title: Gray and white matter volume abnormalities in monozygotic and same-gender dizygotic twins discordant for schizophrenia.
abstract: BACKGROUND
  Whole brain tissue volume decreases in schizophrenia have been related to both genetic risk factors and disease-related (possibly nongenetic) factors; however, whether genetic and environmental risk factors in the brains of patients with schizophrenia are differentially reflected in gray or white matter volume change is not known.
  
  
  METHODS
  Magnetic resonance imaging (1.5 T) brain scans of 11 monozygotic and 11 same-gender dizygotic twin pairs discordant for schizophrenia were acquired and compared with 11 monozygotic and 11 same-gender dizygotic healthy control twin pairs.
  
  
  RESULTS
  Repeated-measures volume analysis of covariance revealed decreased whole brain volume in the patients with schizophrenia as compared with their co-twins and with healthy twin pairs. Decreased white matter volume was found in discordant twin pairs compared with healthy twin pairs, particularly in the monozygotic twin pairs. A decrease in gray matter was found in the patients compared with their co-twins and compared with the healthy twins.
  
  
  CONCLUSIONS
  The results suggest that the decreases in white matter volume reflect the increased genetic risk to develop schizophrenia, whereas the decreases in gray matter volume are related to environmental risk factors. Study of genes involved in the (maintenance) of white matter structures may be particularly fruitful in schizophrenia.
authors.affiliation: Rudolf Magnus Institute for Neuroscience, Department of Psychiatry, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Hilleke E
authors.initials: HE
authors.lastname: Hulshoff Pol
authors.forename: Rachel G H
authors.initials: RG
authors.lastname: Brans
authors.forename: Neeltje E M
authors.initials: NE
authors.lastname: van Haren
authors.forename: Hugo G
authors.initials: HG
authors.lastname: Schnack
authors.forename: Marieke
authors.initials: M
authors.lastname: Langen
authors.forename: Wim F C
authors.initials: WF
authors.lastname: Baaré
authors.forename: Clarine J
authors.initials: CJ
authors.lastname: van Oel
authors.forename: René S
authors.initials: RS
authors.lastname: Kahn
mesh_terms: D000328:Adult; D001284:Atrophy; D001921:Brain / Q000473:pathology*; D004200:Diseases in Twins; D004292:Dominance, Cerebral; D005260:Female; D005783:Gender Identity; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D012016:Reference Values; D012307:Risk Factors; D012559:Schizophrenia / Q000175:diagnosis* / Q000453:epidemiology; D018433:Twin Studies as Topic; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic