Cigarette smoking may modify the association between cannabis use and adiposity in males

Introduction: The few population-based studies that investigate the association between cannabis use and adiposity are inconclusive possibly because nicotine moderates the effect of cannabis on adiposity. The objective was to test the hypotheses that the association between cannabis use and adiposity in young men and women is modified by cigarette smoking. Methods: Data were drawn from the Nicotine Dependence in Teens (NDIT) study, a 13-year prospective cohort investigation of the natural course of nicotine dependence. A total of 271 males and 319 females aged 1213 years at cohort inception provided data on past-year cannabis use and number of cigarettes smoked per day in the past three months, at age 20 years. Outcomes included change in body mass index (BMI) and in waist circumference (WC) from ages 17 to 24 years. The hypothesis was tested in multiple linear regression models that included interaction terms for cannabis use and cigarette smoking and controlled for physical activity, sedentary behavior, alcohol use, and level of the outcome at baseline. Results: The association between cannabis use and change in adiposity was U-shaped in male non-smokers and in females, and an inverted U-shape in male smokers. In males, the interaction between cannabis use and cigarette smoking was significant in both the models for change in BMI (p = 0.004; n = 271) and change in WC (p = 0.04; n = 250). In females, the interaction between cannabis use and cigarette smoking was not significant. Conclusion: Smoking cigarettes appears to modify the association between cannabis use and adiposity in young men. (C) 2015 Elsevier Inc. All rights reserved.