title: Transitions to regular smoking and to nicotine dependence in women using cannabis.
abstract: BACKGROUND
  While there is substantial support in the literature for an increased prevalence of cannabis use in cigarette smokers, emerging studies allude to the possibility that cannabis users may, in turn, be at significantly elevated risk for rapid transitions in their cigarette smoking trajectories. If there is evidence in its favor, the increased rates of cigarette smoking in cannabis users may prove to be the most significant public health problem associated with cannabis use.
  
  
  METHODS
  In a sample of 3787 female twins (age range 18-29 years), we examined, using discrete-time survival analyses, whether women who reported cannabis use were at increased risk for regular cigarette smoking and progression to nicotine dependence.
  
  
  RESULTS
  After controlling for a large number of potential covariates, we found that women who used cannabis were at 4.4 and 2.8 increased hazards for transitioning from initiation to regular smoking and from regular smoking to nicotine dependence, respectively.
  
  
  CONCLUSIONS
  Cannabis use is associated with transitions to more involved stages of cigarette smoking in women. This is a source of public health concern, first due to the high mortality associated with cigarette smoking and second, due to the high prevalence of cannabis use in the general population.
authors.affiliation: Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA. arpana@wustl.edu
authors.forename: Arpana
authors.initials: A
authors.lastname: Agrawal
authors.forename: Pamela A F
authors.initials: PA
authors.lastname: Madden
authors.forename: Kathleen K
authors.initials: KK
authors.lastname: Bucholz
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Heath
authors.forename: Michael T
authors.initials: MT
authors.lastname: Lynskey
mesh_terms: D000293:Adolescent; D015984:Causality; D015331:Cohort Studies; D015897:Comorbidity; D003430:Cross-Sectional Studies; D004200:Diseases in Twins / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015993:Life Tables; D008137:Longitudinal Studies; D002189:Marijuana Abuse / Q000453:epidemiology*; D001523:Mental Disorders / Q000453:epidemiology; D008923:Missouri; D016016:Proportional Hazards Models; D012306:Risk; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology*; D014029:Tobacco Use Disorder / Q000453:epidemiology*