Hooking Into the Internet to Combat Cannabis’ Hook

As the policies around cannabis change access and expand the population of regular cannabis users, we need broadly available and affordable interventions to combat increasing problematic use.  Technology-based interventions have been shown across multiple studies to be effective for different populations, with long-lasting effects on decreasing both cannabis and other substance use.


Approximately 4% of the worldwide population uses cannabis (183 million users worldwide). However, only approximately 12% of those with cannabis use disorder receive any treatment services. Increasing access to cannabis use disorder treatment may help partially offset rises in problematic use that accompanies easier access to cannabis, especially among teens and young adults. Computerized interventions offer the benefit being affordable and accessible remotely at all hours. Demonstrating the efficacy of computerized interventions for cannabis use on a larger scale across multiple studies and platforms can help validate an intervention that is well matched to the demographic preferences of many young adult cannabis users.


Authors performed a systematic review and meta-analysis.  The inclusion criteria were randomized controlled trials testing the efficacy of computer-delivered treatments vs control conditions on the frequency of cannabis use as the outcome.


Nine studies published through November 2015 were included in this meta-analysis (out of over 600 studies identified through their search), together totaling 2963 participants (1724 receiving computerized interventions and 1239 controls).

A secondary outcome of use of other substances (including cocaine, methamphetamines, opiates) was also performed, as well as subgroup analyses for length of follow-up, number of sessions, age group, type of control and type of analysis.  The efficacy measure used was the standardized mean difference (SMD) using 95% confidence intervals. This analysis focused on internet-based interventions and specifically excluded telephone-based and text-messaging based interventions.


1. The frequency of cannabis consumption was significantly decreased with computerized interventions as compared with controls. Combining nine studies that included almost 3000 cannabis-using participants, the participants randomized to computerized interventions showed a small but significant reduction in cannabis use as compared with controls (a standardized mean difference is  -0.19, with a 95% confidence interval of -0.26 to -0.11). Consumption was assessed both using questionnaires and urine toxicology.


Frequency of Cannabis Use Results


2. The frequency of other substance use was also decreased significantly with the computerized intervention. This was a secondary outcome using only three of the nine studies, totaling almost 500 cannabis users. The computerized interventions reduced other substance use (including cocaine, methamphetamines, opiates) significantly as compared with control conditions. The standardized mean difference is 0.27 (95% confidence interval of -0.46 to -0.008)

3. The efficacy was still evident for the different subgroups analyzed. The most remarkable part of this quantitative review of studies in this area is that the computerized interventions still showed a significant effect (they showed standardized mean differences <-0.13 with 95% confidence intervals less than 0) for the different subgroups. The interventions were effective whether the age of the participants was <20 or ≥20 years of age; whether the intervention was less than 6 months (SMD -0.19) or 6 months or longer (SMD -0.18). However, there was one exception: once there were less than 5 sessions of computerized intervention, it no longer made a reliable difference (the SMD of -0.11 now has a 95% CI of -0.27 to 0.05).

There were still significant effects whether the control condition was either waitlist or psycho-education, although the effect size was considerably smaller when the control was psycho-education. Thus, although the data was weighted towards one large study with a long 50-session intervention, the beneficial effects remained even whether other study designs were analyzed.


This study shows that even a low dose (5 sessions or more) of internet-based computerized interventions targeted to cannabis users can result in a significant (though modest) decrease in cannabis use frequency.  Furthermore, the efficacy is maintained for at least six months, and extends to other substance use beyond cannabis.  Given the broad accessibility of internet-based interventions and the low cost associated with this intervention, a broad dissemination of these interventions could have a large societal effect (a small effect over a large population) on decreasing cannabis and other substance use across locations and populations with more limited substance use treatment access.

  1. As with all meta-analyses, where many studies are being analyzed at once, the computerized interventions varied across a range of modalities (including computer-delivered personalized feedback computer-based intervention, computer-delivered CBT, clinician-assisted computer interventions) so different interventions are being pooled.
  2. Likewise, the control conditions vary significantly (waiting list, psycho-education, no intervention and assessment alone) but were all non-active interventions.
  3. Of the 9 studies included, the analysis was strongly influenced by one study (Tossmann et al 2011) that represents approximately 40% of the subjects receiving the computerized intervention, and which included 50 computerized sessions (virtually all of the other studies had 10 sessions or less). This limitation is partially offset by the subgroup analysis.
  4. The participants in these studies were cannabis users, not limited to those with cannabis use disorders. Hence, the effect may be more modest if focused on those with problematic use.  No data was provided giving a sense of the cannabis use patterns for the combined participants.


  • For individuals & families seeking recovery: The large number of cannabis users who may not warrant formal substance use disorder treatment may benefit significantly from technology-based interventions that deliver empirically-supported approaches through digital platforms. Though single sessions have not been shown to be effective, once five or more sessions have been completed, one can see sustained, albeit modest, decreases in cannabis use frequency even six months later. Other substance use is also decreased over time.  Thus, computerized interventions could be considered for all substances use, though its effectiveness as a solo treatment may be limited to less intensive patterns of use.
  • For scientists: More randomized controlled trials including an arm testing computerized interventions are needed for substance use in general and cannabis use in particular. Whether internet-based interventions are sufficiently effective for those with diagnosed substance use disorders has yet to be established broadly.  Whether they are best utilized as stand-alone interventions or augmenting clinic interventions needs to be studied. Regardless, their effectiveness on decreasing substance use looks promising. There may be a role for internet-based treatment not limited to any particular substance.
  • For policy makers: The potential beneficial effect of broad dissemination of internet-based substance use interventions is significant – a small effect across a large population still has a large population impact on reducing the level of substance use. Technology-based interventions are potentially low-cost, highly accessible approaches that bypass many of the barriers to care, including focusing on use rather than labeling use as problematic or warranting treatment.
  • For treatment professionals and treatment systems: Even beyond the substance use treatment field, perhaps the primary care medical system should start incorporating computerized interventions to decrease cannabis and other substance use. These interventions have already been shown to be effective for reducing smoking and for alcohol use.


Olmos, A., Tirado-Muñoz, J., Farré, M., & Torrens, M. (2017). The efficacy of computerized interventions to reduce cannabis use: A systematic review and meta-analysisAddictive behaviors.