) = 6.35,p<.05. Alcohol and other drug outcomes. Sex X Time MANOVAs revealed a marginally significant effect of time on the average weekly frequency of alcohol use, F(5, 146) = 2.11, p <.07, and Months Posttreatment 12 Figure I, Continuous abstinence rates by treatment conditions. RP = relapse prevention; SSP = social support. Table 3 Percentage Abstinent, Improved, and Not Improved Follow-up 3 month" Abstinent Improved Not improved 6 month Abstinent Improved Not improved 12 month Abstinent Improved Not improved Cumulative Abstinent Improved Not improved RP (n = 80) Total Note. RP = relapse prevention. SSP = social support. " There were significant differences between RP and SSP conditions (p <.1). SSP (n = 87) a significant effect of time on alcohol-related problems, F(3, 156) = 4.18, p <.01, but no main or interaction effects of sex. Frequency of alcohol use increased from 2.33 times per week (SD = 3.27) pretreatment to an average of 2.82 times per week (SD = 3.39) across the posttreatment assessments. Alcohol-related problems showed an increase from a mean of 0.26 (SD = 0.74) pretreatment to 0.55 (SD = 0.94) across the follow-ups. Treatment X Sex MANCOVAs controlling for pretreatment differences in typical daily marijuana use performed on the weekly alcohol use and problem indices did not reveal significant effects of treatment or sex. Pretreatment weekly use of other drugs was 0.33 (SD = 1.39), and problems related to other drugs was 0.16 (SD = 0.54). There were no significant effects of time, treatment condition, or sex on other drug use and related problems. The number of pretreatment alcohol problems was subtracted from the number reported at the 3-, 6-, and 12-month follow-ups to create indices of increased alcohol problems. Posttreatment marijuana use, expressed as a percentage of pretreatment marijuana use, was minimally correlated with increased alcohol problems at the 3-month follow-up (.06; p >.22), at the 6-month follow-up (.16; p <.02), and at the 12- month follow-up (.18; p <.02). Increased alcohol problems tended to be related to less reduction in the use of marijuana. Discussion This appears to be the first controlled treatment-outcome study focused specifically on adult marijuana use. Substantial reductions in the amount of marijuana use and related problems were found in both treatment conditions throughout the 12-month posttreatment follow-up. Careful attention to the operationalization and validation of the RP intervention, a rela-

7 98 R. STEPHENS, R. ROFFMAN, AND E. SIMPSON lively large sample, and a group discussion comparison condition provided a strong test of the RP model (Marlatt & Gordon, 1985) with adult marijuana users. However, there were few significant differences in outcomes between the two treatment conditions. Significant reductions in marijuana use and related problems were evident. Nearly two thirds of the subjects initially achieved abstinence, and one third showed signs of improvement throughout the 12 months of follow-up. Collateral verification of reductions in days of use and problems confirmed the selfreported findings. However, sustained abstinence was the exception, with only 14% of subjects reporting no marijuana use throughout the follow-up period. The relapse curve was steep in the first several months posttreatment and similar to those found in the treatment of other addictive behaviors (Hunt, Barnett, & Branch, 1971). Outcomes were in the range obtained in alcohol and cigarette treatment studies. In general, the results failed to support our hypothesis that the RP intervention would produce superior reductions in marijuana use and associated problems. RP and SSP subjects did not differ in posttreatment days of marijuana use, abstinence rates, or numbers of reported problems. Men in the RP condition were more likely to be classified as improved at the 3-month follow-up and were apparently able to forestall a return to higher levels of use with associated problems. Although this finding is consistent with the RP focus on avoiding full-blown relapse following an initial lapse, treatment differences were not present at subsequent follow-ups. It is also unclear why women did not display the same effect, and replication of this finding is needed. The lack of differential treatment effects for the RP model is consistent with other recent findings in the areas of alcohol (Berg & Skuttle, 1986; Ito et al., 1988) and cigarette cessation (Brown et al., 1984; Curry et al., 1988; Supnick & Colletti, 1984). In the present study, the