title: Factors associated with the timing and onset of cannabis use and cannabis use disorder: results from the 2007 Australian National Survey of Mental Health and Well-Being.
abstract: OBJECTIVE
  To investigate the predictors of both initiation of cannabis use and transition to cannabis use disorder (CUD) in a nationally representative sample using discrete-time survival analyses.
  
  
  METHODS
  Data from a nationally representative sample of 6935 Australian adults. Retrospective data on age of first cannabis use and onset of CUD were used to construct pseudo-longitudinal datasets and survival models used to evaluate factors associated with age of first use and time from first use to onset of CUD.
  
  
  RESULTS
  The oldest cohort (born 1942-1951) had lower cannabis use than younger cohorts, with first use also occurring at an older age. Multivariable discrete-time survival models showed other substance use, tobacco and alcohol use at very young ages, and mental disorders were associated with increased risk of cannabis use. There were 7.5% of those <65 years old at interview who had a lifetime CUD; mean time from first use to the onset of CUD was 3.3 years, with 90% of cases within eight years. Younger age of initiation and other substance use were strong predictors of the transition from use to CUD. Women with depression were more likely to develop a CUD; social phobia and panic disorder were also associated with transition from cannabis use to CUD.
  
  
  CONCLUSIONS
  Patterns of cannabis use differ across birth cohorts. There are multiple factors associated with use and transition to CUD, with other substance use a strong predictor. Mental disorders also predict initiation and progression to CUD.
authors.affiliation: Centre for Research on Ageing, Health and Wellbeing, The Australian National University, Canberra, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Butterworth
authors.forename: Tim
authors.initials: T
authors.lastname: Slade
authors.forename: Louisa
authors.initials: L
authors.lastname: Degenhardt
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia / Q000453:epidemiology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D002189:Marijuana Abuse / Q000453:epidemiology*; D008385:Marijuana Smoking / Q000453:epidemiology*; D001523:Mental Disorders / Q000453:epidemiology*; D008875:Middle Aged; D015999:Multivariate Analysis; D016584:Panic Disorder / Q000453:epidemiology; D010698:Phobic Disorders / Q000453:epidemiology; D012189:Retrospective Studies; D019966:Substance-Related Disorders / Q000453:epidemiology*; D016019:Survival Analysis; D055815:Young Adult
keywords: Australia; cannabis; epidemiology