title: Auditory mismatch negativity and P3a in response to duration and frequency changes in the early stages of psychosis.
abstract: BACKGROUND
  A shorter duration of untreated psychosis in patients with schizophrenia results in better symptomatic and functional outcomes. Therefore, identifying biological markers in the early stages of psychosis is an important step toward early detection and intervention. Mismatch negativity (MMN) and P3a are leading candidate biomarkers. MMN measures differ in their sensitivity to varying deviants. However, this has not been fully addressed in assessing the early stages of psychosis. In the current study, we examined MMN/P3a to duration deviant (dMMN/dP3a) and frequency deviant (fMMN/fP3a) in the early stages of psychosis. To our knowledge, this is the first study that examined both MMN/P3a to duration deviant (dMMN/dP3a) and frequency deviant (fMMN/fP3a) in the early stages of psychosis.
  
  
  METHODS
  Participants consisted of 20 patients with first episode schizophrenia (FES), 21 ultra-high risk (UHR) individuals, and 22 healthy controls (HC). We measured dMMN/dP3a and fMMN/fP3a ERP components by means of a 64 electrodes-cap for EEG recording, and we used two-tone auditory oddball paradigms with 2000 stimuli.
  
  
  RESULTS
  The amplitude of dMMN was significantly reduced in FES and UHR compared to HC. The amplitude of fMMN showed no significant difference among the three groups. The amplitudes of dP3a and fP3a were significantly reduced in FES and UHR compared to HC.
  
  
  CONCLUSIONS
  These findings suggest that dMMN may have higher sensitivity than fMMN whereas dP3a and fP3a may have similar sensitivity in the early stages of psychosis.
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan. Electronic address: t.nagai.md.psy@gmail.com.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Nagai
authors.forename: Mariko
authors.initials: M
authors.lastname: Tada
authors.forename: Kenji
authors.initials: K
authors.lastname: Kirihara
authors.forename: Noriaki
authors.initials: N
authors.lastname: Yahata
authors.forename: Ryuichiro
authors.initials: R
authors.lastname: Hashimoto
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Araki
authors.forename: Kiyoto
authors.initials: K
authors.lastname: Kasai
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D003265:Contingent Negative Variation / Q000502:physiology*; D004569:Electroencephalography; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D011571:Psychoacoustics; D012559:Schizophrenia / Q000175:diagnosis / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D013997:Time Factors; D055815:Young Adult
keywords: Event-related potential (ERP); First-episode schizophrenia (FES); Mismatch negativity (MMN); P3a; Ultra-high risk (UHR)