tags: aging; functional connectivity; fMRI; master's; dissertation; cortical thickness; fALFF; cortical atrophy; atrophy

Evidence of regional associations between age-related inter-individual differences in resting-state functional connectivity and cortical thinning revealed through a multi-level analysis

B.H. Vieira, C. Rondinoni, C.E.G. Salmon, NeuroImage, 2020-05-01
Open Access 10.1016/j.neuroimage.2020.116662

This paper stems from my Master's dissertation[1], completed in 2018. The main motivator for this paper (and the dissertation as well) was the fact that the macroscopical effects of aging on the brain are well understood, but the relationships between several such phenomena are yet unclear.

We set to study two well described effects of aging on the brain: generalized cortical atrophy and differences in resting-state functional connectivity (RSFC). We reproduced the main results from the literature and, with that, we tried to find ways that both processes overlap.

The main finding is towards the fact that there are correlations between thickness atrophy and RSFC alterations, but these do not appear in all regions. Some regions tend to become more connected to regions undergoing increased atrophy and less connected to regions that experience less atrophy, while some other regions do the opposite, and become more connected with regions that show less atrophy.

We also provide interpretations of these effects under current neuroscientific theories of brain aging.

Abstract

Normal aging incurs functional and anatomical alterations in the brain. Cortical thinning, age-related alterations in resting-state functional connectivity (RSFC) and reductions in fractional amplitude of low frequency fluctuations (fALFF) are key components of brain aging that can be studied by neuroimaging. However, the level of association between these processes has not been fully established. We performed an analysis at multiple-levels, i.e. region or connection and modality, to investigate whether the evidence for the effect of aging on fALFF, RSFC and cortical thickness are associated in a large cohort. Our results show that there is a positive association between the level of evidence of age-related effects in all three in the brain. We also demonstrate that on a regional basis the association between RSFC alterations and cortical atrophy may be either positive or negative, which may relate to compensatory mechanisms predicted by the Scaffolding Theory of Aging and Cognition (STAC).

[1] Brain functional connectivity in regions with cortical thinning linked to healthy aging (Dissertation), University of São Paulo, 2018-02-22