DINÂMICA TEMPORAL DE REDES FUNCIONAIS CORTICAIS EM PORTADORES DE ALZHEIMER

Resumen

Alzheimer’s Disease (AD) is the main form of dementia among the elderly and a major public health issue. Its neuropathological hallmarks are neurofibrillary tangles and amyloid deposition, which results in the loss of functional connectivity at pre-clinical stages. This study aims to compare spatial and temporal topological patterns of cortical brain functional connectivity between healthy individuals and patients with AD at different stages (very mild, mild or moderate to severe). The EEG data (19 electrodes, 10-20 system) was obtained from patients at Taipei Veterans General Hospital, Taiwan. Functional cerebral networks (FCN) were built by the Motif Synchronization method and then characterized by indices of temporal connectivity and stability. Synchronicity and network topology of FCN were also evaluated. We evaluated connectivity as the average weighted degree and found that it follows a trend, in which connectivity decreases over disease progression. We evaluated topological stability as the vertices variation coefficient (VVC) and found that it also follows a trend, in which stability increases with disease progression. The analysis of the most representative hubs revealed there is a decreased proportion of hubs in brain regions markedly affected by AD. This decrease is more accentuated in later than earlier disease stages, in accordance with previous studies. These data indicate altered connectivity pattern and stability in dynamics of the functional synchronization networks from the analysed groups. Due to high individual variability, which could have masked statistical significance in our data, we suggest future studies with longitudinal design to address the questions presented in this paper.