title: Aberrant Current Source-Density and Lagged Phase Synchronization of Neural Oscillations as Markers for Emerging Psychosis.
abstract: BACKGROUND
  Converging evidence indicates that neural oscillations coordinate activity across brain areas, a process which is seemingly perturbed in schizophrenia. In particular, beta (13-30 Hz) and gamma (30-50 Hz) oscillations were repeatedly found to be disturbed in schizophrenia and linked to clinical symptoms. However, it remains unknown whether abnormalities in current source density (CSD) and lagged phase synchronization of oscillations across distributed regions of the brain already occur in patients with an at-risk mental state (ARMS) for psychosis.
  
  
  METHODS
  To further elucidate this issue, we assessed resting-state EEG data of 63 ARMS patients and 29 healthy controls (HC). Twenty-three ARMS patients later made a transition to psychosis (ARMS-T) and 40 did not (ARMS-NT). CSD and lagged phase synchronization of neural oscillations across brain areas were assessed using eLORETA and their relationships to neurocognitive deficits and clinical symptoms were analyzed using linear mixed-effects models.
  
  
  RESULTS
  ARMS-T patients showed higher gamma activity in the medial prefrontal cortex compared to HC, which was associated with abstract reasoning abilities in ARMS-T. Furthermore, in ARMS-T patients lagged phase synchronization of beta oscillations decreased more over Euclidian distance compared to ARMS-NT and HC. Finally, this steep spatial decrease of phase synchronicity was most pronounced in ARMS-T patients with high positive and negative symptoms scores.
  
  
  CONCLUSIONS
  These results indicate that patients who will later make the transition to psychosis are characterized by impairments in localized and synchronized neural oscillations providing new insights into the pathophysiological mechanisms of schizophrenic psychoses and may be used to improve the prediction of psychosis.
authors.affiliation: University of Basel Psychiatric Clinics, Center for Gender Research and Early Detection, Basel;
authors.forename: Avinash
authors.initials: A
authors.lastname: Ramyead
authors.affiliation: Neuropsychopharmacology and Brain Imaging Research Unit, Psychiatric University Hospital, Zurich;
authors.forename: Michael
authors.initials: M
authors.lastname: Kometer
authors.affiliation: University of Basel Psychiatric Clinics, Center for Gender Research and Early Detection, Basel;
authors.forename: Erich
authors.initials: E
authors.lastname: Studerus
authors.affiliation: University of Basel Psychiatric Clinics, Center for Gender Research and Early Detection, Basel;
authors.forename: Susan
authors.initials: S
authors.lastname: Koranyi
authors.affiliation: University of Basel Psychiatric Clinics, Center for Gender Research and Early Detection, Basel;
authors.forename: Sarah
authors.initials: S
authors.lastname: Ittig
authors.affiliation: Department of Neurology, University Hospital Basel, Basel, Switzerland.
authors.forename: Ute
authors.initials: U
authors.lastname: Gschwandtner
authors.affiliation: Department of Neurology, University Hospital Basel, Basel, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Fuhr
authors.affiliation: University of Basel Psychiatric Clinics, Center for Gender Research and Early Detection, Basel; anita.riecher@upkbs.ch.
authors.forename: Anita
authors.initials: A
authors.lastname: Riecher-Rössler
mesh_terms: D000293:Adolescent; D000328:Adult; D001611:Beta Rhythm / Q000502:physiology; D015415:Biomarkers; D002540:Cerebral Cortex / Q000503:physiopathology*; D004569:Electroencephalography / Q000379:methods*; D058407:Electroencephalography Phase Synchronization / Q000502:physiology; D005260:Female; D065818:Gamma Rhythm / Q000502:physiology; D006801:Humans; D008297:Male; D062706:Prodromal Symptoms; D011618:Psychotic Disorders / Q000175:diagnosis / Q000503:physiopathology*; D012306:Risk; D055815:Young Adult
chemical_list: D015415:Biomarkers
keywords: EEG; at-risk mental state (ARMS); resting state; schizophrenia