title: Reduced duration mismatch negativity in adolescents with psychotic symptoms: further evidence for mismatch negativity as a possible biomarker for vulnerability to psychosis.
abstract: BACKGROUND
  Deficits in the mismatch negativity (MMN) and P3a components are the most reliable and robust findings in schizophrenia. These abnormalities have also been recently documented in individuals clinically at risk for psychosis, indicating that the MMN may be a potential biomarker for psychosis. However, the at risk samples included in MMN studies are characterised by pre-existing clinical symptomatology and significant functional decline which are related to MMN amplitude. These factors may be potential confounds in determining whether deficient MMN is present prior to clinical manifestation of the disorder. Therefore, investigating the MMN in the extended psychosis phenotype comprising adolescents with psychotic symptoms from the general population may provide important information on whether abnormal MMN is apparent in the earliest stages of risk.
  
  
  METHODS
  Thirty six adolescents completed a duration deviant MMN task. Fourteen adolescents with psychotic symptoms comprised the at risk group and 22 with no psychotic symptoms comprised the Controls. The task consisted of 85% standard tones (25 ms) and 15% deviant tones (50 ms). The groups were compared on MMN and P3a amplitude and latency across frontocentral and temporal electrodes.
  
  
  RESULTS
  Adolescents with psychotic symptoms were characterised by a reduction in MMN amplitude at frontal and temporal regions compared to the controls.
  
  
  CONCLUSIONS
  This is the first study to demonstrate impaired auditory discrimination for duration deviant tones in nonclinical adolescents with psychotic symptoms. These findings suggest that MMN amplitude may be a possible biomarker for vulnerability to psychosis.
authors: Department of Psychiatry, Royal College of Surgeons in Ireland, Dublin, Ireland. marycannon@rcsi.ie.
authors: Jennifer R
authors: JR
authors: Murphy
authors: Caroline
authors: C
authors: Rawdon
authors: Ian
authors: I
authors: Kelleher
authors: Deirdre
authors: D
authors: Twomey
authors: Patrick S
authors: PS
authors: Markey
authors: Mary
authors: M
authors: Cannon
authors: Richard Ap
authors: RA
authors: Roche
mesh_terms: D000293:Adolescent; D015415:Biomarkers; D001921:Brain / Q000502:physiology / Q000503:physiopathology; D016022:Case-Control Studies; D002648:Child; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D007406:Interview, Psychological; D008297:Male; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000503:physiopathology*; D012307:Risk Factors
chemical_list: D015415:Biomarkers
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