title: Cigarette smoking may modify the association between cannabis use and adiposity in males.
abstract: BACKGROUND
  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 12-13years at cohort inception provided data on past-year cannabis use and number of cigarettes smoked per day in the past three months, at age 20years. Outcomes included change in body mass index (BMI) and in waist circumference (WC) from ages 17 to 24years. 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.
  
  
  CONCLUSIONS
  Smoking cigarettes appears to modify the association between cannabis use and adiposity in young men.
authors.affiliation: Department of Social and Preventive Medicine, University of Montreal, 7101 ave du Parc, Montreal, Quebec H3N 1X7, Canada. Electronic address: emily.dube@umontreal.ca.
authors.forename: Emily
authors.initials: E
authors.lastname: Dubé
authors.affiliation: Department of Social and Preventive Medicine, University of Montreal, 7101 ave du Parc, Montreal, Quebec H3N 1X7, Canada; Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 850 Saint-Denis, Montreal, Quebec H2X 0A9, Canada; Institut National de Santé Publique du Québec, 190 Crémazie E, Montreal, Quebec H2P 1E2, Canada. Electronic address: jennifer.oloughlin@umontreal.ca.
authors.forename: Jennifer
authors.initials: J
authors.lastname: O'Loughlin
authors.affiliation: Department of Social and Preventive Medicine, University of Montreal, 7101 ave du Parc, Montreal, Quebec H3N 1X7, Canada; Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 850 Saint-Denis, Montreal, Quebec H2X 0A9, Canada; Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, University of Western Ontario, 1151 Richmond St., London, Ontario N6A 5C1, Canada. Electronic address: igor.karp.1@umontreal.ca.
authors.forename: Igor
authors.initials: I
authors.lastname: Karp
authors.affiliation: Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 850 Saint-Denis, Montreal, Quebec H2X 0A9, Canada; Department of Psychiatry, Université de Montréal, 2900, Édouard-Montpetit, Montreal, Quebec H3C 3J7, Canada. Electronic address: didier.jutras-aswad@umontreal.ca.
authors.forename: Didier
authors.initials: D
authors.lastname: Jutras-Aswad
mesh_terms: D050154:Adiposity / Q000187:drug effects*; D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008385:Marijuana Smoking / Q000009:adverse effects*; D008603:Mental Health; D011446:Prospective Studies; D011792:Quebec; D012727:Sex Characteristics; D012907:Smoking / Q000009:adverse effects*; D012959:Socioeconomic Factors; D055105:Waist Circumference / Q000187:drug effects; D055815:Young Adult
keywords: Adiposity; Body mass index; Cannabis; Cigarette smoking; Longitudinal; Youth