CSAT funded MTP to design and conduct a study of the efficacy of treatments for marijuana dependence, to extend this line of research, and to broaden the applicability of the approach to a more diverse group than that used in earlier trials (Stephens et al. 1994b, 2000). The treatment sites were the University of Connecticut School of Medicine, Department of Psychiatry, Farmington, Connecticut; The Village South, Miami, Florida; and the University of Washington, School of Social Work, Seattle, Washington. The CC was at the University of Connecticut, Department of Psychiatry.
The study examined the efficacy of treatments of different durations for a diverse group of adults who were marijuana dependent. Two treatments—one lasting two sessions, the other nine sessions— were compared with a delayed treatment control (DTC) condition, in which subjects were offered treatment 4 months after their baseline assessment. The same counselors delivered treatments of both durations to avoid confounding the mode of treatment, length of treatment, and counselor experience. A case management component was incorporated in the longer treatment to help clients identify and overcome barriers to successful behavior change in their everyday environments. The hypothesis was the nine-session and two-session interventions would produce outcomes superior to the DTC in terms of higher abstinence rates and associated negative consequences. Although the
^The following section is adapted from MTP Research Group (in press).
limited prior research suggested no differences between brief and extended treatments, it also was hypothesized that the nine-session intervention would yield outcomes superior to the two-session intervention when delivered by counselors with the same level of expertise.
The study improved on the methodology of the previous treatment studies in several other ways. Structured diagnostic interviews were used to arrive at formal diagnoses of marijuana dependence, and the Addiction Severity Index, a widely used measure of problem severity, was included to compare the findings of this study with those of other studies of drug abuse. Supplemental reading B in section VII provides a detailed discussion of study methodology.
As the first well-controlled multisite trial of manual-guided treatments for marijuana dependence, this study produced several noteworthy findings:
• The results of the randomized trial suggest that both a two-session motivational enhancement therapy (MET) treatment and a nine-session treatment incorporating MET, coping skills training, and case management were significantly more effective in reducing marijuana use than a DTC condition.
• The more intensive the treatment, the better the outcomes.
• Outcomes of these brief treatments were durable; data from a 1-year followup of the treated groups demonstrated treatment's sustained effect even after treatment termination.
• Reductions in drug use were linked to other positive outcomes (e.g., sustained reductions in marijuana-related problems).
• Treatment effects were robust across a number of participant characteristics, including gender and ethnicity.
Taken together, these findings suggested that treatment for marijuana dependence was effective.
Few studies have evaluated active treatments with respect to a DTC condition. The findings from the DTC group are not consistent with the view that marijuana dependence is benign and that individuals improve without treatment. Instead, these findings suggest that well-structured treatments may be necessary to increase abstinence rates among the chronic marijuana-using population. Many subjects reported difficulties finding help for their marijuana-related problems through the current substance abuse treatment system.
The findings are also generally consistent with the results of prior studies of behavioral treatments for cannabis-related disorders (Budney et al. 1998; Stephens et al. 1994b, 2000) in suggesting that well-defined behavioral treatments for marijuana dependence produce encouraging improvement and that treatment is associated with meaningful benefits. These findings support other results in the literature pointing to the efficacy of behavioral treatments in producing significant and durable improvement for a range of substance-related disorders, particularly alcohol and cocaine dependence.
Findings indicate a robust dose-effect relationship for this study's treatments and contrast with earlier studies of cannabis treatment that have not demonstrated differences in outcome related to intensity. The MTP study, one of only a few studies that have focused on treatment intensity, contrasted the brief two-session treatment with the more intensive nine-session treatment; treatment participation was high in both conditions. However, further research is needed to determine whether treatment outcomes might be improved with more treatment or whether different distributions of treatment sessions might help people who use marijuana sustain the positive treatment outcomes.
In addition to the overall reductions observed in the frequency of marijuana smoking, reductions also were evident in marijuana dependence symptoms, marijuana-related problems, and anxiety symptoms. In each measure, the nine-session treatment group showed the greatest improvements, the two-session group showed intermediate reductions, and the DTC group showed little change.
Finally, countering the historical portrayal of marijuana as a benign drug, the MTP study and previous research (Stephens et al. 1993a, 1994b, 2000) suggest that individuals can develop recurrent psychological, social, and medical problems with chronic marijuana use. Individuals who use marijuana as their primary drug tend not to seek treatment in traditional drug treatment settings. Clients in real-life treatment settings, as compared with volunteers in randomized clinical trials, tend to present with complex difficulties in addition to substance use disorders. When people present for marijuana treatment, they may want and need help with family and other relationships, regulating their emotions, employment and financial problems, or addressing health worries. These problems may have preceded, resulted from, or co-occurred with the substance use difficulties. Increasing evidence suggests that counseling for marijuana dependence is effective and accompanied by other positive changes in clients' lives (Steinberg et al. 2002).
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