Brain oscillatory patterns in mild cognitive impairment due to Alzheimer's and Parkinson's disease: An exploratory high-density EEG study

Objective: We investigated brain cortical activity alterations, using a resting-state 256-channel highdensity EEG (hd-EEG), in Alzheimer's (AD) and Parkinson's (PD) disease subjects with mild cognitive impairment (MCI) and correlations between quantitative spectral EEG parameters and the global cognitive status assessed by Montreal Cognitive Assessment (MoCA) score. Methods: Fifteen AD-MCI, eleven PD-MCI and ten age-matched healthy-controls (HC) underwent hd-EEG recordings and neuropsychological assessment. Cerebrospinal fluid biomarker analysis was performed to obtain well-characterized groups. EEG spectral features were extracted and the differences between the three groups, as well as correlations with MoCA, were investigated. Results: The results showed significantly lower alpha2 power and alpha2/alpha1 ratio in both AD-MCI and PD-MCI compared to controls. The significantly higher theta and lower beta power and alpha/theta ratio were observed in PD-MCI compared to AD-MCI and HC. MoCA score correlated inversely with theta power and directly with alpha2 and beta powers, as well as with alpha2/alpha1 and alpha/theta ratios. Conclusions: This study highlighted significant differences in EEG patterns in AD-MCI and PD-MCI patients and remarked the role of EEG parameters as possible surrogate markers of cognitive status in both neurodegenerative diseases. Significance: In addition to well-established biomarkers, our findings could support early detection of cognitive dysfunction in neurodegenerative disorders and could help to monitor disease progression and therapeutic responses. (c) 2022 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Automated summary

This study investigated changes in brain cortical activity using high-density EEG in patients with Alzheimer's and Parkinson's diseases who had mild cognitive impairment (MCI), and explored the correlations between quantitative spectral EEG parameters and global cognitive status. The results revealed significant alterations in EEG patterns between AD-MCI and PD-MCI patients, and highlighted the potential of EEG parameters as surrogate markers for cognitive status in both neurodegenerative diseases.