significance of the failure to find a differential effect of RP is increased by the relatively large sample and attention to treatment fidelity. Subject and independent observer ratings corroborated the fidelity of an RP treatment that was based closely on the writing of Marlatt and Gordon (1985). The RP approach did not appear to provide an advantage relative to a credible comparison group treatment that focused discussion on topics typically related to drug cessation. Nonspecific factors associated with group support and a general readiness for change in this self-selected sample may account for the similar results. However, we did not directly assess the acquisition of new skills or compliance with homework assignments. It remains possible that RP subjects did not acquire the coping skills hypothesized to moderate outcomes despite the therapy activities designed to promote them. There was evidence of differential outcomes as a function of sex. Women appeared less likely than men to maintain abstinence outcomes and were somewhat more likely to report nonproblematic use of marijuana. The data suggest that women were more likely to forego abstinence and yet avoid complete relapse. However, the difference in moderate, nonproblematic use was no longer evident at the 12-month follow-up. At least one other study (W. R. Miller & Joyce, 1979) found more controlled drinking outcomes among women following alcohol treatment. Replication and explication of this gender effect is needed. A significant increase in the posttreatment frequency of alcohol use and related problems occurred but was not clearly related to cessation of marijuana use. The increase in the number of alcohol problems was small and tended to be correlated with less reduction in marijuana use. The same factors that interfered with reduced marijuana use in some individuals may have contributed to the increase in alcohol use and related problems. It is also possible that the increase over time simply reflected regression toward the mean in a sample screened to be without problems. Future studies using a finer grained assessment of alcohol use in samples with greater variability in alcohol problems may help clarify these findings. Problems related to the use of drugs other than marijuana or alcohol remained minimal throughout the follow-up period with no evidence of a significant increase posttreatment. In general, the data did not indicate that focusing exclusively on cessation of marijuana use promoted an increase in other substance use. In the absence of clear treatment differences and a no-treatment control group, it is not possible to attribute outcomes to the treatments with certainty. However, the pretreatment chronicity and intensity of marijuana use, the number of problems associated with use, and the report of multiple prior attempts to quit suggest that the substantial reductions in posttreatment use were at least partially a product of the interventions. Attrition during the follow-up period suggests that the results are more representative for a subsample that includes more women and those who are married, better educated, and reporting fewer problems related to marijuana. These data establish the appeal and efficacy of group counseling approaches to the treatment of adult marijuana use and at the same time indicate the resistance of the behavior to change. Generalization of results presented here is limited by the selfselected nature of the sample, the university research setting, and the failure to attract non-white racial groups. We have argued that the pretreatment symptom constellation is consistent with the dependence syndrome concept (Stephens & Roffman, 1993), although diagnostic interviews were not used in the present study and are needed to confirm diagnosable disorder. Similar studies in existing drug treatment agencies would help to assess the generalizability of the findings. Nevertheless, these data indicate that some adult marijuana users are interested in treatment and can be effectively helped to reduce their use. Future studies using no-treatment control groups are needed to establish rates of unassisted quitting. Comparisons of treatments that vary in format and content are needed to replicate and extend findings regarding the efficacy of intervening with this population. References Berg, G., & Skuttle, A. (1986). Early interventions with problem drinkers. In W. R. Miller & N. Heather (Eds.), Treating addictive behaviors: Processes of change (pp ). New York: Plenum Press. Brown, R. A., Lichtenstein, E., Mclntyre, K. Q, & Harrington-Kostur, J. (1984). Effects of nicotine fading and relapse prevention on smoking cessation. Journal of Consulting and Clinical Psychology, 52, Chancy, E. E, O'Leary, M. R., & Marlatt, G. A. (1978). Skill training

