title: [Can cannabis use increase the risk for schizophrenic psychoses?].
abstract: BACKGROUND
  In recent years, cannabis has been increasingly discussed as one of the most important environmental risk factors for developing schizophrenic psychoses. This is mainly due to the following observations. (i) Cannabis at high doses can cause acute transient psychotic symptoms even in healthy individuals. (ii) Patients with schizophrenia abuse cannabis more often than age-matched healthy controls.
  
  
  OBJECTIVE
  It is still controversial whether cannabis use can cause schizophrenic psychoses that would not have occurred otherwise. In our review, we have critically evaluated the evidence for a causal link between cannabis use and schizophrenic psychoses.
  
  
  METHODS
  A systematic literature review in PubMed, ISI Web of Science and PsycINFO was carried out using the following keywords: cannabis, marijuana, THC, hashish, psychosis, schizophrenia.
  
  
  CONCLUSIONS
  We have concluded that although a causal relationship between cannabis use and schizophrenic psychoses cannot be definitely proven, the available evidence strongly supports its plausibility. Furthermore, the results of the review indicate that cannabis might cause psychosis especially in individuals with a predisposition for schizophrenia and in adolescents with an early onset of cannabis use.
authors.affiliation: Zentrum für Gender Research und Früherkennung, Universitäre Psychiatrische Kliniken, Universitätsspital Basel, Schweiz.
authors.forename: H
authors.initials: H
authors.lastname: Bugra
authors.forename: C
authors.initials: C
authors.lastname: Rapp
authors.forename: E
authors.initials: E
authors.lastname: Studerus
authors.forename: J
authors.initials: J
authors.lastname: Aston
authors.forename: S
authors.initials: S
authors.lastname: Borgwardt
authors.forename: A
authors.initials: A
authors.lastname: Riecher-Rössler
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D003072:Cognition Disorders / Q000139:chemically induced / Q000523:psychology; D020022:Genetic Predisposition to Disease; D006801:Humans; D008385:Marijuana Smoking / Q000009:adverse effects* / Q000453:epidemiology / Q000523:psychology*; D008875:Middle Aged; D009042:Motivation / Q000502:physiology; D011605:Psychoses, Substance-Induced / Q000523:psychology; D012306:Risk; D012559:Schizophrenia / Q000453:epidemiology / Q000209:etiology*; D012565:Schizophrenic Psychology; D055815:Young Adult