Abstract
IntroductionThe increase in electroencephalogram (EEG) alpha3/alpha2 frequency power ratio has been demonstrated as a biomarker characteristic of subjects with mild cognitive impairment (MCI) who will develop Alzheimer’s disease (AD).MethodsSeventy-four adult subjects with MCI underwent clinical and neuropsychological evaluation, EEG recording, and high-resolution 3D magnetic resonance imaging (MRI). This group has been evaluated after a three years follow-up. Twenty-seven of these subjects underwent perfusion single-photon emission computed tomography (SPECT) evaluation also. Increasing alpha3/alpha2 power ratio, was computed for each subject. Differences in EEG markers, cortical thickness, brain perfusion among the groups were estimated.ResultsIn the higher alpha3/alpha2 frequency power ratio group, greater memory impairment was correlated with greater cortical atrophy and lower perfusional rate in the temporo-parietal cortex. After a follow-up of three years, these patients converted in AD.ConclusionHigh EEG upper/low alpha power ratio was associated with cortical thinning and lower perfusion in the temporo-parietal lobe. Moreover, atrophy and lower perfusion rate were both significantly correlated with memory impairment in MCI subjects. The increase of EEG upper/low alpha frequency power ratio could be useful for identifying individuals at risk for progression to AD dementia and may be of value in the clinical context.
Highlights
The increase in electroencephalogram (EEG) alpha3/alpha2 frequency power ratio has been demonstrated as a biomarker characteristic of subjects with mild cognitive impairment (MCI) who will develop Alzheimer’s disease (AD)
We investigated the significance of the difference between the two groups (MCI at low and at high risk to develop AD) in socio-demographic, clinical, and cognitive features using the χ2 test for categorical variables and Student’s independent t test for continuous variables
The analysis of variance (ANOVA) analysis showed that there were no statistically significant differences between groups which paired for age, sex, white matter hyperintensities (WMHs) burden, education, or global cognitive level
Summary
The increase in electroencephalogram (EEG) alpha3/alpha frequency power ratio has been demonstrated as a biomarker characteristic of subjects with mild cognitive impairment (MCI) who will develop Alzheimer’s disease (AD). In line with recently published research criteria, it is becoming clear that the Moretti Alzheimer's Research & Therapy (2015) 7:80 of the integration of biomarkers for an early and highly predictive diagnosis, the electroencephalogram (EEG) could be a reliable tool [6]. It has been demonstrated that the increase of high alpha relative to low alpha power is both a reliable EEG marker of hippocampal atrophy [9] and predictive of conversion of patients with MCI to AD, but not to non-AD dementia [10]. Subjects with higher alpha3/alpha frequency power ratios showed a constant trend toward a lower perfusion than the low alpha3/alpha group associated with an increase of theta frequency power [11, 12]
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