Predictors of marijuana vaping onset and escalation among young adults

Background: Little is known about factors that influence marijuana vaping among young people. We examined cigarette, e-cigarette and marijuana use experiences, social network characteristics and exposure to direct e-cigarette marketing as predictors of marijuana vaping initiation and escalation. Methods: One-year prospective data were collected between 2017 and 2019 from 2327 young adults (Mean age = 21.2; SD = 2.1; 54 % women) attending 2-year and 4-year colleges in Hawaii. Results: Among participants who were never marijuana users at baseline, being a dual user of cigarette and e-cigarette at baseline was the strongest predictor of marijuana vaping initiation, followed by baseline cigarette-only and e-cigarette-only use. Higher prevalence of regular marijuana users in one's social networks, but not e-cigarette users or cigarette smokers, significantly predicted marijuana vaping initiation a year later. Among baseline current e-cigarette users and lifetime marijuana users, higher presence in social networks of individuals who frequented vape shops at baseline was a significant predictor of increased current marijuana vaping at one-year follow-up. Conclusions: Dual use of cigarette and e-cigarette and greater presence in social networks of marijuana users and people who frequent vape shops appear to be robust predictors of marijuana vaping onset and escalation among young adults. In addition to promoting e-cigarette use prevention/cessation, efforts to control marijuana vaping may need to consider promoting smoking prevention/cessation and the effects of increasing prevalence of marijuana use.