title: Do early experiences with cannabis vary in cigarette smokers?
abstract: BACKGROUND
  We examine whether regular cigarette smokers were more likely to be exposed to and use cannabis at an earlier age, and further, upon initiation, whether their initial experiences with cannabis varied from those reported by never/non-regular cigarette smokers.
  
  
  METHODS
  A sample of 3797 Australian twins and siblings aged 21-46 years was used. Survival analyses examined whether cigarette smokers were at increased likelihood of early opportunity to use cannabis and early onset of cannabis use. Logistic regression examined whether cigarette smokers reported greater enjoyment of their cannabis experience, inhaling on the first try, differing positive and negative initial subjective reactions, smoked cigarettes with cannabis the first time and were more likely to try cannabis again within a week.
  
  
  RESULTS
  Regular cigarette smokers were more likely to report an earlier opportunity to use cannabis and early onset of cannabis use. Regular cigarette smokers were also considerably more likely to have enjoyed their first experience with cannabis and reported higher rates of positive initial reactions. They were more likely to report inhaling on the first try and smoking cigarettes with cannabis. Potentially negative subjective reactions were also elevated in regular cigarette smokers. Importantly, cigarette smokers were at 1.87 increased odds of smoking cannabis within a week of their initial use.
  
  
  CONCLUSIONS
  These findings indicate that the well-known overlap in cannabis and cigarette smoking behaviors may evolve as early as opportunity to use and extend through the course of the substance use trajectory.
authors.affiliation: Washington University School of Medicine, Department of Psychiatry, 660 S. Euclid, CB 8134, Saint 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: Nicholas G
authors.initials: NG
authors.lastname: Martin
authors.forename: Michael T
authors.initials: MT
authors.lastname: Lynskey
mesh_terms: D000328:Adult; D000367:Age Factors; D001315:Australia; D005260:Female; D006801:Humans; D008297:Male; D008385:Marijuana Smoking / Q000523:psychology*; D008875:Middle Aged; D016016:Proportional Hazards Models; D035781:Siblings; D012907:Smoking / Q000523:psychology*; D014427:Twins