title: Theory of mind in schizophrenia: meta-analysis.
abstract: BACKGROUND
  Mentalising impairment (an impaired ability to think about people in terms of their mental states) has frequently been associated with schizophrenia.
  
  
  OBJECTIVE
  To assess the magnitude of the deficit and analyse associated factors.
  
  
  METHODS
  Twenty-nine studies of mentalising in schizophrenia (combined n=1518), published between January 1993 and May 2006, were included to estimate overall effect size. Study descriptors predicted to influence effect size were analysed using weighted regression-analysis techniques. Separate analyses were performed for symptom subgroups and task types.
  
  
  RESULTS
  The estimated overall effect size was large and statistically significant (d=-1.255, P<0.0001) and was not significantly affected by sample characteristics. All symptom subgroups showed significant mentalising impairment, but participants with symptoms of disorganisation were significantly more impaired than the other subgroups (P<0.01).
  
  
  CONCLUSIONS
  This meta-analysis showed significant and stable mentalising impairment in schizophrenia. The finding that patients in remission are also impaired favours the notion that mentalising impairment represents a possible trait marker of schizophrenia.
authors.affiliation: Department of Child and Adolescent Psychiatry, University Medical Centre, Heidelberglaan 100, HPA01.468, 3508 GA Utrecht, The Netherlands. m.sprong-2@umcutrecht.nl
authors.forename: Mirjam
authors.initials: M
authors.lastname: Sprong
authors.forename: Patricia
authors.initials: P
authors.lastname: Schothorst
authors.forename: Ellen
authors.initials: E
authors.lastname: Vos
authors.forename: Joop
authors.initials: J
authors.lastname: Hox
authors.forename: Herman
authors.initials: H
authors.lastname: van Engeland
mesh_terms: D000328:Adult; D002648:Child; D002675:Child, Preschool; D003072:Cognition Disorders / Q000453:epidemiology* / Q000523:psychology; D015987:Effect Modifier, Epidemiologic; D006801:Humans; D012559:Schizophrenia / Q000145:classification / Q000453:epidemiology*; D012565:Schizophrenic Psychology; D012720:Severity of Illness Index; D012938:Social Perception; D013223:Statistics as Topic