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Using Implementation Intentions to Reduce Cannabis Use

Randomized Controlled Trial of a Volitional Help Sheet in Cannabis Users

Status
Completed
Phases
NA
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT03845842
Enrollment
311
Registered
2019-02-19
Start date
2019-02-14
Completion date
2020-11-30
Last updated
2021-11-08

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Cannabis Use

Keywords

Cannabis, Risk reduction

Brief summary

The study will recruit frequent users of cannabis (defined at least fortnightly use) and randomize them either to: (1) form implementation intentions by linking situations in which they are tempted to use cannabis with strategies to avoid using cannabis in those situations by using a volitional help sheet, or (2) to consider the situations in which they are tempted to use cannabis alongside possible strategies to avoid using it as presented in the volitional help sheet but not to form implementation intentions. The effects on self-reported cannabis use will be assessed 1 month post-intervention. Predictors of cannabis reduction will also be examined.

Detailed description

Design: This study will use questionnaires to assess participants cannabis habits (frequency and amount of use) and then employ planning strategies to help them quit. Follow up questionnaires will be used to ascertain the success of planning on reduction in cannabis use. Sample Size: We plan to recruit a minimum of 60 participants in each condition (120 total) but aim to collect data from as many participants as possible. Recruitment: To participate in this study a person must be over the age of 18 and a frequent user of cannabis. The study will be advertised online on social media platforms. Procedure: Potential participants will follow an online link to a briefing sheet that provides information about the study. The sheet will also inform participants that they do not have to complete the questionnaire and that they can withdraw from the study at any time without giving a reason. Once they have read the briefing sheet and generated their personal identity code, as instructed, they will complete the questionnaire online. A month after the participants have completed the initial questionnaire they will receive a link to a follow-up questionnaire via email. Email addresses will be stored separately to study data and will be destroyed once the follow up phase has completed and their involvement in the study ends. Outcomes and Analysis: The main purpose of this study is to explore the role of planning in encouraging people to reduce cannabis use. Quantitative analysis will be conducted to assess the effects of planning on cannabis use reduction. The investigators expect to find that planning is effective in helping people reduce their use.

Interventions

Participants are asked to choose from a list of strategies for avoiding cannabis use.

Sponsors

University of Manchester
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
SINGLE (Investigator)

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes

Inclusion criteria

* Frequent cannabis user (at least fortnightly)

Exclusion criteria

* Younger than 18 years of age * Infrequent / no cannabis use (less than fortnightly)

Design outcomes

Primary

MeasureTime frameDescription
Cannabis use reduction (amount)1 monthSelf-reported cannabis use -amount of cannabis (weight)
Cannabis use reduction (frequency)1 monthSelf-reported cannabis use - frequency of use (days per week)

Secondary

MeasureTime frameDescription
Self reported habit as measured by the automaticity subscale of the Self-Report Habit Index.1 monthSelf-reported habit (e.g., Using cannabis is something I do automatically: strongly agree - strongly disagree).
Self reported action control as measured by the scale developed by Sniehotta et al (2011)1 monthSelf-reported action control (e.g., During the last week I often had my intention to reduce my cannabis use on my mind: strongly disagree-strongly agree)
Self reported craving as measured by items from the mood and physical symptoms scale (MPSS)1 monthself reported craving

Countries

United Kingdom

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026