title: The global epidemiology and contribution of cannabis use and dependence to the global burden of disease: results from the GBD 2010 study.
abstract: OBJECTIVE
  Estimate the prevalence of cannabis dependence and its contribution to the global burden of disease.
  
  
  METHODS
  Systematic reviews of epidemiological data on cannabis dependence (1990-2008) were conducted in line with PRISMA and meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines. Culling and data extraction followed protocols, with cross-checking and consistency checks. DisMod-MR, the latest version of generic disease modelling system, redesigned as a Bayesian meta-regression tool, imputed prevalence by age, year and sex for 187 countries and 21 regions. The disability weight associated with cannabis dependence was estimated through population surveys and multiplied by prevalence data to calculate the years of life lived with disability (YLDs) and disability-adjusted life years (DALYs). YLDs and DALYs attributed to regular cannabis use as a risk factor for schizophrenia were also estimated.
  
  
  RESULTS
  There were an estimated 13.1 million cannabis dependent people globally in 2010 (point prevalence0.19% (95% uncertainty: 0.17-0.21%)). Prevalence peaked between 20-24 yrs, was higher in males (0.23% (0.2-0.27%)) than females (0.14% (0.12-0.16%)) and in high income regions. Cannabis dependence accounted for 2 million DALYs globally (0.08%; 0.05-0.12%) in 2010; a 22% increase in crude DALYs since 1990 largely due to population growth. Countries with statistically higher age-standardised DALY rates included the United States, Canada, Australia, New Zealand and Western European countries such as the United Kingdom; those with lower DALY rates were from Sub-Saharan Africa-West and Latin America. Regular cannabis use as a risk factor for schizophrenia accounted for an estimated 7,000 DALYs globally.
  
  
  CONCLUSIONS
  Cannabis dependence is a disorder primarily experienced by young adults, especially in higher income countries. It has not been shown to increase mortality as opioid and other forms of illicit drug dependence do. Our estimates suggest that cannabis use as a risk factor for schizophrenia is not a major contributor to population-level disease burden.
authors.affiliation: National Drug and Alcohol Research Centre, University of New South Wales, Sydney, New South Wales, Australia ; Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Louisa
authors.initials: L
authors.lastname: Degenhardt
authors.forename: Alize J
authors.initials: AJ
authors.lastname: Ferrari
authors.forename: Bianca
authors.initials: B
authors.lastname: Calabria
authors.forename: Wayne D
authors.initials: WD
authors.lastname: Hall
authors.forename: Rosana E
authors.initials: RE
authors.lastname: Norman
authors.forename: John
authors.initials: J
authors.lastname: McGrath
authors.forename: Abraham D
authors.initials: AD
authors.lastname: Flaxman
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Engell
authors.forename: Greg D
authors.initials: GD
authors.lastname: Freedman
authors.forename: Harvey A
authors.initials: HA
authors.lastname: Whiteford
authors.forename: Theo
authors.initials: T
authors.lastname: Vos
mesh_terms: D000367:Age Factors; D002188:Cannabis / Q000009:adverse effects*; D015897:Comorbidity; D006233:Persons with Disabilities / Q000706:statistics & numerical data; D005260:Female; D062306:Geography, Medical; D014943:Global Health / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000453:epidemiology*; D015995:Prevalence; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology / Q000209:etiology; D012737:Sex Factors