Comprehensive Interventions for Reducing Cannabis Use

Judit Tirado-Muñoz; Juan I. Mestre-Pintó; Magí Farré; Francina Fonseca; Marta Torrens


Curr Opin Psychiatry. 2018;31(4):315-323. 

In This Article

Advances in Psychosocial Interventions for Cannabis use

We present findings divided in two categories: therapist-assisted and computerized interventions.

Therapist-assisted Interventions

A Cochrane collaboration review on psychosocial interventions for CUD[14] found support to an intensive intervention (more than four sessions), combining motivational enhancement therapy (MET) and cognitive behavioural therapy (CBT) intervention with abstinence-based incentives in reducing cannabis use in the short term. The review provided effect sizes of the intervention on the various outcome measures. By outcomes, those receiving psychosocial intervention reported using cannabis on fewer days mean difference 5.67, 95% CI 3.08–8.26), fewer symptoms of dependence [standard mean difference (SMD) 4.15, 95% CI 1.67–6.63], fewer cannabis-related problems (SMD 3.34, 95% CI 1.26–5.42) and fewer joints per day (SMD 3.55, 95% CI 2.51–4.59) at short-term follow-up compared with inactive controls.

In addition, we identified four studies assessing therapist-assisted interventions. A cluster randomized controlled trial involving 77 trained general practitioners (GPs) and 262 participants was conducted.[19] The brief intervention, based on feedback, responsibility, advice, menu, empathy and, self-efficacy model consisted of an interview conducted by the GPs to retrieve feedback from the participant, which included participants' consumption quantity and its consequences, as well as their personal responsibility to change. GPs advised on moderation use techniques and defined a selection of alternative change options together with participants. The control group received routine care after assessing participant's cannabis use. The primary outcome, number of joints per month at 1 year, was compared between groups; secondary outcomes were intermediate consumed joints per month as well as the use of cigarettes and alcohol. Subgroup analyses were conducted. Although overall results show no long-term (1-year follow-up) effectiveness of the brief intervention in comparison with control intervention, it proved significantly effective among nondaily smokers (number of joints: 3 vs. 10; P = 0.01). Authors also found significant differences in favour of the intervention among younger cannabis users 6 months postintervention (number of joints: 12.5 vs. 20, P = 0.04).

Another study examined the effectiveness of a 20-min motivational enhancement intervention among 46 urban high-risk cannabis users in a 6 month RCT.[20] The intervention addressed five clinical issues: rapport, acceptance, collaboration, reflections and nonconfrontation and was divided in four sections of 5 min (graphic form presentation of substance use feedback, substance use likes/dislikes and discrepancies discussion, peer network information and graphical feedback introduction and finally a change plans summary). The results of this secondary analysis based on the cannabis use item of the Youth Risk Behaviour Survey found some significant effects in favour of the intervention (35.9% probability of being abstinent compared with a 13.2% in control group), supporting the use of peer network counselling (PNC) to reduce cannabis use among adolescents classified as heavy users.

The following two studies focused on cannabis as well as other substances use. An RCT involving nonseeking treatment, cannabis users and young adults was conducted to assess the efficacy of a motivational intervention.[21] Participants reported at least monthly binge drinking and at least weekly marijuana use. The intervention focused on emerging adulthood' themes and the relationship of participants with substance use (two main sessions). Three more check-up sessions were part of the tested intervention. Control condition participants received general health education. The tested intervention did not show any improvement on alcohol binge drinking outcomes (P = 0.37), marijuana use (P = 0.07) or dual use (P = 0.55) relative to a control condition.

Finally, an RCT of a brief intervention for alcohol and other drugs of abuse in primary healthcare was identified.[22] Associated with the Alcohol Smoking and Substance Involvement Screening Test, the intervention was compared with a control condition. The brief intervention did not prove to be more effective when compared with an informational pamphlet on alcohol, cannabis and cocaine use reduction.

Computerized Interventions

Two reviews and meta-analysis of computerized interventions for reducing cannabis use have been published summarizing clinical trials results in the last year.[15,16] One of them focused on internet-delivered interventions for other substance use besides cannabis, and other health problems such as mental health, childhood health problems, diet and physical activity and so on.[16] The second one focused only on computerized interventions to reduce cannabis use[15] even though the use of other substances was also assessed as an outcome. They also found that efficacy on reducing cannabis use increased with the number of sessions (≥ five sessions). Both found that computerized interventions reduced the frequency of cannabis[15,16] and other substance use.[15]

Furthermore, a primary study on computerized intervention has been identified.[23] It was a two-arm randomized trial (with no control group) aimed at testing the efficacy of brief vs. extended personalized infographic feedback in an online intervention. At the beginning, same demographics and recent cannabis use questions were asked to two participants in both conditions. The brief and extended personalized feedback included: definitions of cannabis dependence and its diagnose criteria, past month cannabis use, drug and alcohol use services contact information and feedback of participants' motivations for using cannabis. In addition, feedback of the extended version included suggestions to reduce consumption based on motivations, reasons for using, severity of cannabis use, related harms and wished treatment. Participants should meet at least one cannabis abuse or dependence criteria according to Diagnostic and Statistical Manual of Mental Disorders-IV.[24] At 1-month follow-up, both versions (brief and extended) showed significant reductions in past month quantity and frequency of cannabis use, while only brief personalized feedback decreased severity dependence (P = 0.002; r = -0.31). The study from Copeland et al.[23] had some limitations, mostly related to the lack of control group, the use of self-reported data to assess outcomes and the short-term effects evaluation (1 month).