Cannabis use is a significant problem among Australian adolescents. There is evidence suggesting that substance use interventions for adolescents must target immediate affective responses to thoughts of using the substance. Therefore, graphic or otherwise emotion provoking warning images may be effective in deterring adolescent substance use.
Adolescents aged 15-18 were randomly assigned to receive the intervention program, or to a control condition. Cannabis use was assessed before the intervention and at a six-month follow-up. Adolescents assigned to the intervention condition rated the images in terms of their perceived effectiveness.
The study recently completed recruitment of 177 participants using a cluster-randomised design. 134 completed the six-month follow-up assessment. Results show the intervention group reduced their past month (p = .02) and past week (p = .03, 1 tailed) days of cannabis use, as well as their past week quantity of cannabis use (p = .047, 1 tailed), significantly more than did the control group. While the percentage of cannabis users in the study was too small to conduct significance tests relating to past-month abstinence, there was a 30.5% reduction in participants reporting use in the past month in the control group compared with a 66.3% reduction in the intervention group. Participants found images of physical health effects more deterring than images of negative social and psychological effects.
Findings were presented at the 2012 National Cannabis Conference, and a journal article describing the research findings has been submitted for publication.
These findings provide an initial indication that warning imagery has potential as a prevention initiative for cannabis use.