Measuring Within-Individual Cannabis Reduction in Clinical Trials: A Review of the Methodological Challenges

Urgent need for treatment addressing co-use of tobacco and cannabis: An updated review and considerations for future interventions

BACKGROUND

There are no clinical practice guidelines addressing the treatment of tobacco-cannabis co-use and a dearth of studies to inform treatment for co-use. This narrative review aims to (1) summarize promising intervention components used in published co-use treatment studies, (2) describe key gaps and emerging issues in co-use, and (3) provide recommendations and considerations in the development and evaluation of co-use interventions.

METHODS

We conducted a literature search in June 2024 across several databases to update previous reviews on tobacco-cannabis co-use treatment. We found 9 published intervention studies that specifically addressed treatment for both substances. Data from these studies were manually extracted and summarized.

RESULTS

Most of the 9 included studies (1) focused on acceptability and/or feasibility, (2) provided both psychosocial/behavioral and pharmacotherapy intervention components, (3) were conducted in adults, and (4) were delivered in-person, with some having digital asynchronous components, for a 5-to-12-week duration. The most common psychosocial/behavioral strategies used were Cognitive Behavioral Therapy, Motivational Interviewing, and Contingency Management; while the most common pharmacotherapy was Nicotine Replacement Therapy. There was no evidence of compensatory use of tobacco or cannabis when providing simultaneous treatment for both substances.

CONCLUSIONS

The literature to date provides support for well-integrated multi-component interventions of psychosocial/behavioral and pharmacotherapy strategies for co-use treatment. This review reinforces an urgent need for treatments targeting tobacco and cannabis co-use. Future interventions should address key gaps, including co-use of vaporized products among youth and young adults, tailored interventions for priority populations, and digital applications to increase reach and advance health equity.

Tobacco, Alcohol, and Drug Use Among Young Adults with Serious Mental Illness

To inform early intervention, this study describes correlates of substance use among young people with serious mental illness (SMI) enrolled in integrated care in community mental health settings. 227 adults ages 18-35 were assessed for clinical characteristics and substance use. Logistic regressions were used to describe relationships between substance use and participant characteristics. Over a third (38.9%) reported daily cannabis, 15.9% past month other illicit drug, 13.5% frequent/heavy alcohol and 47.4% any of these; 50.2% reported daily tobacco smoking and 23.3% current vaping. Daily cannabis and tobacco were the most common combination. Alcohol, drug, and cannabis with tobacco were associated with higher mental health symptoms but not with emergency room or hospital utilization. Cannabis and other substance use was common and associated with higher symptoms but not with greater hospital utilization, suggesting that early intervention could prevent long-term negative consequences.

Identifying brief intervention factors to improve cannabis related outcomes in adolescents and young adults: A systematic review of sample characteristics and intervention components

INTRODUCTION

Prior systematic and meta-analytic reviews observed mixed evidence for the efficacy of cannabis brief interventions (BIs). Inconsistent support for cannabis BIs may be the result of intersecting methodological factors, including intervention structure and content, participant eligibility criteria, and outcome assessment measures. The current systematic review of cannabis BI studies narratively synthesizes these data to guide intervention development decision-making in future cannabis BI studies (PROSPERO CRD42022285990).

METHODS

We searched PubMed/MEDLINE, PsycINFO, and CINAHL databases in January 2022 and again in June 2023 to capture newly published studies. Studies were included if they were a randomized trial, enrolled adolescents (13-17) and/or young adults (18-30), specified cannabis use and/or problems inclusion criteria, and evaluated a cannabis BI (defined as ≤4 sessions). We extracted and synthesized data on intervention characteristics (e.g., components, length/duration, modality), cannabis inclusion criteria and recruitment setting, baseline cannabis use descriptives and treatment-seeking status, and outcome assessment measures to discern if/how they may intersect to determine intervention efficacy. The Cochrane Risk of Bias Tool 2 assessed study quality.

RESULTS

Our search resulted in a final sample of 25 study records including 4094 participants. Recruitment setting seemed to provide an influential backdrop for how well inclusion criteria determined baseline cannabis use level, as well as for the type/length of the BI evaluated. Motivational interviewing (MI) and personalized feedback (PF) were the most frequently used BI components overall; however, some differences were observed in the proportion of BIs with reported intervention effects using MI vs. PF. Frequency of use days was the most commonly used outcome measure, although this may not be the most sensitive measure for assessing cannabis BI efficacy.

CONCLUSIONS

Our systematic review indicates that cannabis BI studies require greater precision in their design, giving special attention to matching the content and structure of the BI to the needs of the target population and selecting outcomes commensurate to the goals of the BI and the target population to more accurately reflect the efficacy of the BI. However, consistent with prior reviews, all included studies demonstrated at least some concerns for risk of bias, and most were at high risk.

Exploring survey methods for measuring consumption quantities of cannabis flower and concentrate products

