Clinical trial NCT03845842: Using Implementation Intentions to Reduce Cannabis Use
Official title: Randomized Controlled Trial of a Volitional Help Sheet in Cannabis Users
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Cannabis Use
Keywords: Cannabis
Risk reduction
Lead sponsor: University of Manchester
Sponsor class: OTHER
First posted: 2019-02-19
Enrollment: 311
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: PREVENTION

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.

Eligibility criteria: Inclusion Criteria:

* Frequent cannabis user (at least fortnightly)

Exclusion Criteria:

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

Primary outcomes:
measure: Cannabis use reduction (amount)
timeFrame: 1 month
measure: Cannabis use reduction (frequency)
timeFrame: 1 month
Secondary outcomes:
measure: Self reported habit as measured by the automaticity subscale of the Self-Report Habit Index.
timeFrame: 1 month
measure: Self reported action control as measured by the scale developed by Sniehotta et al (2011)
timeFrame: 1 month
measure: Self reported craving as measured by items from the mood and physical symptoms scale (MPSS)
timeFrame: 1 month
Other outcomes:
Locations:
city: Manchester
country: United Kingdom
facility: The University of Manchester
Study officials:
affiliation: The University of Manchester
name: Lynsey Gregg, PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Sniehotta FF, Nagy G, Scholz U, Schwarzer R. The role of action control in implementing intentions during the first weeks of behaviour change. Br J Soc Psychol. 2006 Mar;45(Pt 1):87-106. doi: 10.1348/014466605X62460.
citation: Gardner B, Abraham C, Lally P, de Bruijn GJ. Towards parsimony in habit measurement: testing the convergent and predictive validity of an automaticity subscale of the Self-Report Habit Index. Int J Behav Nutr Phys Act. 2012 Aug 30;9:102. doi: 10.1186/1479-5868-9-102.
citation: West R, Hajek P. Evaluation of the mood and physical symptoms scale (MPSS) to assess cigarette withdrawal. Psychopharmacology (Berl). 2004 Dec;177(1-2):195-9. doi: 10.1007/s00213-004-1923-6. Epub 2004 Jun 4.