Testing the Effects of Cann'App, a Digital Intervention for Cannabis Harm Reduction
NCT ID: NCT07157540
Last Updated: 2026-01-12
Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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ENROLLING_BY_INVITATION
NA
565 participants
INTERVENTIONAL
2026-01-05
2027-08-31
Brief Summary
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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.
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Detailed Description
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Conditions
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Study Design
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RANDOMIZED
FACTORIAL
PREVENTION
TRIPLE
Study Groups
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Condition 1 - Personalized Feedback + Information
Access to "Personalized Feedback" module (PF, Study Intervention) and "Information" module (Minimal, Control Intervention)
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.
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.
Condition 2 - Imagine the future + Information
Access to "Imagine the Future" module (IMAGIN, Study Intervention) and "Information" module (Minimal, Control Intervention)
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.
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.
Condition 3 - Substance-Free Activities Session + Information
Access to "Substance-Free Activities Session" module (SFAS, Study Intervention) and "Information" module (Minimal, Control Intervention)
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.
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.
Condition 4 - Full Intervention + Information
Access to the full intervention (PF+IMAGIN+SFAS) and "Information" module (Minimal, Control Intervention)
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.
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 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.
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.
Condition 5 - Information only (Control)
Access to "Information" module (Minimal, Control Intervention)
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.
Interventions
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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.
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 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.
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.
Eligibility Criteria
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Inclusion Criteria
* being adult (\>18 years old),
* having current cannabis use (i.e., use at least once a month over the last 6 months)
* living in the city of Lausanne. To enter the study, they complete an entry assessment verifying their age and proof of residence, and confirming that they have current cannabis use.
Exclusion Criteria
* being pregnant or breastfeeding,
* having a health condition contraindicating the use of cannabis (e.g., severe psychiatric disorder).
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.
* not providing informed consent to participate in sub-studies, including studies on prevention measures,
* not providing informed consent to participate in the present study.
18 Years
ALL
No
Sponsors
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Swiss National Science Foundation
OTHER
Apptitude
UNKNOWN
Addiction Switzerland
UNKNOWN
Jacques Gaume
OTHER
Responsible Party
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Jacques Gaume
PhD scientist
Principal Investigators
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Jacques Gaume, PhD
Role: PRINCIPAL_INVESTIGATOR
University of Lausanne Hospitals
Locations
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Lausanne University Hospital
Lausanne, Vaud Canton, Switzerland
Countries
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Other Identifiers
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10001E_220072
Identifier Type: OTHER_GRANT
Identifier Source: secondary_id
2025-00428
Identifier Type: -
Identifier Source: org_study_id
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