Distinct neurodynamics of functional brain networks in Alzheimer's disease and frontotemporal dementia as revealed by EEG

Objective While Alzheimer's disease (AD) and frontotemporal dementia (FTD) show some common memory deficits, these two disorders show partially overlapping complex spatiotemporal patterns of neural dynamics. The objective of this study is to characterize these patterns to better understand the general principles of neurodynamics in these conditions. Methods A comprehensive array of methods to study brain rhythms and functional brain networks are used in the study, from spectral power measures to Lyapunov exponent, phase synchronization, temporal synchrony patterns, and measures of the functional brain connectivity. Furthermore, machine learning techniques for classification are used to augment the methodology. Results Multiple measures (spectral, synchrony, functional network organization) indicate an array of differences between neurodynamics between AD and FTD, and control subjects across different frequency bands. Conclusions These differences taken together in an integrative way suggest that AD neural activity may be less coordinated and less connected across areas, and more random, while FTD shows more coordinated neural activity (except slow frontal activity). Significance AD and FTD may represent opposite changes from normal brain function in terms of the spatiotemporal coordination of neural activity. Deviations from normal in both directions may lead to neurological deficits, which are specific to each of the disorders.