title: Hippocampal volume reduction in schizophrenia: effects of genetic risk and pregnancy and birth complications.
abstract: BACKGROUND
  Hippocampal volume reduction has been repeatedly demonstrated in schizophrenia. The relative contribution of genetic and environmental factors to this is unclear.
  
  
  METHODS
  To address this question, we compared volumetric measurements of the left and right hippocampus, obtained using stereological methods from brain MRI scans, from two groups of patients with schizophrenia as well as healthy controls (n = 26). Patients (n = 27) in the first group, had no family history of schizophrenia and had experienced severe pregnancy and birth complications (PBCs). The second group comprised of patients (n = 21) without a history of severe PBCs from families multiply affected with schizophrenia.
  
  
  RESULTS
  Reduction of the left hippocampal volume was associated with the diagnosis of schizophrenia but was present only in patients with a history of severe PBCs; in this group the smaller hippocampal volume, the earlier the onset of psychosis.
  
  
  CONCLUSIONS
  Our findings suggest that environmental factors, in this case severe PBCs, make a significant contribution to hippocampal abnormalities in schizophrenia.
authors.affiliation: Department of Psychological Medicine, Institute of Psychiatry, London, UK.
authors.forename: N
authors.initials: N
authors.lastname: Stefanis
authors.forename: S
authors.initials: S
authors.lastname: Frangou
authors.forename: J
authors.initials: J
authors.lastname: Yakeley
authors.forename: T
authors.initials: T
authors.lastname: Sharma
authors.forename: P
authors.initials: P
authors.lastname: O'Connell
authors.forename: K
authors.initials: K
authors.lastname: Morgan
authors.forename: T
authors.initials: T
authors.lastname: Sigmudsson
authors.forename: M
authors.initials: M
authors.lastname: Taylor
authors.forename: R
authors.initials: R
authors.lastname: Murray
mesh_terms: D000328:Adult; D004777:Environment; D005260:Female; D006624:Hippocampus / Q000002:abnormalities*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D007744:Obstetric Labor Complications; D011247:Pregnancy; D011248:Pregnancy Complications; D012307:Risk Factors; D012559:Schizophrenia / Q000175:diagnosis* / Q000235:genetics*; D012720:Severity of Illness Index