title: Mismatch negativity in schizophrenia: a family study.
abstract: BACKGROUND
  Mismatch negativity (MMN) is a measure of cortical activity that occurs in response to a change in auditory stimuli. We investigated whether MMN is a potential marker of genetic vulnerability to schizophrenia by comparing MMN in a group of patients with schizophrenia, their unaffected relatives, and controls.
  
  
  METHODS
  There are 25 schizophrenic patients, 37 of their unaffected first-degree relatives, and 20 unrelated controls that performed the MMN task. Linear regression with robust standard errors, and accounting for correlations within families, was employed to test for differences in MMN amplitude between the groups.
  
  
  RESULTS
  Patients had significantly smaller MMN amplitudes compared to both their unaffected relatives and controls at FZ (P<0.01) and at F3 (P=0.01), whereas relatives and controls did not differ at FZ or at F3. No differences were found between any of the groups at F4. Furthermore, we found no strong evidence that the MMN amplitude is a familial trait.
  
  
  CONCLUSIONS
  Our results confirm that the MMN amplitude is reduced in schizophrenia. However, the MMN does not show a significant familial influence and is normal among the unaffected relatives. We conclude that while the MMN is abnormal in patients with schizophrenia, it is a weak or unreliable marker of vulnerability when applied to subclinical populations, and therefore is unlikely to be an endophenotype for the disorder.
authors.affiliation: Institute of Psychiatry, PO Box 63, De Crespigny Park, Denmark Hill, London SE5 8AF, UK. e.bramon@iop.kcl.ac.uk
authors.forename: Elvira
authors.initials: E
authors.lastname: Bramon
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Croft
authors.forename: Colm
authors.initials: C
authors.lastname: McDonald
authors.forename: Gurkamal K
authors.initials: GK
authors.lastname: Virdi
authors.forename: John G
authors.initials: JG
authors.lastname: Gruzelier
authors.forename: Torsten
authors.initials: T
authors.lastname: Baldeweg
authors.forename: Pak C
authors.initials: PC
authors.lastname: Sham
authors.forename: Sophia
authors.initials: S
authors.lastname: Frangou
authors.forename: Robin M
authors.initials: RM
authors.lastname: Murray
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001143:Arousal / Q000502:physiology*; D001921:Brain / Q000503:physiopathology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004569:Electroencephalography; D004585:Electrooculography; D005133:Eye Movements / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D016014:Linear Models; D008297:Male; D012559:Schizophrenia / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology*; D012565:Schizophrenic Psychology