title: Cannabis use disorder and age at onset of psychosis--a study in first-episode patients.
abstract: BACKGROUND
  Age at onset of psychosis (AAO) may be younger in patients with cannabis use disorders (CUD) compared to those without CUD (NCUD). Previous studies included CUD co-morbid with other substance use disorders (SUD), and many did not control for confounders.
  
  
  METHODS
  Controlling for relevant confounders, differences in AAO between patients with and without CUD excluding those with any other SUD were analyzed in a large representative file audit of 625 first-episode psychosis (FEP) patients (age 14 to 29years) admitted to the Early Psychosis Prevention and Intervention Centre in Melbourne, Australia.
  
  
  RESULTS
  Three quarters of the 625 FEP patients had a CUD. Cannabis use started before psychosis onset in 87.6% of patients. AAO was not significantly different between CUD (without other SUD, n=201) and NCUD (n=157). However, AAO was younger in those with early CUD (starting age 14 or younger) compared to NCUD (F(1)=5.2; p=0.024; partial η(2)=0.026). Earlier age at onset of cannabis use predicted earlier age at onset of psychosis (β=-0.49, R(2)-change=0.25, p<0.001).
  
  
  CONCLUSIONS
  Only CUD starting age 14 or younger was associated with an earlier AAO at a small effect size. These findings suggest that CUD may exert an indirect effect on brain maturation resulting in earlier AAO potentially only in cannabis sensitive subjects.
authors.affiliation: University Hospital of Child and Adolescent Psychiatry, Bern, Switzerland. bschimme@aol.com
authors.forename: Benno G
authors.initials: BG
authors.lastname: Schimmelmann
authors.forename: Philippe
authors.initials: P
authors.lastname: Conus
authors.forename: Sue M
authors.initials: SM
authors.lastname: Cotton
authors.forename: Stephan
authors.initials: S
authors.lastname: Kupferschmid
authors.forename: Anne
authors.initials: A
authors.lastname: Karow
authors.forename: Frauke
authors.initials: F
authors.lastname: Schultze-Lutter
authors.forename: Patrick D
authors.initials: PD
authors.lastname: McGorry
authors.forename: Martin
authors.initials: M
authors.lastname: Lambert
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D001315:Australia / Q000453:epidemiology; D002186:Cannabinoids; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000453:epidemiology*; D011618:Psychotic Disorders / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult
chemical_list: D002186:Cannabinoids