Reverse gateways? Frequent cannabis use as a predictor of tobacco initiation and nicotine dependence

Authors

  • George C. Patton,

    Corresponding author
    1. Centre for Adolescent Health
      George C. Patton, Centre for Adolescent Health, Royal Children's Hospital, Murdoch Children's Research Institute and  Department of Paediatrics, University of Melbourne, 2 Gatehouse Street, Parkville 3052, Victoria, Australia, Tel: 613 93456598, Fax: 613 93456502, E-mail: george.patton@rch.org.au
    Search for more papers by this author
  • Carolyn Coffey,

    1. Centre for Adolescent Health
    Search for more papers by this author
  • John B. Carlin,

    1. Clinical Epidemiology and Biostatistics Unit, Royal Children's Hospital, Murdoch Children's Research Institute and Department of Paediatrics, University of Melbourne, Australia
    Search for more papers by this author
  • Susan M. Sawyer,

    1. Centre for Adolescent Health
    Search for more papers by this author
  • Michael Lynskey

    1. Department of Psychiatry, Washington University School of Medicine, St Louis, USA
    Search for more papers by this author

George C. Patton, Centre for Adolescent Health, Royal Children's Hospital, Murdoch Children's Research Institute and  Department of Paediatrics, University of Melbourne, 2 Gatehouse Street, Parkville 3052, Victoria, Australia, Tel: 613 93456598, Fax: 613 93456502, E-mail: george.patton@rch.org.au

ABSTRACT

Aims  To examine the risk posed by cannabis use in young people for tobacco use disorders. Specifically we examined whether cannabis use in non-smokers predicted later initiation of tobacco use and whether cannabis use predicted later nicotine dependence in tobacco users.

Design  A 10-year eight-wave cohort study.

Setting  State of Victoria, Australia.

Participants  A community sample of 1943 participants initially aged 14–15 years.

Measurements  Self-report of tobacco and cannabis use was assessed in the teens using a computerized interview assessment and in young adulthood with a CATI assessment. The Fagerström Test for Nicotine Dependence was used to define nicotine dependence.

Findings  For teen non-smokers, at least one report of weekly cannabis use in the teens predicted a more than eightfold increase in the odds of later initiation of tobacco use (OR 8.3; 95% CI 1.9–36). For 21-year-old smokers, not yet nicotine-dependent, daily cannabis use raised the odds of nicotine dependence at the  age  of  24 years  more  than  threefold  (OR  3.6,  1.2,  10)  after  controlling  for possible confounders, including level of tobacco use and subsyndromal signs of nicotine dependence.

Conclusions  Weekly or more cannabis use during the teens and young adulthood is associated with an increased risk of late initiation of tobacco use and progression to nicotine dependence. If this effect is causal, it may be that a heightened risk of nicotine dependence is the most important health consequence of early frequent cannabis use.

Ancillary