EEG upper/low alpha frequency power ratio relates to temporo-parietal brain atrophy and memory performances in mild cognitive impairment.

Davide V Moretti,Orazio Zanetti,Giovanni B Frisoni,Donata Paternicò,Giuliano Binetti

doi:10.3389/fnagi.2013.00063

Davide V Moretti, Orazio Zanetti + Show 3 more

Open Access

https://doi.org/10.3389/fnagi.2013.00063

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Abstract

Objective: Temporo-parietal cortex thinning is associated to mild cognitive impairment (MCI) due to Alzheimer disease (AD). The increase of EEG upper/low alpha power ratio has been associated with AD-converter MCI subjects. We investigated the association of alpha3/alpha2 ratio with patterns of cortical thickness in MCI.Materials and Methods: Seventy-four adult subjects with MCI underwent clinical and neuropsychological evaluation, electroencephalogram (EEG) recording and high resolution 3D magnetic resonance imaging. Alpha3/alpha2 power ratio as well as cortical thickness was computed for each subject. Three MCI groups were detected according to increasing tertile values of upper/low alpha power ratio. Difference of cortical thickness among the groups was estimated. Pearson’s r was used to assess the topography of the correlation between cortical thinning and memory impairment.Results: High upper/low alpha power ratio group had total cortical gray matter volume reduction of 471 mm2 than low upper/low alpha power ratio group (p < 0.001). Upper/low alpha group showed a similar but less marked pattern (160 mm2) of cortical thinning when compared to middle upper/low alpha power ratio group (p < 0.001). Moreover, high upper/low alpha group had wider cortical thinning than other groups, mapped to the Supramarginal and Precuneus bilaterally. Finally, in high upper/low alpha group temporo-parietal cortical thickness was correlated to memory performance. No significant cortical thickness differences was found between middle and low alpha3/alpha2 power ratio groups.Conclusion: High EEG upper/low alpha power ratio was associated with temporo-parietal cortical thinning and memory impairment in MCI subjects. The combination of EEG upper/low alpha ratio and cortical thickness measure could be useful for identifying individuals at risk for progression to AD dementia and may be of value in clinical context.

Highlights

The mild cognitive impairment (MCI) commonly represent the “at-risk” state of developing dementia
High EEG upper/low alpha power ratio was associated with temporo-parietal cortical thinning and memory impairment in MCI subjects
The combination of EEG upper/low alpha ratio and cortical thickness measure could be useful for identifying individuals at risk for progression to Alzheimer’s disease (AD) dementia and may be of value in clinical context

Summary

Introduction

The mild cognitive impairment (MCI) commonly represent the “at-risk” state of developing dementia. In line with recently published research criteria, it is becoming clear that the integration of different biomarkers is a milestone for a correct and early diagnosis of AD (Dubois et al, 2007; Albert et al, 2011). The latter biomarkers have a good sensibility in identifying subjects with a neurodegenerative disorders at high risk to convert in dementia, but they lack a reliable specificity that allow a clear-cut diagnosis of the different subtypes of dementias. Subjects with cognitive decline have shown early atrophy and loss of gray matter in cortical specific brain areas (Frisoni et al, 2007, 2009), including including precuneus, hippocampal, medial temporal, and parietal lobes.

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