Spectral power ratio as a measure of the EEG spectral power shift in mild cognitive impairment due to Alzheimer’s disease

Abstract

AbstractBackgroundMarkers sensitive to brain changes at the transition from mild cognitive impairment (MCI) to dementia due to Alzheimer’s disease (AD) are needed for aiding prognosis and the selection of potential responders to novel interventional therapies. EEG markers may be advantageous due to their accessibility.Prior research suggests that AD is associated with a shift in the brain’s oscillatory activity from higher to lower frequencies which can be captured as changes in the EEG spectral power ratio (SPR: α + β /δ + θ), a measurement associated with executive function1. The aim of the present study is to extend these findings to the prodromal stage of AD, and test the association of the SPR with amyloid burden.MethodData was obtained from 31 participants, including 23 aMCI (17 amyloid positive: Aβ+aMCI) and 14 CU individuals. We compared the SPRs between Aβ+aMCI and CU individuals, and tested its correlation with composite scores of executive functions, learning and memory, dementia severity, as well as amyloid load in the Aβ+aMCI group. Test‐retest reliability of the SPR was also inspected and the SPR of MCI individuals with different amyloid status was explored in hypothesis generating analyses.ResultThe SPR was significantly lower in the Aβ+aMCI group compared to the CU group (p = 0.0271) and was significantly correlated with Executive Function scores (r = 0.5634). The SPR showed excellent test‐retest reliability (rAβ+aMCI = 0.8629 and rCU = 0.9786). Logistic regression suggested that aMCI participants with a lower SPR had an increased probability of a positive amyloid PET.ConclusionOur results extended previous findings in AD and suggested that the SPR may be sensitive to pathophysiological changes in aMCI individuals in a cognitively meaningful manner. Further research may confirm these findings and may explore the potential of this measure to aid in the classification of aMCI individuals according to their amyloid status.1. Benwell CSY, Davila‐Pérez P, Fried PJ, Jones RN, Travison TG, Santarnecchi E, Pascual‐Leone A, Shafi MM (2020) EEG spectral power abnormalities and their relationship with cognitive dysfunction in patients with Alzheimer’s disease and type 2 diabetes. Neurobiol Aging 85, 83‐95.