Memory Encoding Relation with Alzheimer's Severity: Excitation-to-Inhibition Insights

Alzheimer's disease (AD) is characterized by progressive cognitive decline, with memory problems being a major symptom. To improve AD diagnosis, this study explores a novel approach using electroencephalography (EEG) during the encoding stage of working memory. It focuses on the excitation-to-inhibition (E/I) imbalance and detrended fluctuation analysis (DFA) as potential markers for AD detection. AD involves tau-mediated neuronal inhibition, impacting brain activity during cognitive tasks. Cognitive decline in AD is linked to pathological changes reflected in the E/I balance. EEG captures brain activity during memory encoding, potentially revealing AD-specific patterns. Previous studies have explored brain activity alterations in AD during encoding, this study goes further by investigating the complexity of electrical activity using DFA and reflecting the neural state utilizing E/I. EEG data is collected from AD, mild cognitive impairment (MCI), and healthy control (HC) groups while performing a working memory task. The encoding stage data for each group is analyzed using DFA and E/I measures at different frequency bands. The increased long-range temporal correlation in AD compared to MCI and HC suggests altered temporal dynamics in AD during encoding. The lower E/I values in AD, followed by MCI and HC, indicate reduced neural activity during encoding with increasing AD severity. This preliminary study suggests that the EEG-based E/I measure and DFA analysis during working memory encoding show potential for distinguishing AD, MCI, and HC subjects. This approach provides valuable insights for potential AD prediction and stage discrimination by capturing altered neural activity and complex brain dynamics.