Year: 2013
Type: article
Study design: Observational Study
Abstract: Much is known about regional brain atrophy in Alzheimer's disease (AD), yet our knowledge about the network nature of AD-associated Aβ accumulation is limited. In this study, we hypothesized that PIB binding during individual PET imaging acquisitions may hold information about temporo-spatial relationships between cerebral regions. We think that significant association between amyloid accumulations of distributed regions may point out to underlying temporal relationships. For instance, specific regions may predict the amyloid deposits of other regions in the brain. The aim of this study was to describe the amyloid hubs that are either affecting or being affected by other amyloid regions of the brain at the individual level. We used PIB-PET images from a cognitive normal sample of elderly controls (N=159; age=74.27) and a Granger causality strategy to study the forecasting properties of the PIB dynamical signal during individual acquisitions (Fig. 1-A). Granger causality test is used here for statistically determining whether time series of PIB signal in brain voxels are valuable in forecasting another PIB time series of the brain. Different lags were used in order to optimize the approach. For each subject, we computed two connectivity matrices: 1) one that includes all the Granger out-going associations and 2) another that includes all the Granger in-coming associations between voxels. Finally, we computed the degree of connectivity of each voxel in the brain by summing the out-going or in-coming associations. We identified regions that accumulate a high number of associations in both, Granger out-going and Granger in-coming relationships. Amyloid hubs that influence the uptake of other regions were particularly located in the temporo-parietal and PCC/precuneus regions (out-going); while amyloid hubs that are being influenced by a high amount of regions across the brain were located in the lateral and medial frontal regions (in-coming) (see an example of an individual subject in Fig. 1-B and 1-C). Although these findings are promising to understand the dynamical binding of PIB and network activity of the amyloid pathology in preclinical stages of AD, further work is needed in order to clarify the specific meaning of the temporo-spatial relationships between amyloid hubs.
Source: Alzheimer s & Dementia
Language: English
Subfield: Psychiatry and Mental health
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2084696461