title: Frequency power and coherence of electroencephalography are correlated with the severity of Alzheimer's disease: A multicenter analysis in Taiwan.
abstract: OBJECTIVE
  Slowing of average electroencephalography (EEG) frequency in Alzheimer's disease (AD) is well established, but whether EEG changes are able to reflect the severity of AD is uncertain. We attempt to establish quantitative EEG parameters that are suitable for evaluating AD in clinical practice.
  
  
  METHODS
  Ninety-five patients with newly diagnosed AD at different stages from four neurologic institutes were enrolled for the study. Standard scalp resting EEG data were collected for quantitative analysis. Global band power ratio and interhemispheric alpha band coherence were calculated.
  
  
  RESULTS
  Patients with advanced AD had a greater slow-to-fast wave power ratio. Among several power ratio parameters, global theta and delta to alpha and beta band power ratio showed the best correlation with stages of AD (p < 0.05 between any two patient groups). Patients with advanced AD had decreased coherence in multiple brain regions. The phenomenon was most prominent in the centroparietal region (p < 0.05 between any two patient groups).
  
  
  CONCLUSIONS
  Increased global slow-to-fast power ratio and decreased centroparietal interhemispheric alpha band coherence are strongly correlated with disease progress in AD patients. These two quantitative EEG parameters may help evaluate AD patients in daily clinical practice. Global power ratio changes may suggest a shift of dominant frequency, and decreased interhemispheric alpha band coherence may suggest functional disconnection and corpus callosum abnormalities in AD patients.
authors: Graduate Institute of Biomedical Informatics, Taipei Medical University, Taipei, Taiwan; Department of Neurology, Taipei Medical University-Shuang Ho Hospital, Taipei, Taiwan.
authors: Chih-Chung
authors: CC
authors: Chen
authors: Graduate Institute of Biomedical Informatics, Taipei Medical University, Taipei, Taiwan.
authors: Chien-Yeh
authors: CY
authors: Hsu
authors: Graduate Institute of Biomedical Informatics, Taipei Medical University, Taipei, Taiwan. Electronic address: hwchiu@tmu.edu.tw.
authors: Hung-Wen
authors: HW
authors: Chiu
authors: Department of Neurology, Taipei Medical University-Shuang Ho Hospital, Taipei, Taiwan.
authors: Chaur-Jong
authors: CJ
authors: Hu
authors: Graduate Institute of Biomedical Informatics, Taipei Medical University, Taipei, Taiwan; Department of Biomedical Engineering, Yuanpei University, HsinChu, Taiwan.
authors: Tsung-Chieh
authors: TC
authors: Lee
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013624:Taiwan
keywords: Alzheimer's disease; coherence; dementia; spectral analysis