title: Slowing of EEG background activity in Parkinson's and Alzheimer's disease with early cognitive dysfunction.
abstract: BACKGROUND
  Slowing of the electroencephalogram (EEG) is frequent in Parkinson's (PD) and Alzheimer's disease (AD) and correlates with cognitive decline. As overlap pathology plays a role in the pathogenesis of dementia, it is likely that demented patients in PD show similar physiological alterations as in AD.
  
  
  OBJECTIVE
  To analyze distinctive quantitative EEG characteristics in early cognitive dysfunction in PD and AD.
  
  
  METHODS
  Forty patients (20 PD- and 20 AD patients with early cognitive impairment) and 20 normal controls (NC) were matched for gender, age, and education. Resting state EEG was recorded from 256 electrodes. Relative power spectra, median frequency (4-14 Hz), and neuropsychological outcome were compared between groups.
  
  
  RESULTS
  Relative theta power in left temporal region and median frequency separated the three groups significantly (p = 0.002 and p < 0.001). Relative theta power was increased and median frequency reduced in patients with both diseases compared to NC. Median frequency was higher in AD than in PD and classified groups significantly (p = 0.02).
  
  
  CONCLUSIONS
  Increase of theta power in the left temporal region and a reduction of median frequency were associated with presence of AD or PD. PD patients are characterized by a pronounced slowing as compared to AD patients. Therefore, in both disorders EEG slowing might be a useful biomarker for beginning cognitive decline.
authors.affiliation: Department of Neurology, Hospitals of University of Basel , Basel , Switzerland.
authors.forename: Nina
authors.initials: N
authors.lastname: Benz
authors.affiliation: Department of Neurology, Hospitals of University of Basel , Basel , Switzerland.
authors.forename: Florian
authors.initials: F
authors.lastname: Hatz
authors.affiliation: Department of Neurology, Hospitals of University of Basel , Basel , Switzerland ; Swiss Tropical and Public Health Institute, University of Basel , Basel , Switzerland.
authors.forename: Habib
authors.initials: H
authors.lastname: Bousleiman
authors.affiliation: Memory Clinic, University Center for Medicine of Aging Basel, Felix Platter Hospital , Basel , Switzerland.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Ehrensperger
authors.affiliation: Department of Neurology, Hospitals of University of Basel , Basel , Switzerland.
authors.forename: Ute
authors.initials: U
authors.lastname: Gschwandtner
authors.affiliation: Department of Neurology, Hospitals of University of Basel , Basel , Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Hardmeier
authors.affiliation: Department of Neurology, Hospitals of University of Basel , Basel , Switzerland.
authors.forename: Stephan
authors.initials: S
authors.lastname: Ruegg
authors.affiliation: Swiss Tropical and Public Health Institute, University of Basel , Basel , Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Schindler
authors.affiliation: Department of Neurology, Hospitals of University of Basel , Basel , Switzerland.
authors.forename: Ronan
authors.initials: R
authors.lastname: Zimmermann
authors.affiliation: Memory Clinic, University Center for Medicine of Aging Basel, Felix Platter Hospital , Basel , Switzerland.
authors.forename: Andreas Urs
authors.initials: AU
authors.lastname: Monsch
authors.affiliation: Department of Neurology, Hospitals of University of Basel , Basel , Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Fuhr
keywords: Alzheimer’s disease; Parkinson’s disease; dementia; mild cognitive impairment; neuropsychology; quantitative electroencephalography