Data suggest that the ascendancy of medicalization, legalization, and social acceptability of marijuana has resulted in an overall rise of past-year marijuana use from 11.0% (25.8 million) in 2002 to 15.9% (43.5 million) in 2018 among the US population aged 12 or older. Paralleling these trends is mounting apprehension of the health consequences of marijuana, especially among adolescents. Evidence indicates that early versus later initiation of marijuana use is associated with higher rates of addiction, impaired cognition, pre-clinical or clinical symptoms of psychosis, schizophrenia, depression, suicidality, and reduced educational achievement or employment status. With peak marijuana use found to be among adults of child-bearing and -rearing ages, parental use conceivably poses a direct environmental risk of normalizing marijuana use and enabling easy access to marijuana for children living at home.

For a study published in JAMA Network Open, my colleagues (B. Han, W. Compton, C. Jones, E. Lopez, E. McCance-Katz) and I sought to determine whether intergenerational associations are detectable within specific substances, across substances, and across a broad age range of offspring (aged 12-30 years) living in the same household as a parent using marijuana. Most importantly, we simultaneously examined associations between parental marijuana use at detailed frequency levels and adolescent and young adult offspring substance use.

Parental Influence

We used repeated cross-sectional survey data on adolescents or young adults living with a parent (mother or father) from the nationally representative 2015-2018 National Surveys on Drug Use and Health.  More than 24,000 father-offspring or mother-offspring dyads were sampled. Parental marijuana use status was compared with offspring’s marijuana, alcohol, and tobacco use and opioid misuse.

We found substantial past-year marijuana use of 7.6% to 9.6% among mothers or fathers living with offspring. Parental past-year marijuana use was consistently associated with increased unadjusted prevalence of past-year marijuana, tobacco, and alcohol use and opioid misuse among both adolescent and young adult offspring (Table). Even among parents with lifetime, but no past-year marijuana use or relatively less frequent use (<52 days in the past year), unadjusted prevalence of past-year substance use among offspring was generally elevated.

Multivariable models adjusting for potential confounders related to offspring, familial, and environmental factors suggested that parental marijuana use was a specific risk factor for marijuana and tobacco use by both adolescent and young adult offspring, as well as for alcohol use by adolescent offspring.

Adolescent offspring’s substance use appeared to be particularly associated with mother’s marijuana use status. Our study indicates that a mother’s marijuana use status could have a pivotal role in the development of her adolescent offspring. Environmentally mediated normalization of substance use and increased access to substances at home are possible explanations. Regardless of mechanisms, providers and parents alike should be aware of the significant influence of parenting, parental marijuana use, and the poor prognosis of early marijuana initiators.

Protecting Children

Given the poor prognosis of substance use disorders for long-term outcomes, direct and indirect screening of family members and counseling for marijuana use in pediatric and general medical settings is an important and achievable goal. A positive screen should trigger counseling of parents on risks posed by using and storing marijuana, tobacco, or opioids at home, educating parents on risk and protective factors, and offering reassurances that substance use is modifiable.

Future research should focus on the feasibility of pediatrician and other primary care physicians performing screening for substance use of parents and offspring living in the same households, and whether screening alone or combined with counseling alters parental substance use.