Using Implementation Intentions to Reduce Cannabis Use

Randomized Controlled Trial of a Volitional Help Sheet in Cannabis Users

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.

Study Overview

• Status: Completed
• Conditions: Cannabis Use
• Intervention / Treatment: Behavioral: Volitional help sheet

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.

• Study Type: Interventional
• Enrollment (Actual): 311
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Manchester, United Kingdom, M13 9PL
    • The University of Manchester

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Frequent cannabis user (at least fortnightly)

Exclusion Criteria:

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: PREVENTION
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: SINGLE

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
ACTIVE_COMPARATOR: Control (volitional help sheet); Participants read a brief statement designed to encourage them to reduce their cannabis use ("We want you to plan to reduce your cannabis use"). Participants are presented with a table with two columns and twenty rows. Twenty 'high risk' situations (temptations) are presented in the left hand column and 20 appropriate responses (processes of change) are presented in the right hand column (see Armitage, 2008). Participants are told that identifying situations in which they were tempted to use cannabis and identifying ways to overcome those temptations had been shown to help people change their behaviour and are asked to tick critical situations/appropriate responses that might be useful to them.	Behavioral: Volitional help sheet; Participants are asked to choose from a list of strategies for avoiding cannabis use.
EXPERIMENTAL: Intervention (volitional help sheet); Participants read a brief statement designed to encourage them to reduce their cannabis use ("We want you to plan to reduce your cannabis use"). Participants are presented with a table with two columns and twenty rows. Twenty 'high risk' situations (temptations) are presented in the left hand column and 20 appropriate responses (processes of change) are presented in the right hand column (see Armitage, 2008). Participants are told that identifying situations in which they were tempted to use cannabis and identifying ways to overcome those temptations had been shown to help people change their behaviour. Implementation intentions are formed by linking critical situations with appropriate responses by choosing an appropriate response from a drop down menu for each critical situation.	Behavioral: Volitional help sheet; Participants are asked to choose from a list of strategies for avoiding cannabis use.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cannabis use reduction (amount)	Self-reported cannabis use -amount of cannabis (weight)	1 month
Cannabis use reduction (frequency)	Self-reported cannabis use - frequency of use (days per week)	1 month

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Self reported habit as measured by the automaticity subscale of the Self-Report Habit Index.	Self-reported habit (e.g., "Using cannabis is something I do automatically: strongly agree - strongly disagree).	1 month
Self reported action control as measured by the scale developed by Sniehotta et al (2011)	Self-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")	1 month
Self reported craving as measured by items from the mood and physical symptoms scale (MPSS)	self reported craving	1 month

Collaborators and Investigators

• Sponsor: University of Manchester
• Investigators: Principal Investigator: Lynsey Gregg, PhD, The University of Manchester

Publications and helpful links

General Publications

• 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.
• 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.
• 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.

Study record dates

Study Major Dates

• Study Start (ACTUAL): February 14, 2019
• Primary Completion (ACTUAL): November 30, 2020
• Study Completion (ACTUAL): November 30, 2020

Study Registration Dates

• First Submitted: December 20, 2018
• First Submitted That Met QC Criteria: February 15, 2019
• First Posted (ACTUAL): February 19, 2019

Study Record Updates

• Last Update Posted (ACTUAL): November 8, 2021
• Last Update Submitted That Met QC Criteria: November 5, 2021
• Last Verified: November 1, 2021

More Information

Terms related to this study

• Keywords: Cannabis; Risk reduction
• Additional Relevant MeSH Terms: Mental Disorders; Chemically-Induced Disorders; Substance-Related Disorders; Marijuana Abuse
• Other Study ID Numbers: 2018 5701

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No