title: Duration mismatch negativity in biological relatives of patients with schizophrenia spectrum disorders.
abstract: BACKGROUND
  One of the most consistent findings in schizophrenia research over the past decade is a reduction in the amplitude of an auditory event-related brain potential known as mismatch negativity (MMN), which is generated whenever a deviant sound occurs in a background of repetitive auditory stimulation. The reduced amplitude of MMN in schizophrenia was first observed for deviant sounds that differ in duration relative to background standard sounds, and similar findings have been observed for sounds that are deviant in frequency. The aim of this study was to determine whether first-degree relatives of schizophrenia patients show a similar reduction in MMN amplitude to duration deviants.
  
  
  METHODS
  We measured MMN to duration increments (deviants 100 msec vs. standards 50 msec) in 22 medicated patients with a diagnosis in the schizophrenia spectrum, 17 individuals who were first-degree unaffected relatives of patients, and 21 healthy control subjects.
  
  
  RESULTS
  Mismatch negativity amplitude was reduced in patients and relatives compared with control subjects. There were no significant differences between patients and relatives. In contrast, the subsequent positive component, P3a, was larger in relatives compared with patients.
  
  
  CONCLUSIONS
  These findings suggest that a reduced MMN amplitude may be an endophenotype marker of the predisposition to schizophrenia.
authors.affiliation: Centre for Clinical Research in Neuropsychiatry, University of Western Australia, Nedlands, Australia.
authors.forename: Patricia T
authors.initials: PT
authors.lastname: Michie
authors.forename: Hamish
authors.initials: H
authors.lastname: Innes-Brown
authors.forename: Juanita
authors.initials: J
authors.lastname: Todd
authors.forename: Assen V
authors.initials: AV
authors.lastname: Jablensky
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001921:Brain / Q000503:physiopathology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory; D005190:Family; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D010898:Pitch Perception; D012559:Schizophrenia / Q000235:genetics* / Q000503:physiopathology*; D012565:Schizophrenic Psychology