An interventional study of Personalized Feedback on Cannabis Protective Behavioral Strategies, Cannabis Use, Cannabis Expenditures, and Cannabis-Related Consequences (PF) and Imagining the Future Using Counterfactual Thinking and Episodic Future Thinking (IMAGIN) in Cannabis Use and Harm Reduction, sponsored by Jacques Gaume. Enrolling by invitation at 1 site in Switzerland. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-01-12.
Sponsored by Jacques Gaume · Not applicable, Interventional, and Prevention
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:
115 studies on the registry are indexed under Harm Reduction; 39 are open to participants now.
This study's planned enrollment of 565 is above the median of 139 across 92 interventional studies indexed under Harm Reduction.
Browse Harm Reduction studies →This is the only study on the registry with Jacques Gaume as lead sponsor.
Counted across the registry records on this site, refreshed daily.
Inclusion Criteria:
Inclusion criteria in Cann-L study are:
Exclusion Criteria:
The consent to participate in the Cann-L parent trial comprises an option to be contacted to participate in sub-studies, including studies on prevention measures. All participants having accepted to be so contacted will be proposed to participate in the present study.
Therefore, additional exclusion criteria for the present study include:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Access to "Personalized Feedback" module (PF, Study Intervention) and "Information" module (Minimal, Control Intervention)
Behavioral: Personalized Feedback on Cannabis Protective Behavioral Strategies, Cannabis Use, Cannabis Expenditures, and Cannabis-Related Consequences (PF) · Behavioral: Information
Access to "Imagine the Future" module (IMAGIN, Study Intervention) and "Information" module (Minimal, Control Intervention)
Behavioral: Imagining the Future Using Counterfactual Thinking and Episodic Future Thinking (IMAGIN) · Behavioral: Information
Access to "Substance-Free Activities Session" module (SFAS, Study Intervention) and "Information" module (Minimal, Control Intervention)
Behavioral: Behavioral Economics-Informed Exercises to Increase Motivation to Engage in Substance-Free Activities (SFAS) · Behavioral: Information
Access to the full intervention (PF+IMAGIN+SFAS) and "Information" module (Minimal, Control Intervention)
Behavioral: Personalized Feedback on Cannabis Protective Behavioral Strategies, Cannabis Use, Cannabis Expenditures, and Cannabis-Related Consequences (PF) · Behavioral: Imagining the Future Using Counterfactual Thinking and Episodic Future Thinking (IMAGIN) · Behavioral: Behavioral Economics-Informed Exercises to Increase Motivation to Engage in Substance-Free Activities (SFAS) · Behavioral: Information
Access to "Information" module (Minimal, Control Intervention)
Behavioral: Information
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.
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.
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.
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.
Frequency of Protective Behavioral Strategies for Marijuana Use as Measured by the PBSM-17 Short Form Scale
This outcome will be measured using the Protective Behavioral Strategies for Marijuana Use (PBSM-17) Short Form scale, a self-reported 17-item questionnaire measuring the frequency of PBS for cannabis use on a 6-point Likert scale ranging from 1 (never) to 6 (always).
Time frame: This outcome will be assessed at 1- and 7-month follow-up.
Cannabis Use Frequency
Cannabis Use Frequency will be measured using a single item asking "During the past 30 days, on how many days did you use cannabis?"
Time frame: This outcome will be measured at 1- and 7-month follow-up.
Number of Hours High on a Typical Day
The number of hours under influence will be measured using a single item asking "How many total hours were you high on a typical day when you had been using cannabis?"
Time frame: This outcome will be measured at 1- and 7-month follow-up.
Cannabis Use Disorder Severity as Measured by CUDIT-R
This outcome will be measured using the Cannabis Use Disorder Identification Test - Revised (CUDIT-R), a self-reported 8-items questionnaire (i.e., question 1-7 are scored on a 0-4 scale, and question 8 is scored 0, 2, or 4). Scores of 8 or more indicate hazardous cannabis use, while scores of 12 or more indicate a possible cannabis use disorder for which further intervention may be required.
Time frame: This outcome will be measured at 1- and 7-month follow-up.
Cannabis Purchase Task
This outcome will be used to measure behavioral economics indices of cannabis demand. Participants will be asked to report hypothetical cannabis consumption in a scenario at escalating prices.
Time frame: This outcome will be assessed at 1- and 7-month follow-up.
Source of Cannabis Supply
This outcome will be measured for each cannabis product (herbal/marijuana, resin/hashish, oral oil, e-liquids, concentrates, edibles, other) by reporting the frequency of supply in a) Cann-L study dispensary, b) other external sources (e.g., acquaintances, on the street, social networks, darknet).
Time frame: This outcome will be assessed at 1- and 7-month follow-up.
Alternatives to Smoking Cannabis
The frequency of use of four main consumption modes (smoking, vaping/dabbing, absorbing, and edibles) will be measured using four corresponding cursors for which the total should be 100%.
Time frame: This outcome will be assessed at 1- and 7-month follow-up.
Purchase of Cannabis with Lower THC Ratio
This outcome will be computed based on individual sales data from Cann-L study dispensary.
Time frame: This outcome will be assessed at 1- and 7-month follow-up.
Simultaneous Use of Cannabis and Other Substances
This outcome will be assessed by two items measuring the frequency of simultaneous use, one for alcohol and one for other illegal drugs.
Time frame: This outcome will be assessed at 1- and 7-month follow-up.
Plan to share: Yes — The data collected for this study may be reused and/or transmitted for other studies (including abroad), always in coded form (i.e., deidentified dataset). For each instance of reuse in another study, a data transfer agreement will need to be established.
Time frame: Beginning immediately after the publication of results and ending 20 years after study termination.
Access criteria: A formal request should be submitted to the Principal investigator and a data sharing agreement must be signed.
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