Medical Marijuana Legalization and Co-use in Adult Cigarette Smokers.

OBJECTIVES: We examined effects of long-term medical marijuana legalization on cigarette co-use in a sample of adults.

METHODS: We conducted secondary analysis using data from the 2014 US Tobacco Attitudes and Beliefs Survey, which consisted of cigarette smokers, aged ≥ 45 years (N = 506). Participants were categorized by their state residence, where medical marijuana was (1) illegal, (2) legalized < 10 years, and (3) legalized ≥ 10 years. The Web-based survey assessed participants' marijuana use, beliefs and attitudes on marijuana, and nicotine dependence using Fagerstrom Tolerance for Nicotine Dependence (FTND) and Hooked on Nicotine Checklist (HONC) scores.

RESULTS: In cigarette smokers aged ≥ 45 years, long-term legalization of medical marijuana was associated with stable positive increases in marijuana use prevalence (ever in a lifetime) (p = .005) and frequency (number of days in past 30 days) (unadjusted p = .005; adjusted p = .08). Those who reported marijuana co-use had greater FTND and HONC scores after adjusting for covariates (p = .05).

CONCLUSIONS: These preliminary findings warrant further examination of the potential impact of long-term legalization of medical marijuana on greater cigarette and marijuana co-use in adults and higher nicotine dependence among co-users at the population level.