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

Summary

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.

Conditions

• Cannabis Use
• Harm Reduction

Interventions

BEHAVIORAL

Personalized Feedback on Cannabis Protective Behavioral Strategies, Cannabis Use, Cannabis Expenditures, and Cannabis-Related Consequences (PF)

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.

BEHAVIORAL

Imagining the Future Using Counterfactual Thinking and Episodic Future Thinking (IMAGIN)

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

Behavioral Economics-Informed Exercises to Increase Motivation to Engage in Substance-Free Activities (SFAS)

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.

BEHAVIORAL

Information

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.

Sponsors & Collaborators

• Swiss National Science Foundation

  collaborator OTHER

• Apptitude

  collaborator UNKNOWN

• Addiction Switzerland

  collaborator UNKNOWN

• Jacques Gaume

  lead OTHER

Principal Investigators

• Jacques Gaume, PhD · University of Lausanne Hospitals

Study Design

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

TRIPLE

Model

FACTORIAL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2026-01-05

Primary Completion

2027-07-31

Completion

2027-08-31

Countries

• Switzerland

Study Locations