title: Replication in two independent population-based samples that childhood maltreatment and cannabis use synergistically impact on psychosis risk.
abstract: BACKGROUND
  There may be biological plausibility to the notion that cannabis use and childhood trauma or maltreatment synergistically increase the risk for later development of psychotic symptoms. To replicate and further investigate this issue, prospective data from two independent population-based studies, the Greek National Perinatal Study (n=1636) and The Netherlands Mental Health Survey and Incidence Study (NEMESIS) (n=4842), were analyzed.
  
  
  METHODS
  Two different data sets on cannabis use and childhood maltreatment were used. In a large Greek population-based cohort study, data on cannabis use at age 19 years and childhood maltreatment at 7 years were assessed. In addition, psychotic symptoms were assessed using the Community Assessment of Psychic Experiences (CAPE). In NEMESIS, the Composite International Diagnostic Interview (CIDI) was used to assess psychotic symptoms at three different time points along with childhood maltreatment and lifetime cannabis use.
  
  
  RESULTS
  A significant adjusted interaction between childhood maltreatment and later cannabis use was evident in both samples, indicating that the psychosis-inducing effects of cannabis were stronger in individuals exposed to earlier sexual or physical mistreatment [Greek National Perinatal Study: test for interaction F(2, 1627)=4.18, p=0.02; NEMESIS: test for interaction χ2(3)=8.08, p=0.04].
  
  
  CONCLUSIONS
  Cross-sensitivity between childhood maltreatment and cannabis use may exist in pathways that shape the risk for expression of positive psychotic symptoms.
authors.affiliation: Department of Psychiatry and Neuropsychology, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht University Medical Centre, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Konings
authors.forename: N
authors.initials: N
authors.lastname: Stefanis
authors.forename: R
authors.initials: R
authors.lastname: Kuepper
authors.forename: R
authors.initials: R
authors.lastname: de Graaf
authors.forename: M
authors.initials: M
authors.lastname: ten Have
authors.forename: J
authors.initials: J
authors.lastname: van Os
authors.forename: C
authors.initials: C
authors.lastname: Bakoula
authors.forename: C
authors.initials: C
authors.lastname: Henquet
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D002648:Child; D002649:Child Abuse / Q000523:psychology / Q000706:statistics & numerical data*; D004305:Dose-Response Relationship, Drug; D004812:Epidemiologic Methods; D005260:Female; D006115:Greece / Q000453:epidemiology; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000453:epidemiology* / Q000523:psychology; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011618:Psychotic Disorders / Q000453:epidemiology* / Q000523:psychology; D051381:Rats; D013315:Stress, Psychological / Q000453:epidemiology / Q000523:psychology; D011795:Surveys and Questionnaires; D055815:Young Adult