A B S T R A C TBackground: With an increase in marijuana use among adults in the United States (US), understanding the potential impact of marijuana use on tobacco use and associated behavioral and health consequences, including respiratory conditions, is necessary. Method: Survey responses from Wave 1 of the nationally representative Population Assessment of Tobacco and Health (PATH) Study were used to assess tobacco use and marijuana use among non-current tobacco users (n = 17,952) and current established tobacco-users classified as: cigarette only users (n = 8689), e-cigarette only users (n = 437), cigar only (traditional, cigarillo, or filtered) users (n = 706), hookah only users (n = 461), smokeless tobacco only users (n = 971), cigarette + e-cigarette users (n = 709), and users of multiple tobacco products (n = 2314). Results: When compared to non-current tobacco users, each tobacco user group except smokeless only users had higher odds (odds ratios ranging from 3.86-8.07) of reporting current marijuana use. Among current tobacco users, higher levels of tobacco dependence did not explain the relationship between tobacco use and marijuana use. Additionally, concurrent marijuana use was associated with lower odds of attempts to quit tobacco (OR = 0.86, 95% CI = 0.79, 0.94, p < 0.001) and a higher probability (OR = 1.35, 95CI = 1.21, 1.51, p < 0.01) of reporting a history of respiratory disease. Conclusions:The association between concurrent use of tobacco and marijuana and higher tobacco dependence and lower rates of quit attempts suggests the potential for sustained tobacco use and deleterious health effects. Further, marijuana use may represent an additive risk for respiratory harm among concurrent users of tobacco and marijuana.

Recent studies suggest that e-cigarette use among youth may be associated with increased risk of cigarette initiation. The goal of this study was to test the hypothesis that use of e-cigarettes among young adult non-daily cigarette smokers would be associated with increased cigarette consumption. Participants (n = 391; 52% male) were 18-24 year-old non-daily cigarette smokers recruited from across California. Cigarette and e-cigarette use were assessed online or via mobile phone every three months for one year between March 2015 and December 2016. Longitudinal negative binomial regression models showed that, adjusted for propensity for baseline e-cigarette use, non-daily smokers who reported more frequent use of e-cigarettes upon study entry reported greater quantity and frequency of cigarette smoking at baseline and greater increases in cigarette quantity over 12 months than non-daily cigarette only smokers (ps < .01). During the 12 months of assessment, more consistent consumption of e-cigarettes was associated with greater quantity and frequency of cigarette use (ps < .01); these effects did not vary over time. Findings suggest that among non-daily smokers, young adults who use e-cigarettes tend to smoke more cigarettes and to do so more frequently. Such individuals may be at greater risk for chronic tobacco use and dependence.

Introduction Understanding predictors of e-cigarette and hookah use among young adults is important in light of their increasing prevalence, particularly in younger populations. The purpose of this study was to test the hypothesis that young adult non-daily cigarette smokers’ use of e-cigarettes and hookah would be positively associated with their expectancies about these products. Methods Young adults (n = 377, 58.0% male) aged 18–24 years (M = 20.5, SD = 1.8) who had been non-daily smokers for at least six months but had never been daily smokers completed a baseline assessment online or via mobile phone as part of a larger, longitudinal study. Results Approximately one in three participants reported any e-cigarette (34.0%) and/or hookah (33.4%) use in the past 14 days; 37% of those who used either product reported using both. More positive e-cigarette expectancies were associated with higher odds of any e-cigarette use and with heavier use in the past two weeks. Similarly, more positive expectancies for hookah use predicted greater odds of any use as well as more frequent use of hookah (all ps < .001). Cigarette expectancies were correlated with ANTP expectancies, but did not account for the latter’s association with ANTP use. Conclusions Findings suggest that expectancies play a role in determining whether young adult cigarette smokers also use these nicotine products. These data also suggest use of e-cigarettes and/or hookah may be as common as not among young adult nondaily smokers.

E-cigarettes have been suggested as a strategy for reducing harm from cigarettes. While e-cigarettes could be a less-harmful alternative to cigarettes for those trying to quit, there may also be costs that outweigh any benefits of reduction. The purpose of the present study was to prospectively investigate perceptions of e-cigarettes, cigarette smoking intentions and their associations with e-cigarette use over time. Community participants (n = 348, 57% male) aged 18–24 were recruited for a longitudinal study of tobacco use. Inclusion criteria included non-daily cigarette smoking for ≥ 6 months with no history of daily smoking. Participants reported e-cigarette use over the past 14 days at baseline and for the past 9 days at 3, 6, and 9 months. Assessments were completed online or via mobile phone. Across the 4 assessments, 22–33% of participants reported recent e-cigarette use. Intent to quit smoking cigarettes and intent to maintain smoking were unrelated to e-cigarette frequency. E-cigarette frequency was positively associated with perceiving e-cigarettes as less harmful than cigarettes and more positive e-cigarette expectancies (ps < .05). E-cigarette use was also more frequent among those who smoked cigarettes frequently and who used e-cigarettes to circumvent cigarette bans more often (ps < .05). The combination of these findings suggests that, at least among non-daily smoking young adults, other factors may influence frequency of e-cigarette use more than harm reduction. Findings instead seem consistent with the hypothesis that e-cigarettes are more often used to complement ongoing cigarette smoking.