Electronic cigarette use in adolescence is associated with later cannabis use

Background: Research is needed to determine whether e-cigarette use during adolescence is associated with higher odds of subsequent cannabis use, net of tobacco cigarette use and childhood confounders. Methods: Multivariable logistic regressions predicting using cannabis by age 17 based upon prospective, intergenerational data from 10,251 youth in a nationally representative UK birth cohort followed from infancy who had not used cannabis by age 14. The focal predictor is e-cigarette use by age 14 in the context of the potential confounder tobacco cigarette use. Regressions include sociodemographic background and risk factors assessed at age 11 (e.g., alcohol initiation, problem behaviors, parental and peer smoking) and during early childhood (e.g., maternal smoking during pregnancy, parental substance use). Results: Youth use of e-cigarettes by age 14 was associated with 2.8 times higher odds of subsequent cannabis use by age 17 [OR 2.75; 95% CI 1.82,4.15], net of tobacco cigarette smoking and childhood confounders. Similarly, use of e-cigarettes by age 14 was associated with 2.5 times higher odds [OR 2.46; 95% CI 1.48,4.08] of frequent cannabis use at age 17 (>10 times in prior year). If youth used both e-cigarettes and tobacco cigarettes by age 14, the probabilities of cannabis initiation were 75% and of frequent use was 25% by age 17, compared to probabilities of 23% and 6%, respectively, among youth who had used neither product. Conclusions: Findings add to accumulating evidence that adolescent e-cigarette use is associated with higher odds of later cannabis initiation and frequent use, independent of tobacco cigarette use.