Practice Profile: Psychosocial Interventions for Cannabis Use Disorder

Using meta-analytic techniques, Dutra and colleagues (2008) analyzed the effect of psychosocial interventions on illicit substance use disorders, including use of cocaine, opiates, and cannabis; and on polysubstance abuse and dependence (the CrimeSolutions review of this meta-analysis focused on the effects of psychosocial interventions on cannabis use disorder). To identify studies, PsycINFO was used to find articles published up to March 2005, using a variety of key search terms, including but not limited to cocaine, substance use, substance abuse, treatment outcome, contingency, and voucher. Additionally, MEDLINE was used to identify articles available between 1966 and March 2005, and the Cochrane Central Register of Controlled Trials was used to identify studies for the first quarter of 2005. Both PsychINFO and MEDLINE searches were limited to those published in English.

To be eligible for inclusion in the meta-analysis, studies had to be investigations of the efficacy of individual psychosocial treatments for substance abuse/dependence (not including alcohol or nicotine abuse/dependence) and have used randomized controlled trials (RCTs), including a comparison group. Moreover, studies were limited to adult participants and to investigations on the efficacy of nonintensive outpatient treatments. Nonintensive outpatient treatment was defined as a maximum of three, 2-hour per week treatment sessions. Finally, studies had to include self-report outcomes of interest or toxicology screening outcomes of interest. Self-report outcomes of interest included 1) mean maximum number of days or weeks abstinent throughout treatment, 2) mean percent of days abstinent throughout treatment, 3) percent of sample that demonstrated abstinence for 3 or more weeks throughout treatment, 4) percent of sample that demonstrated posttreatment/clinically significant abstinence, and 5) posttreatment scores on the Addiction Severity Index. Toxicology outcomes of interest included 1) mean number of negative drug screens throughout treatment, 2) mean percent of negative drug screens throughout treatment, and 3) percent of sample that demonstrated clinically significant abstinence.

A total of 34 RCTs were included in the review, which involved 2,340 total participants. The majority of participants across all studies were male (62.2 percent) and white (61.0 percent). The average age of the participants was 34.9 years and self-reported an average of 10.1 years of substance use. Of the 34 total studies, five specifically examined the effects of psychosocial interventions for cannabis use disorder. Across the five studies, the intent-to-treat sample (i.e., the sample size of the treatment condition) included 470 participants (this did not include the sample size of participants in the control condition, which was not provided). For treatment type, one study looked at contingency management, two studies looked at cognitive–behavioral therapy (CBT) interventions, and two studies looked at relapse prevention. In two studies, the control condition received motivational enhancement interviewing, two studies included wait-list control conditions, and one study included a treatment-as-usual control condition. The weeks of treatment ranged from 4 to 18, with one session per week.

The effect sizes for the outcome variable (cannabis use) were calculated using Cohen’s d. Aggregated mean effect sizes were determined when studies presented data on two or more of the chosen outcome variables.

Gates and colleagues (2016) conducted a meta-analysis to determine the effectiveness of psychosocial interventions for cannabis use disorder. Studies were obtained through the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, PsycINFO, the Cumulative Index to Nursing and Allied Health Literature, and reference lists of articles. Only studies of psychosocial interventions that used RCTs were included. Studies were eligible for inclusion if they included participants who received treatment (in an outpatient or community setting) and were 18 years of age or older and met diagnostic criteria for cannabis abuse or dependence by clinical assessment, or were at least near daily cannabis users or seeking treatment for their cannabis use.

A total of 23 RCTs were included in the review, which involved 4,045 participants. Of these studies, 15 were conducted in the United States, 2 studies were conducted in Germany, and 1 study each in Brazil, Canada, Ireland, and Switzerland. The average age of participants was 28.2 years. Of the total participants, the average use of cannabis at baseline was reported as 20.8 days of the past 30 days. Psychosocial interventions and therapies included in the meta-analysis were CBT, motivational enhancement therapy (MET), a combination of CBT and MET, contingency management, social support, mindfulness-based meditation, and drug education and counseling. Study results were pooled based on the comparisons between any psychosocial intervention versus inactive control (10 studies); any psychosocial intervention versus treatment as usual (3 studies); and any psychosocial intervention versus another intervention (9 studies).The CrimeSolutions review of this meta-analysis focused on the difference between the psychosocial intervention versus the inactive control.

The outcomes of interest included the use of cannabis (measured as self-reported use, including number of days, rate of abstinence, times per day), without or without confirmation by an objective means (such as urinalysis); the point-prevalence abstinence (which is the proportion of participants reporting continuous abstinence from treatment to final follow-up assessment); and severity of cannabis use disorder (measured by the symptoms of dependence). For continuous data, the effect size was calculated as standardized mean differences.