Background: Researchers need accurate measurements of cannabis consumption quantities to assess risks and benefits. Survey methods for measuring cannabis flower and concentrate quantities remain underdeveloped.Objective: We examined "grams" and "hits" units for measuring flower and concentrate quantities, and calculating milligrams of THC (mgTHC).Methods: Online survey participants (n = 2,381) reported preferred unit (hits or grams), past-week hits and grams for each product, and product %THC. Quantile regression compared mgTHC between unit-preference subgroups. Hits-based mgTHC calculations assumed a universal grams-per-hit ratio (GPHR). To examine individualized GPHRs, we tested a "two-item approach," which divided total grams by total hits, and "one-item approach," which divided 0.5 grams by responses to the question: "How many total hits would it take you to finish 1/2 g of your [product] by [administration method]?"Results: Participants were primarily daily consumers (77%), 50% female sex, mean age 39.0 (SD 16.4), 85% White, 49% employed full-time. Compared to those who preferred the hits unit, those who preferred the grams unit reported consuming more hits and grams, higher %THC products, and consequently, larger median mgTHC (flower-hits mgTHC: 32 vs. 91 (95%CI: 52-67); flower-grams mgTHC: 27 vs. 113 (95%CI: 73-95); concentrate-hits mgTHC: 29 vs. 59 (95%CI: 15-43); concentrate-grams mgTHC: 61 vs. 129 (95%CI: 43-94)). "Two-item" and "one-item" approach GPHRs were similar and frequently 50% larger or smaller than the universal GPHR.Conclusion: Allowing respondents to choose "hits" or "grams" when reporting cannabis quantities does not compromise mgTHC estimates. A low-burden, one-item approach yields individualized "hit sizes" that may improve mgTHC estimates.

Implementation and Preliminary Evaluation of a 12-Week Cognitive Behavioural and Motivational Enhancement Group Therapy for Cannabis Use Disorder

Background

The purpose of this paper is to provide a preliminary evaluation of treatment outcomes, retention and client satisfaction following a 12-week combined cognitive behavioural therapy (CBT) and motivational enhancement therapy (MET) group treatment for cannabis use disorder (CUD) delivered in an outpatient setting. Implementation of the program is also described.

Methods

A retrospective observational cohort study was conducted using data collected from medical records and self-report assessments. Participants were treatment-seeking cannabis users at the Centre for Addiction and Mental Health, Toronto. Cannabis use, cannabis-related problems, craving, withdrawal symptoms, self-efficacy for remaining abstinent, depression and anxiety were assessed pre- and post-treatment. Treatment retention was calculated by inspecting clinic attendance records, and client satisfaction was evaluated using an anonymous feedback survey. Potential predictors of treatment outcomes and retention were investigated in exploratory analyses.

Results

Cannabis use was lower and days of abstinence higher post-treatment (vs pre-treatment). Post-treatment improvements in cannabis-related problems, craving, withdrawal symptoms, self-efficacy and mood were also observed. Completion of group treatment (⩾75% of sessions attended) was 57% and moderate levels of treatment satisfaction were reported.

Conclusions

This study provides preliminary evidence that a 12-week combined CBT and MET treatment for cannabis use disorder delivered in a novel group setting improves cannabis use outcomes. Potential predictors of reduced cannabis use and retention were identified. Future controlled studies are warranted, and strategies for increasing retention should be explored.

Measuring recent cannabis use across modes of delivery: Development and validation of the Cannabis Engagement Assessment

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The CEA is consistent with expert-recommended guidelines for quantifying cannabis use.

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The CEA is representative of current patterns of recreational cannabis engagement.

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Estimates of cannabis use show strong associations with the timeline followback method.

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The CEA shows good test–retest reliability over a one-week period.

Introduction

Methods of cannabis engagement have proliferated in recent years, which many self-report measures do not adequately capture. There is a clear need for self-report measures that capture current patterns of cannabis use across a range of methods, and that can be used to track changes over time. The current study developed the Cannabis Engagement Assessment (CEA), a self-report measure of past month cannabis use across dry flower, concentrate, and edible products.

Methods

A sample of 349 participants from the undergraduate student population and broader community were recruited. To examine convergent validity of the CEA, participants completed measures of cannabis engagement, cannabis misuse, and use-related problems. To assess divergent validity, participants also completed measures of depression and alcohol use problems. Criterion and test–retest reliability were examined in a subset of 65 participants who re-completed the CEA and a timeline follow-back interview (TLFB).

Results

Indicators of cannabis use frequency and quantity showed good convergence with measures of cannabis use patterns, problematic engagement, and cannabis use-related problems. Divergent validity of the CEA was supported by lower associations with alcohol use problems and depression symptoms. The CEA also showed good test–retest reliability and convergence with estimates of frequency and quantity of cannabis use from the TLFB.

Conclusions

The CEA is a viable self-report measure of cannabis use that is representative of current patterns of recreational cannabis engagement. Its focus on cannabis use in the preceding 30 days also lends itself to measuring changes in use over time.

Treatment Implications Associated with Cannabis and Tobacco Co-Use

PURPOSE OF THE REVIEW

The goal of this article is to summarize the treatment-focused literature on cannabis and tobacco co-use and the treatment implications of co-use. This review will focus on: 1) the impact of co-use on cessation outcomes, 2) compensatory use/substitution of the non-treated substance among co-users, and 3) treatment interventions to address co-use. This article will highlight the limitations to co-use captured in the literature and offer considerations and directives for co-use research and treatment moving forward.

RECENT FINDINGS

The degree to which co-use affects cessation for a single, targeted substance remains in question, as the literature is largely mixed. Cannabis treatment trials are better equipped to answer these questions given that they do not typically exclude tobacco users. While the relationship between tobacco use and poorer cannabis outcomes appears to have some evidence, the reverse relationship (cannabis use affecting tobacco outcomes) is not consistently supported.

SUMMARY

The co-use of cannabis and tobacco and its impact on single substance cessation and/or compensatory substance use during cessation is generally overlooked in treatment trials, while interventions to address both substances are rare. Capturing co-use adds burden for researchers, clinicians, and participants, but is warranted given the prevalence of co-use and a rapidly changing cannabis and tobacco regulatory environment, which may further complicate co-occurring substance use. Co-users are a heterogeneous population; trials focused on co-users, in addition to better data capture and consistent terminology, will aid in an understanding of nuanced patterns of co-use critical to inform treatment interventions.