Reduced integration and improved segregation of functional brain networks in Alzheimer's disease

TL;DR

This study investigates how Alzheimer's disease affects brain network organization, revealing reduced global integration and increased local segregation in EEG-based functional networks, which correlate with cognitive decline.

Contribution

It provides novel insights into the dynamic topological changes in AD brain networks using EEG source connectivity and graph analysis.

Findings

AD networks show lower global integration compared to controls.

AD networks exhibit higher local segregation.

Alterations in network topology correlate with cognitive scores.

Abstract

Emerging evidence shows that cognitive deficits in Alzheimer disease (AD) are associated with disruptions in brain functional connectivity. Thus, the identification of alterations in AD functional networks has become a topic of increasing interest. However, to what extent AD induces disruption of the balance of local and global information processing in the human brain remains elusive. The main objective of this study is to explore the dynamic topological changes of AD networks in terms of brain network segregation and integration. We used electroencephalography (EEG) data recorded from 20 participants (10 AD patients and 10 healthy controls) during resting state. Functional brain networks were reconstructed using EEG source connectivity computed in different frequency bands. Graph theoretical analyses were performed assess differences between both groups. Results revealed that AD networks, compared to networks of age matched healthy controls, are characterized by lower global information processing (integration) and higher local information processing (segregation). Results showed also significant correlation between the alterations in the AD patients functional brain networks and their cognitive scores. These findings may contribute to the development of EEG network-based test that could strengthen results obtained from currently used neurophysiological tests in neurodegenerative diseases.