Exposure to medical marijuana advertising may influence attitudes toward and use of marijuana throughout adolescence
Previous research suggests adolescent exposure to medical marijuana (MMJ) advertising is associated with increased intention to use marijuana and marijuana use one year later. A new study expanded on this work by investigating the relationships among exposure to MMJ advertising in adolescence and marijuana use, future intentions to use marijuana, positive expectancies about marijuana, and marijuana-related harms over a seven-year period. Participants (N = 4,946) were aged 11 to 12 years at baseline and were followed until age 19. Participants were California middle school students who completed five waves of biannual surveys (74% to 90% follow-up rates), followed by four annual surveys (61% to 91% follow-up rates). Nearly 80% of participants completed two or more waves of surveys. The current study focused on waves 4 – 9. Measures included sociodemographic characteristics, intention to use marijuana in the next six months, endorsement of positive expectancies (i.e., using marijuana relaxes you), past 30-day marijuana use, and frequency of marijuana-related consequences, and exposure to MMJ advertisements. At wave 4 in 2010, 25% of respondents reported being exposed to at least one MMJ advertisement; by wave 9 in 2017, this figure was 70%. The authors used parallel process latent growth modeling in a structural equation modeling framework to examine the association between dual trajectories of MMJ advertising exposure over time with 1) trajectories for marijuana use, 2) intention to use marijuana, 3) positive marijuana expectancies, and 4) marijuana negative consequences. Results indicated the fit of all models was good to excellent. Mean exposure to MMJ advertising was positively associated with average marijuana use, average intent to use, and average consequences (all ps < 0.01). Higher rates of change in MMJ advertising exposure were significantly associated with higher rates of change for all four constructs listed above (all ps < 0.01). Among respondents who reported greater marijuana use, intent, and positive expectancies, there was a greater increase over time than their peers who reported lower levels of these constructs. The authors interpreted these results to indicate that exposure to MMJ advertising may influence expectancies, intent to use, and use throughout adolescence.
Take away: Among this sample of adolescents, exposure to advertising for medical marijuana was significantly positively associated with past-month marijuana use, intentions to use marijuana, positive marijuana expectancies, and marijuana-related harms across a seven-year period.
D’Amico, E.J., Rodriguez, A., Tucker, J.S., Pederson, E.R. & Shih, R.A. (2018). Planting the seed for marijuana use: Changes in exposure to medical marijuana advertising and subsequent adolescent marijuana use, perceptions, and consequences over seven years. Drug and Alcohol Dependence [published online ahead of print May 10, 2018] doi: 10.1016/j.drugalcdep.2018.03.031