title: Childhood trauma and childhood urbanicity in relation to psychotic disorder.
abstract: BACKGROUND
  Urban upbringing and childhood trauma are both associated with psychotic disorders. However, the association between childhood urbanicity and childhood trauma in psychosis is poorly understood. The urban environment could occasion a background of social adversity against which any effect of childhood trauma increases. Also, any impact of the urban environment on likelihood of exposure to childhood trauma could be stronger in children who later develop psychotic disorder. The aim of this study was twofold: (1) to investigate whether childhood urbanicity moderates the effect of childhood trauma, in a model predicting psychotic disorder; (2) to investigate whether there is an association between the urban environment and childhood trauma and whether this is moderated by genetic liability for psychotic disorder.
  
  
  METHODS
  Patients with a diagnosis of non-affective psychotic disorder (n = 1119) and 589 healthy controls from the Netherlands and Belgium were studied. Childhood trauma was assessed with the Dutch version of the Childhood Trauma Questionnaire Short Form. Urban exposure was defined at four levels, considering the population density, using data from Statistics Netherlands and the equivalent database in Belgium.
  
  
  RESULTS
  There was a significant interaction between childhood urbanicity on the one hand and childhood trauma on the other, indicating that trauma was significantly associated with psychotic disorder, with increasing odds ratios for higher levels of childhood urbanicity. In addition, there was weak evidence that childhood urbanicity was associated with childhood trauma in the patient group: higher levels of childhood urbanicity were associated with higher trauma scores.
  
  
  CONCLUSIONS
  The urban environment may moderate the risk-increasing effect of childhood trauma for psychotic disorder and childhood urbanicity may be a risk factor for childhood trauma in individuals who later develop psychotic disorder.
authors.affiliation: Department of Psychiatry and Psychology, Maastricht University, PO Box 616 (DRT10), 6200 MD, Maastricht, The Netherlands.
authors.forename: Aleida
authors.initials: A
authors.lastname: Frissen
authors.affiliation: Department of Psychiatry and Psychology, Maastricht University, PO Box 616 (DRT10), 6200 MD, Maastricht, The Netherlands. R.Lieverse@maastrichtuniversity.nl.
authors.forename: Ritsaert
authors.initials: R
authors.lastname: Lieverse
authors.affiliation: Department of Psychiatry and Psychology, Maastricht University, PO Box 616 (DRT10), 6200 MD, Maastricht, The Netherlands.
authors.forename: Marjan
authors.initials: M
authors.lastname: Drukker
authors.affiliation: Department of Psychiatry and Psychology, Maastricht University, PO Box 616 (DRT10), 6200 MD, Maastricht, The Netherlands.
authors.forename: Ruud
authors.initials: R
authors.lastname: van Winkel
authors.affiliation: Department of Psychiatry and Psychology, Maastricht University, PO Box 616 (DRT10), 6200 MD, Maastricht, The Netherlands.
authors.forename: Philippe
authors.initials: P
authors.lastname: Delespaul
mesh_terms: D000328:Adult; D000069586:Adult Survivors of Child Adverse Events / Q000523:psychology* / Q000706:statistics & numerical data; D001530:Belgium / Q000453:epidemiology; D016022:Case-Control Studies; D016208:Databases, Factual; D005260:Female; D006801:Humans; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D011156:Population Density; D011618:Psychotic Disorders / Q000453:epidemiology* / Q000523:psychology*; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014505:Urban Population
keywords: Childhood; Environment; Psychosis; Trauma; Urbanicity