title: Effects of Blocking D2/D3 Receptors on Mismatch Negativity and P3a Amplitude of Initially Antipsychotic Naïve, First Episode Schizophrenia Patients.
abstract: BACKGROUND
  Reduced mismatch negativity and P3a amplitude have been suggested to be among the core deficits in schizophrenia since the late 1970s. Blockade of dopamine D2 receptors play an important role in the treatment of schizophrenia. In addition, there is some evidence indicating that deficits in mismatch negativity and P3a amplitude are related to increased dopaminergic activity. This is the first study investigating the effect of amisulpride, a potent D2-antagonist, on mismatch negativity and P3a amplitude in a large group of antipsychotic-naïve, first-episode schizophrenia patients.
  
  
  METHODS
  Fifty-one antipsychotic-naïve, first-episode schizophrenia patients were tested in a mismatch negativity paradigm at baseline and after 6 weeks of treatment with amisulpride. We further examined 48 age- and gender-matched controls in this paradigm.
  
  
  RESULTS
  At baseline, the patients showed significantly reduced P3a amplitude compared with healthy controls, but no differences in mismatch negativity. Although the treatment with amisulpride significantly improved the patients' psychopathological (PANSS) and functional (GAF) scores, it did not influence their mismatch negativity amplitude, while also their reduced P3a amplitude persisted.
  
  
  CONCLUSIONS
  Our findings show that antipsychotic naïve, first-episode patients with schizophrenia have normal mismatch negativity yet reduced P3a amplitude compared with healthy controls. In spite of the fact that the 6-week amisulpride treatment improved the patients both clinically and functionally, it had no effect on either mismatch negativity or P3a amplitude. This suggests that even though there is a dopaminergic involvement in global functioning and symptomatology in schizophrenia, there is no such involvement in these particular measures of early information processing.
authors.affiliation: Center for Neuropsychiatric Schizophrenia Research, and Center for Clinical Intervention and Neuropsychiatric Schizophrenia Research, Copenhagen University Hospital, Psychiatric Center Glostrup, Glostrup, Denmark; Faculty of Health Sciences, Department of Neurology, Psychiatry, and Sensory Sciences, Copenhagen, University of Copenhagen. Signe@cnsr.dk.
authors.forename: Signe
authors.initials: S
authors.lastname: Düring
authors.affiliation: Center for Neuropsychiatric Schizophrenia Research, and Center for Clinical Intervention and Neuropsychiatric Schizophrenia Research, Copenhagen University Hospital, Psychiatric Center Glostrup, Glostrup, Denmark; Faculty of Health Sciences, Department of Neurology, Psychiatry, and Sensory Sciences, Copenhagen, University of Copenhagen.
authors.forename: Birte Yding
authors.initials: BY
authors.lastname: Glenthøj
authors.affiliation: Center for Neuropsychiatric Schizophrenia Research, and Center for Clinical Intervention and Neuropsychiatric Schizophrenia Research, Copenhagen University Hospital, Psychiatric Center Glostrup, Glostrup, Denmark; Faculty of Health Sciences, Department of Neurology, Psychiatry, and Sensory Sciences, Copenhagen, University of Copenhagen.
authors.forename: Bob
authors.initials: B
authors.lastname: Oranje
mesh_terms: D000293:Adolescent; D000328:Adult; D000077582:Amisulpride; D014150:Antipsychotic Agents / Q000627:therapeutic use*; D001921:Brain / Q000187:drug effects* / Q000503:physiopathology; D065127:Dopamine D2 Receptor Antagonists / Q000627:therapeutic use*; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D012559:Schizophrenia / Q000188:drug therapy* / Q000503:physiopathology; D012565:Schizophrenic Psychology; D013469:Sulpiride / Q000031:analogs & derivatives* / Q000627:therapeutic use; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D014150:Antipsychotic Agents; D065127:Dopamine D2 Receptor Antagonists; D017448:Receptors, Dopamine D2; D013469:Sulpiride; D000077582:Amisulpride
keywords: D2 blockade; First episode schizophrenia; mismatch negativity; psychophysiology