Testing the Effects of Cann'App, a Digital Intervention for Cannabis Harm Reduction

Sponsor
Jacques Gaume
Study ID
NCT07157540
Status
Enrolling By Invitation

Conditions

  • Cannabis Use
  • Harm Reduction

Eligibility Criteria

Sex
ALL
Age
18 Years - N/A
Healthy Volunteers
Not accepted

Interventions

  • Personalized Feedback on Cannabis Protective Behavioral Strategies, Cannabis Use, Cannabis Expenditures, and Cannabis-Related Consequences (PF) — BEHAVIORAL
    PF comprises the following content: * Self-reported PBS questionnaire, personalized feedback on PBS, possibility to select strategies to start using or use more often, possibility to set a reminder to use PBS strategies. * Short questionnaire on cannabis use (frequency/number of hours under the influence) and normative feedback on participant's cannabis use as compared to people of same age and gender in the general population and among Cann-L participants. * Question on money spent for cannabis purchase, personalized feedback (total amount spent and corresponding number of grams of cannabis over one year), gamified gauge to picture potential yearly savings, reflection on how to use the saved money, and possibility to set a reminder for money saving objectives. * Questionnaire on cannabis-related consequences, feedback on the level of consequences met, question about which consequence(s) participant might want to think about, and possibility to set a reminder to think about consequences.
  • Imagining the Future Using Counterfactual Thinking and Episodic Future Thinking (IMAGIN) — BEHAVIORAL
    Two-task intervention including: 1. Counterfactual thinking: * Description of a recent negative situation related to cannabis use encountered by the participant * Identification of a preventive strategy that would have addressed this situation * Writing a sentence formatted as "If only +preventive strategy, then + description on how the specific past problem would have improved" * Assessment of participant's intention and confidence in using the preventive strategy * Imagining a future situation using this preventive strategy * Possibility to set a reminder of the preventive strategy. 2. Episodic future thinking: * Description of a significant positive event that might occur in the short-term (3 months) and that does not involve cannabis use * Assessment of the importance and enjoyment of this positive event * Encouragement to imagine it as vividly as possible * Suggestion to describe the positive event in detail and to write it down * Possibility to set a reminder of the positive event.
  • Behavioral Economics-Informed Exercises to Increase Motivation to Engage in Substance-Free Activities (SFAS) — BEHAVIORAL
    SFAS includes: * A questionnaire on how participant value different aspects of their life, and feedback on valued domains. * Two open-ended questions on short- and long-term life goals. * A questionnaire assessing time allocation (hours per week allocated to different activities, e.g. socializing, working, etc.), and personalized feedback including the time spent using substances and recovering from their effects. * Gamified exercise to imagine allocating time in a different way. * List of substance-free recreational activities in the region of Lausanne, with possibility to select activities on a "wish-list" including internet hyperlinks. * Possibility to set a reminder of the selected activities. * Single-item questionnaire on stress and mood, and feedback on stress and mood level. * Open-ended question on coping strategies currently used for stress and mood. * List of coping strategies that can be selected. * Possibility to set a reminder of stress/mood coping strategies.
  • Information — BEHAVIORAL
    Minimal intervention (Control Intervention), consisting of simple, text-only web pages containing information on cannabis effects and health-related risks, cannabis consumption modes, cannabis harm reduction and protective behavioral strategies, as well as hyperlinks to additional resources and online help.

Study Details

The goal of this clinical trial is to learn if a digital web application can prevent the risks related to cannabis use among adult regular cannabis users who are enrolled in a pilot trial for cannabis sales regulation conducted in Lausanne, Switzerland (i.e., Cann-L study) and have agreed that their data were used in other studies. The main question it aims to answer is: Do participants who have access to the intervention modules of the web application raise their use of protective behavioral strategies to lower cannabis-related risks? Researchers will compare the intervention modules to a control module (i.e., information on cannabis-related risks and harm reduction) to see if the web application works to prevent the risks related to cannabis use. They will also compare intervention modules across each other to see whether one works better than another. Participants will: * Create a user account in the web application * Access the web application using a laptop, tablet or smartphone * Use the web application as they wish throughout the duration of the study * Complete the regular Cann-L study questionnaires every six months, which will be used to measure their cannabis use and related risks.

Key Dates

First listed
Sep 5, 2025
Start date
Jan 5, 2026
Status verified
Jan 2026
Primary completion
Jul 31, 2027
Completion
Aug 31, 2027

Study Design

Enrollment
565 participants (estimated)
Allocation
RANDOMIZED
Intervention model
FACTORIAL
Primary purpose
PREVENTION

Arms

  • Experimental: Condition 1 - Personalized Feedback + Information
    Access to "Personalized Feedback" module (PF, Study Intervention) and "Information" module (Minimal, Control Intervention)
  • Experimental: Condition 2 - Imagine the future + Information
    Access to "Imagine the Future" module (IMAGIN, Study Intervention) and "Information" module (Minimal, Control Intervention)
  • Experimental: Condition 3 - Substance-Free Activities Session + Information
    Access to "Substance-Free Activities Session" module (SFAS, Study Intervention) and "Information" module (Minimal, Control Intervention)
  • Experimental: Condition 4 - Full Intervention + Information
    Access to the full intervention (PF+IMAGIN+SFAS) and "Information" module (Minimal, Control Intervention)
  • Active Comparator: Condition 5 - Information only (Control)
    Access to "Information" module (Minimal, Control Intervention)

Primary Outcome Measure

Frequency of Protective Behavioral Strategies for Marijuana Use as Measured by the PBSM-17 Short Form Scale [ Time Frame: This outcome will be assessed at 1- and 7-month follow-up. ]

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