Personalized Feedback Intervention to Reduce Risky Cannabis Use.

The purpose of this project is to determine whether participants who receive a personalized feedback report and educational materials about risky cannabis use will be less likely to report risky cannabis use at follow-up compared to participants who only received educational materials.

This project aims to reduce risky cannabis use among those with less severe cannabis use, most of whom will never seek formal treatment. All of the participants will receive educational material regarding risky cannabis use and its prevention. Half of the participants will also be assigned by chance to receive a personalized feedback report. The investigators hypothesize that: Participants who receive the full personalized feedback intervention will be less likely to report risky cannabis use at 3- and 6-month follow-ups compared to participants who receive educational materials only (Primary Hypothesis). Participants who receive the full personalized feedback intervention will report greater reductions in their perceptions of how much others use cannabis at a 3-month follow-up compared to participants who receive educational materials only. Reductions in perceptions of how much others use cannabis at 3-month follow-up will be positively associated with reduction in the participant's risky cannabis use at 6-month follow-up. A 2-arm parallel group randomized controlled trial will be conducted to test these hypotheses with follow-ups occurring at 3 and 6 months after randomization. Online media advertisements will be used to recruit people currently using cannabis. The advertisements will be placed across Canada using locations found successful in previous trials to rapidly recruit participants (e.g. Google AdWords).

This arm is provided personalized feedback concerning their cannabis use in addition to educational materials about risky cannabis use.

A report comparing the participant's cannabis use to peer usage, and summarizing problems experienced and risk associated with future use.

Canada's Lower-Risk Cannabis Use Guidelines prepared by the Centre for Addiction and Mental Health which outlines methods to help reduce health risks associated with cannabis use.

Change in cannabis subscale scores from baseline. Scores are calculated as a sum of six items and totals can range from 0 to 39 with higher scores indicating greater risk.

Change in participant's perceptions of how much their peers (same age and gender) use cannabis. Measured as a percentage of peers that do not use cannabis (%) and a 5-points Likert scale, 0 "Never" to 5 "Daily or Almost daily" of frequency of peer use

Inclusion Criteria: Score of 4 or more on the Alcohol, Smoking, and Substance Involvement Screening Test, Cannabis subscale (ASSIST) Exclusion Criteria: Being under 18 years of age

Description Information about research at the Centre for Addiction and Mental Health, Canada's largest mental health and addiction teaching hospital, fully affiliated with the University of Toronto, and a PAHO/WHO Collaborating Centre