title: Abnormalities of auditory event-related potentials in schizophrenia prior to treatment.
abstract: BACKGROUND
  P300 amplitude reduction is a consistent finding in schizophrenic patients, but it is unclear if this abnormality predates neuroleptic treatment or is present at onset of illness.
  
  
  METHODS
  Auditory event-related potentials (ERPs), during a standard oddball paradigm, were recorded from 45 neuroleptic-naive schizophrenics, 56 drug-free, previously treated schizophrenics, and 73 healthy normal controls. Forty-seven of the schizophrenic subjects had their first episode within the past year.
  
  
  RESULTS
  N200 amplitude did not differ among groups. P300 amplitude was significantly smaller in both neuroleptic-naive and previously treated schizophrenic groups compared to the control groups. There were no significant differences between the two schizophrenic groups in P300 amplitude. N200 and P300 latency were prolonged in previously treated schizophrenics compared to neuroleptic-naive schizophrenics and normal controls.
  
  
  CONCLUSIONS
  The present study suggests that ERP abnormalities, especially P300 amplitude reduction, are already present prior to the administration of neuroleptic medication in the earliest stage of schizophrenia.
authors.affiliation: Department of Neuropsychiatry, University of the Ryukyus, Okinawa, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Hirayasu
authors.forename: N
authors.initials: N
authors.lastname: Asato
authors.forename: H
authors.initials: H
authors.lastname: Ohta
authors.forename: H
authors.initials: H
authors.lastname: Hokama
authors.forename: H
authors.initials: H
authors.lastname: Arakaki
authors.forename: C
authors.initials: C
authors.lastname: Ogura
mesh_terms: D000328:Adult; D004569:Electroencephalography / Q000187:drug effects; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D012559:Schizophrenia / Q000188:drug therapy / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D012727:Sex Characteristics