title: Pre-morbid Conduct Disorder symptoms are associated with cannabis use among individuals with a first episode of psychosis.
abstract: BACKGROUND
  Early cannabis use has consistently been associated with an increased risk for the later development of psychosis. Studies suggest that Conduct Disorder (CD) is more common amongst young people who later go on to develop psychosis. CD has been associated with greater and earlier cannabis use in general population samples. Based on this evidence, we hypothesised that among patients experiencing their first episode of psychosis, the presence of CD symptoms prior to age 15 would be associated with cannabis use.
  
  
  METHODS
  102 patients experiencing a first episode of psychosis were interviewed to assess CD symptoms prior to age 15 and use of cannabis and other substances.
  
  
  RESULTS
  The number of CD symptoms was significantly associated with lifetime cannabis use (odds ratio=5.41 (1.76-16.57), p=0.03) and with first use of cannabis before age 14 (odds ratio=1.46 (1.12-1.92), p=0.006), after controlling for stimulant/hallucinogen use and level of education.
  
  
  CONCLUSIONS
  Among patients experiencing a first episode of psychosis, CD symptoms were significantly associated with use of cannabis and with use by age 14. Among individuals vulnerable for psychosis, CD symptoms may independently increase the likelihood of cannabis use which in turn increases the risk of psychosis.
authors.affiliation: King's College London, Department of Forensic and Neurodevelopmental Sciences (Box P023), NIHR Biomedical Research Centre, Institute of Psychiatry, King's Health Partners, De Crespigny Park, London SE5 8AF, United Kingdom. charlotte.malcolm@kcl.ac.uk
authors.forename: Charlotte P
authors.initials: CP
authors.lastname: Malcolm
authors.forename: Marco M
authors.initials: MM
authors.lastname: Picchioni
authors.forename: Marta
authors.initials: M
authors.lastname: DiForti
authors.forename: Gisela
authors.initials: G
authors.lastname: Sugranyes
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Cooke
authors.forename: Candice
authors.initials: C
authors.lastname: Joseph
authors.forename: Grant
authors.initials: G
authors.lastname: McQueen
authors.forename: Alessandra
authors.initials: A
authors.lastname: Paparelli
authors.forename: Simona
authors.initials: S
authors.lastname: Stilo
authors.forename: Jennifer
authors.initials: J
authors.lastname: O'Connor
authors.forename: Craig
authors.initials: C
authors.lastname: Morgan
authors.forename: Robin M
authors.initials: RM
authors.lastname: Murray
authors.forename: Sheilagh
authors.initials: S
authors.lastname: Hodgins
mesh_terms: D000328:Adult; D000367:Age Factors; D019955:Conduct Disorder / Q000150:complications* / Q000453:epidemiology* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000150:complications* / Q000453:epidemiology*; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000150:complications* / Q000453:epidemiology* / Q000523:psychology; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult