CHARACTERIZING FUNCTIONAL EXCITATION/INHIBITION IN SUCCESSFUL COGNITIVE AGING, ESTIMATED USING ELECTROENCEPHALOGRAPHY

Successful cognitive aging (SCA) is characterized by the preservation of cognitive performance despite typical structural changes related to aging. Electrophysiology allows the study of functional mechanisms underlying these exceptionally positive aging trajectories. Electroencephalography (EEG) can be used to estimate cortical excitation-inhibition balance (EI), a relevant marker related to neuronal efficiency. Changes in EI have been associated with cognitive decline in normative aging, as well as in mild cognitive impairment (MCI) and Alzheimer’s disease. Although the preservation of this balance may well be a protective factor for cognitive performance in SCA, EI has hardly been explored in very old individuals. The aim of this study is to characterize functional excitation-inhibition (fEI) estimated using EEG in very old adults with SCA, in comparison to adults with MCI. Thirty individuals, divided into two groups (SCA and MCI, 85 ± 2 years, balanced in age and sex), underwent EEG recordings (5 minutes of eyes-closed and eyes-open resting state), and a comprehensive neuropsychological assessment. Estimated fEI values were compared between groups and correlated with age and cognitive performance. Values of fEI were not significantly different between SCA and MCI and did not correlate with age. However, higher mean fEI values correlated negatively with cognitive performance in both SCA and MCI, indicating that increased excitability was associated with cognitive decline. These findings, in line with previous literature, motivate further investigation into the electrophysiological bases of cognitive preservation in successful cognitive aging and support the use of EI balance as a biomarker of brain health.