title: Mismatch negativity in schizophrenia: a meta-analysis.
abstract: BACKGROUND
  Mismatch negativity (MMN) is an auditory event-related potential that provides an index of automatic context-dependent information processing and auditory sensory memory. Many studies have reported abnormalities in the generation of MMN in schizophrenia. The objective of this study was to assess the magnitude of this deficit and associated factors.
  
  
  METHODS
  Studies of MMN in schizophrenia were identified and included in a meta-analysis to estimate the mean effect size. Effects of duration of illness, gender ratio, age of patients, type of MMN (duration versus frequency MMN) and characteristics of the test paradigms (deviant probability, magnitude of standard-deviant difference) on effect size were assessed.
  
  
  RESULTS
  Of 62 identified studies 32 met our inclusion criteria. The mean effect size was 0.99 (95% confidence intervals: 0.79, 1.29). Overall, no specific factor was significantly associated with MMN deficits, although MMN to stimuli differing in duration appeared more impaired in schizophrenia than MMN to frequency deviants. In addition, effect sizes of frequency MMN were significantly correlated with duration of illness.
  
  
  CONCLUSIONS
  MMN deficits are a robust feature in chronic schizophrenia and indicate abnormalities in automatic context-dependent auditory information processing and auditory sensory memory in these patients. Reports of normal MMN in first-episode schizophrenia and the association of deficits in frequency MMN with illness duration suggest that MMN may index ongoing neuropathological changes in the auditory cortex in schizophrenia.
authors.affiliation: University of Zurich, Department of Psychiatric Research, Psychiatric University Hospital Zurich, Switzerland. umbricht@bli.unizh.ch
authors.forename: Daniel
authors.initials: D
authors.lastname: Umbricht
authors.forename: Sanya
authors.initials: S
authors.lastname: Krljes
mesh_terms: D001303:Auditory Cortex / Q000503:physiopathology; D002908:Chronic Disease; D003265:Contingent Negative Variation / Q000502:physiology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D006801:Humans; D011939:Mental Recall / Q000502:physiology; D012016:Reference Values; D012559:Schizophrenia / Q000175:diagnosis* / Q000503:physiopathology; D012565:Schizophrenic Psychology; D012680:Sensitivity and Specificity