title: Childhood bullying and the association with psychosis in non-clinical and clinical samples: a review and meta-analysis.
abstract: BACKGROUND
  Approximately 11% of schoolchildren are bullied on a regular basis. It has been argued that continuous exposure to stress is related to the development of psychotic symptoms. The current study sought to investigate whether being bullied in childhood is related to the development of psychotic symptoms.
  
  
  METHODS
  A search of PubMed, PsycINFO and EMBASE was conducted. The reference lists of included papers were searched to identify other eligible papers. A meta-analysis was performed on a subgroup of studies.
  
  
  RESULTS
  We found four clinical and 10 general population studies that met inclusion criteria. The results of the clinical studies were mixed. However, the results of the non-clinical studies provided more consistent evidence that school bullying is related to the development of non-clinical psychotic symptoms. Stronger associations were found with increased frequency and severity and longer duration of being bullied. We performed a meta-analysis on seven population-based studies, yielding unadjusted and adjusted odds ratios (ORs) of 2.7 [95% confidence interval (CI) 2.1-3.6] and 2.3 (95% CI 1.5-3.4) respectively.
  
  
  CONCLUSIONS
  Although there is some evidence of an association between bullying and psychosis in clinical samples, the research is too sparse to draw any firm conclusions. However, population-based non-clinical studies support the role of bullying in the development of psychotic symptoms later in life. These findings are consistent with findings of an increased risk of psychotic symptoms among those exposed to other types of abuse.
authors.affiliation: Department of Psychiatry, Early Psychosis Section, Academic Medical Centre, University of Amsterdam, The Netherlands. d.s.vandam@amc.uva.nl
authors.forename: D S
authors.initials: DS
authors.lastname: van Dam
authors.forename: E
authors.initials: E
authors.lastname: van der Ven
authors.forename: E
authors.initials: E
authors.lastname: Velthorst
authors.forename: J P
authors.initials: JP
authors.lastname: Selten
authors.forename: C
authors.initials: C
authors.lastname: Morgan
authors.forename: L
authors.initials: L
authors.lastname: de Haan
mesh_terms: D000293:Adolescent; D000328:Adult; D058445:Bullying / Q000523:psychology*; D002648:Child; D019548:Crime Victims / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D010553:Personality Development; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology*; D012307:Risk Factors; D013223:Statistics as Topic; D055815:Young Adult