8 TREATING ADULT MARIJUANA DEPENDENCE 99 with alcoholics. Journal of Consulting and Clinical Psychology, 46, Curry, S. J., Marlatt, G. A., Gordon, J., & Baer, J. S. (1988). A comparison of alternative theoretical approaches to smoking cessation and relapse. Health Psychology, 7, Davis, J. R., & Glaros, A. G. (1986). Relapse prevention and smoking cessation. Addictive Behaviors, 11, Gavin, D. R., Ross, H. E., & Skinner, H. A. (1989). Diagnostic validity of the Drug Abuse Screening Test in the assessment of DSM-III drug disorders. British Journal of Addiction, 84, Gordon, J. R., & Curry, S. G. (1984). Quitting smoking: A manual for group facilitators. Unpublished manuscript, University of Washington, Seattle. Haas, A. P., & Hendin, H. (1987). The meaning of chronic marijuana use among adults: A psychosocial perspective. Journal of Drug Issues, 77, Hall, S. M., Rugg, D., Tunstall, C, & Jones, R. T. (1984). Preventing relapse to cigarette smoking by behavioral skills training. Journal of Consulting and Clinical Psychology, 52, Hunt, W. A., Barnett, L. W., & Branch, L. G. (1971). Relapse rates in addiction programs. Journal of Clinical Psychology, 27, Ito, R. J., Donovan, D. M., & Hall, J. J. (1988). Relapse prevention in alcohol aftercare: Effects on drinking outcome, change process, and aftercare attendance. British Journal of Addiction, 83, Jones, R. T, Benowitz, N. L., & Herning, R. I. (1981). Clinical relevance of cannabis tolerance and dependence. Journal of Clinical Pharmacology, 21, 143S-152S. Marlatt, G. A., & Gordon, J. R. (1980). Determinants of relapse: Implications for the maintenance of behavior change. In P. O. Davidson & S. M. Davidson (Eds.), Behavioral medicine: Changing health lifestyles (pp ). New York: Brunner/Mazel. Marlatt, G. A., & Gordon, J. R. (1985). Relapse prevention: Maintenance strategies in the treatment of addictive behaviors. New York: Guilford Press. Miller, N. S., Gold, M. S., & Pottash, A. C. (1989). A 12-step treatment approach for marijuana (cannabis) dependence. Journal of Substance Abuse Treatment, 6, Miller, W. R., & Joyce, M. A. (1979). Prediction of abstinence, controlled drinking, and heavy drinking outcomes following behavioral self-control training. Journal of Consulting and Clinical Psychology, 47, Moncher, F. J., & Prinz, R. J. (1991). Treatment fidelity in outcome studies. Clinical Psychology Review, 11, National Institute on Drug Abuse. (1991). National household survey on drug abuse 1990 population estimates. Washington, DC: U.S. Government Printing Office. Negrete, J. C. (1988). What's happened to the cannabis debate? British Journal of Addiction, 83, Perri, M. G., Shapiro, R. M., Ludwig, W. W., Twentyman, C. T., & McAdoo, W. G. (1984). Maintenance strategies for the treatment of obesity: An evaluation of relapse prevention training and posttreatment contact by mail and telephone. Journal of Consulting and Clinical Psychology, 52, Rainone, G. A., Deren, S., Kleinman, P. H., & Wish, E. D. (1987). Heavy marijuana users not in treatment: The continuing search for the "pure" marijuana user. Journal of Psychoactive Drugs, 19, Roffman, R. A., & Barnhart, R. (1987). Assessing need for marijuana dependence treatment through an anonymous telephone interview. International Journal of the Addictions, 22, Skinner, H. A. (1982). The Drug Abuse Screening Test. Addictive Behaviors, 7, Stephens, R. S., & Roffman, R. A. (1993). Adult marijuana dependence. In J. S. Baer, G. A. Marlatt, & R. J. McMahon (Eds.), Addictive behaviors across the lifespan: Prevention, treatment, and policy issues (pp ). Newbury Park, CA: Sage. Stephens, R. S., Roffman, R. A., & Simpson, E. E. (1993). Adult marijuana users seeking treatment. Journal of Consulting and Clinical Psychology, 61, Stevens, V. J., & Hollis, J. F. (1989). Preventing smoking relapse, using an individually tailored skills-training technique. Journal of Consulting and Clinical Psychology, 57, Supnick, J. A., & Colletti, G. (1984). Relapse coping and problem solving training following treatment for smoking. Addictive Behaviors, 9, Zweben, J. C., & O'Connell, K. (1988). Strategies for breaking marijuana dependence. Journal of Psychoactive Drugs, 20, Received October 9,1992 Revision received March 9, 1993 Accepted March 15, 1993