title: Brain-wide slowing of spontaneous alpha rhythms in mild cognitive impairment.
abstract: The neurophysiological changes associated with Alzheimer's Disease (AD) and Mild Cognitive Impairment (MCI) include an increase in low frequency activity, as measured with electroencephalography or magnetoencephalography (MEG). A relevant property of spectral measures is the alpha peak, which corresponds to the dominant alpha rhythm. Here we studied the spatial distribution of MEG resting state alpha peak frequency and amplitude values in a sample of 27 MCI patients and 24 age-matched healthy controls. Power spectra were reconstructed in source space with linearly constrained minimum variance beamformer. Then, 88 Regions of Interest (ROIs) were defined and an alpha peak per ROI and subject was identified. Statistical analyses were performed at every ROI, accounting for age, sex and educational level. Peak frequency was significantly decreased (p < 0.05) in MCIs in many posterior ROIs. The average peak frequency over all ROIs was 9.68 ± 0.71 Hz for controls and 9.05 ± 0.90 Hz for MCIs and the average normalized amplitude was (2.57 ± 0.59)·10(-2) for controls and (2.70 ± 0.49)·10(-2) for MCIs. Age and gender were also found to play a role in the alpha peak, since its frequency was higher in females than in males in posterior ROIs and correlated negatively with age in frontal ROIs. Furthermore, we examined the dependence of peak parameters with hippocampal volume, which is a commonly used marker of early structural AD-related damage. Peak frequency was positively correlated with hippocampal volume in many posterior ROIs. Overall, these findings indicate a pathological alpha slowing in MCI.
authors.affiliation: Laboratory of Cognitive and Computational Neuroscience (UCM-UPM), Centre for Biomedical Technology Madrid, Spain ; Department of Applied Physics III, Faculty of Physics, Complutense University of Madrid Madrid, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Garcés
authors.affiliation: MEG Unit, Brain Imaging Center, Goethe University Frankfurt, Germany ; Max-Planck Institute for Brain Research Frankfurt, Germany ; Institute of Computer Science, Faculty of Mathematics and Computer Science, University of Tartu Tartu, Estonia.
authors.forename: Raul
authors.initials: R
authors.lastname: Vicente
authors.affiliation: MEG Unit, Brain Imaging Center, Goethe University Frankfurt, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Wibral
authors.affiliation: Laboratory of Cognitive and Computational Neuroscience (UCM-UPM), Centre for Biomedical Technology Madrid, Spain.
authors.forename: Jose Ángel
authors.initials: JÁ
authors.lastname: Pineda-Pardo
authors.affiliation: Laboratory of Cognitive and Computational Neuroscience (UCM-UPM), Centre for Biomedical Technology Madrid, Spain ; Department of Basic Psychology II, Complutense University of Madrid Madrid, Spain.
authors.forename: Maria Eugenia
authors.initials: ME
authors.lastname: López
authors.affiliation: Laboratory of Cognitive and Computational Neuroscience (UCM-UPM), Centre for Biomedical Technology Madrid, Spain ; Department of Basic Psychology II, Complutense University of Madrid Madrid, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Aurtenetxe
authors.affiliation: Neurology Department, San Carlos Clinical Hospital Madrid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Marcos
authors.affiliation: Memory Decline Prevention Center, Ayuntamiento de Madrid Madrid, Spain.
authors.forename: Maria Emiliana
authors.initials: ME
authors.lastname: de Andrés
authors.affiliation: Radiology Department, San Carlos Clinical Hospital Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Yus
authors.affiliation: Department of Applied Physics III, Faculty of Physics, Complutense University of Madrid Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Sancho
authors.affiliation: Laboratory of Cognitive and Computational Neuroscience (UCM-UPM), Centre for Biomedical Technology Madrid, Spain ; Department of Basic Psychology II, Complutense University of Madrid Madrid, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Maestú
authors.affiliation: Laboratory of Cognitive and Computational Neuroscience (UCM-UPM), Centre for Biomedical Technology Madrid, Spain ; Department of Psychiatry and Medical Psychology, Faculty of Medicine, Complutense University of Madrid Madrid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Fernández
keywords: alpha peak; hippocampal volume; magnetoencephalography; mild cognitive impairment; slowing