title: Cannabis use and age at onset of psychosis: further evidence of interaction with COMT Val158Met polymorphism.
abstract: OBJECTIVE
  To examine, in a sample of young psychiatric patients, (n = 157, mean age 17.01 years (SD = 3.6)) whether i) age at first cannabis use and age at emergence of psychiatric disorders are related and ii) such a relationship is modulated by the Val158Met polymorphism in the COMT gene.
  
  
  METHODS
  Cannabis use profiles and COMT Val158Met genotypes were obtained from 80 inpatients with schizophrenia-spectrum disorders and 77 inpatients with other non-psychotic disorders.
  
  
  RESULTS
  First, age at first cannabis use correlates with age at onset in both schizophrenia-spectrum and other psychiatric disorder groups: those who started using cannabis earlier had an earlier age at onset of psychiatric disorders. Second, the distribution of the Val158Met genotypes was not different either between diagnosis groups or between cannabis users and non-users. Third, an interaction between Val158Met genotypes and cannabis use was observed specifically on age at emergence of psychotic disorders, with Val/Val genotype carriers showing an earlier age at onset than Met carriers.
  
  
  CONCLUSIONS
  Our results suggest the importance of brain maturation timing in which exposure to cannabis occurs. The COMT Val158Met genotype seems to modulate the association between cannabis and age at onset of psychotic disorders. These results are consistent with previous studies.
authors.affiliation: Anthropology Unit, Department of Animal Biology, Faculty of Biology, University of Barcelona, Spain.
authors.forename: G
authors.initials: G
authors.lastname: Estrada
authors.forename: M
authors.initials: M
authors.lastname: Fatjó-Vilas
authors.forename: M J
authors.initials: MJ
authors.lastname: Muñoz
authors.forename: G
authors.initials: G
authors.lastname: Pulido
authors.forename: M J
authors.initials: MJ
authors.lastname: Miñano
authors.forename: E
authors.initials: E
authors.lastname: Toledo
authors.forename: J M
authors.initials: JM
authors.lastname: Illa
authors.forename: M
authors.initials: M
authors.lastname: Martín
authors.forename: M L
authors.initials: ML
authors.lastname: Miralles
authors.forename: S
authors.initials: S
authors.lastname: Miret
authors.forename: S
authors.initials: S
authors.lastname: Campanera
authors.forename: C
authors.initials: C
authors.lastname: Bernabeu
authors.forename: M E
authors.initials: ME
authors.lastname: Navarro
authors.forename: L
authors.initials: L
authors.lastname: Fañanás
mesh_terms: D000293:Adolescent; D017668:Age of Onset; D002394:Catechol O-Methyltransferase / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000235:genetics; D008385:Marijuana Smoking; D008715:Methionine; D011110:Polymorphism, Genetic / Q000235:genetics*; D011618:Psychotic Disorders / Q000235:genetics*; D012559:Schizophrenia / Q000235:genetics; D014633:Valine
chemical_list: D008715:Methionine; D002394:Catechol O-Methyltransferase; D014633:Valine