title: MMN/P3a deficits in first episode psychosis: comparing schizophrenia-spectrum and affective-spectrum subgroups.
abstract: BACKGROUND
  Reduced mismatch negativity (MMN) and P3a amplitudes are neurophysiological biomarkers for schizophrenia that index deviance detection and the orienting response, respectively. First-episode psychosis (FEP) patients show reduced amplitudes of the 'MMN/P3a complex', but it is unclear whether this occurs across the FEP spectrum.
  
  
  METHODS
  Fifty-three young people (17-36 years) were assessed: 17 FEP affective-spectrum (bipolar disorder with psychotic features and major depressive disorder with psychotic features), 18 FEP schizophrenia-spectrum (schizophrenia, schizoaffective disorder, and schizophreniform disorder), and 18 healthy controls. MMN/P3a was acquired during a two-tone, auditory paradigm with 8% duration deviants. Clinical, psychosocial and neuropsychological assessments were also undertaken.
  
  
  RESULTS
  FEP schizophrenia- and FEP affective-spectrum showed significantly reduced fronto-central MMN and central P3a amplitudes compared to controls. FEP subgroups also showed significantly poorer cognitive and psychosocial functioning. The combined FEP sample showed significant correlations between fronto-central MMN amplitudes and cognitive measures.
  
  
  CONCLUSIONS
  FEP schizophrenia-spectrum and FEP affective-spectrum were similarly impaired in two biomarkers for schizophrenia. FEP subgroups showed impairments in fronto-central MMN consistent with chronic patients. Similarly, both subgroups showed reductions in P3a; although the affective subgroup showed an 'intermediate' frontal response. These findings suggest that FEP patients with both affective and schizophrenia spectrum diagnoses share common neurobiological disturbances in deviance detection/orienting processes in the early phase of illness.
authors.affiliation: Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, Sydney, Australia. manreena.kaur@sydney.edu.au
authors.forename: Manreena
authors.initials: M
authors.lastname: Kaur
authors.forename: Robert A
authors.initials: RA
authors.lastname: Battisti
authors.forename: Philip B
authors.initials: PB
authors.lastname: Ward
authors.forename: Arnab
authors.initials: A
authors.lastname: Ahmed
authors.forename: Ian B
authors.initials: IB
authors.lastname: Hickie
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Hermens
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D014150:Antipsychotic Agents / Q000627:therapeutic use; D001931:Brain Mapping; D003265:Contingent Negative Variation / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D019964:Mood Disorders / Q000188:drug therapy / Q000503:physiopathology*; D009483:Neuropsychological Tests; D011618:Psychotic Disorders / Q000188:drug therapy / Q000503:physiopathology*; D012559:Schizophrenia / Q000188:drug therapy / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D013057:Spectrum Analysis; D013223:Statistics as Topic; D055815:Young Adult
chemical_list: D014150:Antipsychotic Agents