Associations of Parental Marijuana Use With Offspring Marijuana, Tobacco, and Alcohol Use and Opioid Misuse.

Importance: Marijuana use is increasing among adults and often co-occurs with other substance use; therefore, it is important to examine whether parental marijuana use is associated with elevated risk of substance use among offspring living in the same household. Objective: To examine associations of parental marijuana use with offspring marijuana, tobacco, and alcohol use and opioid misuse. Design, Setting, and Participants: This cross-sectional study used survey data from the 2015 through 2018 National Surveys on Drug Use and Health (NSDUH), which provide nationally representative data on adolescents or young adults living with a parent (the mother or the father). Annual average percentages were based on survey sampling weights. Final analyses were conducted September 21 through 23, 2019. Exposures: Parental marijuana use status. Main Outcomes and Measures: Offspring self-reported use of marijuana, tobacco, or alcohol or misuse of opioids. Results: Survey respondents included 24 900 father-offspring or mother-offspring dyads sampled from the same household. Among mothers living with adolescent offspring, 8.2% (95% CI, 7.3%-9.2%) had past-year marijuana use, while 7.6% (95% CI, 6.2%-9.2%) of mothers living with young adult offspring had past-year marijuana use. Among fathers living with adolescent offspring, 9.6% (95% CI, 8.5%-10.8%) had past-year marijuana use, and 9.0% (95% CI, 7.4%-10.9%) of fathers living with young adult offspring had past-year marijuana use. Compared with adolescents whose mothers never used marijuana, adjusted relative risk (ARR) of past-year marijuana use was higher among those whose mothers had lifetime (without past-year) marijuana use (ARR, 1.3; 95% CI, 1.1-1.6; P = .007), less than 52 days of past-year marijuana use (ARR, 1.7; 95% CI, 1.1-2.7; P = .02), or 52 days or more of past-year marijuana use (ARR, 1.5; 95% CI, 1.1-2.2; P = .02). Compared with young adults whose mothers never used marijuana, adjusted risk of past-year marijuana use was higher among those whose mothers had lifetime (without past-year) marijuana use (ARR, 1.4; 95% CI, 1.1-1.7; P = .001), less than 52 days of past-year marijuana use (ARR, 1.5; 95% CI, 1.0-2.3; P = .049), or 52 days or more of past-year marijuana use (ARR, 1.8; 95% CI, 1.3-2.5; P = .002). Compared with adolescents whose fathers never used marijuana, adolescents whose fathers had less than 52 days of past-year marijuana use were more likely to use marijuana (ARR, 1.8; 95% CI, 1.2-2.7; P = .006). Compared with young adults whose fathers never used marijuana, young adults whose fathers had 52 days or more of past-year marijuana use were more likely to use marijuana (ARR, 2.1; 95% CI, 1.6-2.9; P < .001). Compared with their peers whose parents never used marijuana and after adjusting for covariates, the adjusted risk of past-year tobacco use was higher among adolescents whose mothers had lifetime marijuana use (ARR, 1.3; 95% CI, 1.0-1.6; P = .03), less than 52 days of past-year marijuana use (ARR, 1.5; 95% CI, 1.0-2.1; P = .04), or 52 days or more of past-year marijuana use (ARR, 1.6; 95% CI, 1.1-2.3; P = .03); adolescents whose fathers had lifetime marijuana use (ARR, 1.5; 95% CI, 1.1-1.9; P = .004) or 52 days or more of past-year marijuana use (ARR, 1.8; 95% CI, 1.2-2.7; P = .006); young adults whose mothers had lifetime marijuana use (ARR, 1.2; 95% CI, 1.0-1.4; P = .04); and young adults whose fathers had 52 days or more of past-year marijuana use (ARR, 1.4; 95% CI, 1.0-1.9; P = .046). Compared with their peers whose parents had no past marijuana use and after adjusting for covariates, risk of past-year alcohol use was higher among adolescents whose mothers had lifetime marijuana use (ARR, 1.2; 95% CI, 1.1-1.4; P = .004), less than 52 days of past-year marijuana use (ARR, 1.5; 95% CI, 1.2-1.9; P = .002), or 52 days or more of past-year marijuana use (ARR, 1.3; 95% CI, 1.0-1.7; P = .04). After adjusting for covariates, parental marijuana use was not associated with opioid misuse by offspring. Conclusions and Relevance: In this cross-sectional study, parental marijuana use was associated with increased risk of substance use among adolescent and young adult offspring living in the same household. Screening household members for substance use and counseling parents on risks posed by current and past marijuana use are warranted.