title: EEG correlates of a mental arithmetic task in patients with first episode schizophrenia and schizoaffective disorder.
abstract: OBJECTIVE
  To evaluate the spectral power of the cortical bands in patients with first episode schizophrenia and schizoaffective disorder at rest and during the performance of a mental arithmetic task.
  
  
  METHODS
  We analyzed EEG spectral power (SP) in the resting state and subsequently while counting down from 200 in steps of 7, in 32 first episode schizophrenia patients (SZ), 32 patients with first episode schizoaffective disorder (SA) and healthy controls (HC, n=40). Behavioral parameters such as accuracy and counting speed were also evaluated.
  
  
  RESULTS
  Both SZ and SA patients were slower in counting than HC, no difference was obtained in the accuracy and counting speed in the patient groups. In the resting state patients showed elevated midline theta power, off-midline anterior beta 2 power and decreased central/posterior alpha power. The SA group occupied an intermediate position between the schizophrenia patients and controls. In task performance patients lacked a typical increase of midline theta, left anterior beta 2, and anterior gamma power; however, schizoaffective patients demonstrated a growing trend of power in the gamma band in left anterior off-midline sites similar to HC. Moreover, alpha power was less inhibited in schizoaffective patients and more pronounced in schizophrenia patients indicating distinct inhibitory mechanisms in these psychotic disorders.
  
  
  CONCLUSIONS
  Patients with SA demonstrate less alteration in the spectral power of bands at rest than SZ, and present spectral power changes during cognitive task performance close to the controls.
  
  
  CONCLUSIONS
  Our study contributes to the present evidence on the neurophysiological distinction between schizophrenia and schizoaffective disorder.
authors.affiliation: Institute of Higher Nervous Activity and Neurophysiology Russian Academy of Science, Moscow, Russian Federation.
authors.forename: Zhanna
authors.initials: Z
authors.lastname: Garakh
authors.affiliation: Moscow Research Institute of Psychiatry, Moscow, Russian Federation; Institute of Medical Psychology, Human Science Centre, Ludwig-Maximilian University, Munich, Germany; National Institute of Mental Health, Klecany, Czech Republic/Prague Psychiatric Center, 3rd Faculty of Medicine, Charles University in Prague, Czech Republic. Electronic address: yuliya.zaytseva@gmail.com.
authors.forename: Yuliya
authors.initials: Y
authors.lastname: Zaytseva
authors.affiliation: Moscow Research Institute of Psychiatry, Moscow, Russian Federation.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kapranova
authors.affiliation: Department of Neurology and Center of Clinical Neuroscience, Charles University in Prague, 1st Faculty of Medicine and General University Hospital, Prague, Czech Republic; Institute of Neuropsychiatric Care, Prague, Czech Republic.
authors.forename: Ondrej
authors.initials: O
authors.lastname: Fiala
authors.affiliation: National Institute of Mental Health, Klecany, Czech Republic/Prague Psychiatric Center, 3rd Faculty of Medicine, Charles University in Prague, Czech Republic.
authors.forename: Jiri
authors.initials: J
authors.lastname: Horacek
authors.affiliation: Moscow Research Institute of Psychiatry, Moscow, Russian Federation.
authors.forename: Alexander
authors.initials: A
authors.lastname: Shmukler
authors.affiliation: Moscow Research Institute of Psychiatry, Moscow, Russian Federation.
authors.forename: Isaac Ya
authors.initials: IY
authors.lastname: Gurovich
authors.affiliation: Institute of Higher Nervous Activity and Neurophysiology Russian Academy of Science, Moscow, Russian Federation.
authors.forename: Valeria B
authors.initials: VB
authors.lastname: Strelets
mesh_terms: D000293:Adolescent; D000328:Adult; D000513:Alpha Rhythm / Q000502:physiology; D001611:Beta Rhythm / Q000502:physiology; D001931:Brain Mapping; D016022:Case-Control Studies; D003071:Cognition / Q000502:physiology; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D008875:Middle Aged; D011618:Psychotic Disorders / Q000503:physiopathology*; D012146:Rest / Q000502:physiology; D012559:Schizophrenia / Q000503:physiopathology*; D013647:Task Performance and Analysis; D013826:Theta Rhythm / Q000502:physiology; D055815:Young Adult
keywords: EEG spectral power; First psychotic episode; Mental arithmetic task; Resting state; Schizoaffective disorder; Schizophrenia