title: Mismatch negativity and p3a/reorienting complex in subjects with schizophrenia or at-risk mental state.
abstract: BACKGROUND
  We measured duration mismatch negativity (dMMN), P3a, and reorienting negativity (RON) in subjects with at-risk mental state (ARMS), patients with first-episode or chronic schizophrenia, and healthy volunteers. The main interest was to determine if these event-related potentials provide a biomarker associated with progression to overt schizophrenia in ARMS subjects.
  
  
  METHODS
  Nineteen ARMS subjects meeting the criteria of the Comprehensive Assessment of ARMS, 38 patients with schizophrenia (19 first-episode and 19 chronic), and 19 healthy controls participated in the study. dMMN, P3a, and RON were measured with an auditory odd-ball paradigm at baseline.
  
  
  RESULTS
  During the follow-up period (2.2 years), 4 out of the 19 ARMS subjects transitioned to schizophrenia (Converters) while 15 did not (non-Converters). dMMN amplitudes of Converters were significantly smaller than those of non-Converters at frontal and central electrodes before onset of illness. dMMN amplitudes of non-Converters did not differ from those of healthy controls, while Converters showed significantly smaller dMMN amplitudes compared to control subjects. RON amplitudes were also reduced at frontal and central electrodes in subjects with schizophrenia, but not ARMS. Converter subjects tended to show smaller RON amplitudes compared to non-Converters.
  
  
  CONCLUSIONS
  Our data confirm that diminished dMMN amplitudes provide a biomarker, which is present before and after the development of psychosis. In this respect, RON amplitudes may also be useful, as suggested for the first time based on longitudinal observations.
authors.affiliation: Department of Neuropsychiatry, University of Toyama Graduate School of Medicine and Pharmaceutical Science , Toyama , Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Higuchi
authors.affiliation: Department of Neuropsychiatry, University of Toyama Graduate School of Medicine and Pharmaceutical Science , Toyama , Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Seo
authors.affiliation: Department of Neuropsychiatry, University of Toyama Graduate School of Medicine and Pharmaceutical Science , Toyama , Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Miyanishi
authors.affiliation: Department of Neuropsychiatry, Kanazawa Medical University , Ishikawa , Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kawasaki
authors.affiliation: Department of Neuropsychiatry, University of Toyama Graduate School of Medicine and Pharmaceutical Science , Toyama , Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Suzuki
authors.affiliation: Department of Clinical Research Promotion, National Center Hospital, National Center of Neurology and Psychiatry , Tokyo , Japan.
authors.forename: Tomiki
authors.initials: T
authors.lastname: Sumiyoshi
keywords: event-related potentials; mismatch negativity; prodromal; reorienting negativity; schizophrenia