Subtle alterations in cerebrovascular reactivity in mild cognitive impairment detected by graph theoretical analysis and not by the standard approach

Abstract

There is growing support that cerebrovascular reactivity (CVR) in response to a vasodilatory challenge, also defined as the cerebrovascular reserve, is reduced in Alzheimer's disease dementia. However, this is less clear in patients with mild cognitive impairment (MCI). The current standard analysis may not reflect subtle abnormalities in CVR. In this study, we aimed to investigate vasodilatory-induced changes in the topology of the cerebral blood flow correlation (CBFcorr) network to study possible network-related CVR abnormalities in MCI. For this purpose, four CBFcorr networks were constructed: two using CBF SPECT data at baseline and under the vasodilatory challenge of acetazolamide (ACZ), obtained from a group of 26 MCI patients; and two equivalent networks from a group of 26 matched cognitively normal controls. The mean strength of association (SA) and clustering coefficient (C) were used to evaluate ACZ-induced changes on the topology of CBFcorr networks. We found that cognitively normal adults and MCI patients show different patterns of C and SA changes. The observed differences included the medial prefrontal cortices and inferior parietal lobe, which represent areas involved in MCI's cognitive dysfunction. In contrast, no substantial differences were detected by standard CVR analysis. These results suggest that graph theoretical analysis of ACZ-induced changes in the topology of the CBFcorr networks allows the identification of subtle network-related CVR alterations in MCI, which couldn't be detected by the standard approach.

Networks of myelin covariance

“…It is this approach that allows the estimation of the interactions between structures by the Pearson correlation coefficients. It has been proven that such type of analysis reveals hidden organizational properties of brain anatomy that are difficult to detect through classical univariate approaches (Bassett et al, ; Li, Bin, Hong, & Gao, ; Melie‐García et al, ; Sánchez‐Catasús et al, ; Yu et al, ; Zalesky, Fornito, Egan, Pantelis, & Bullmore, ).…”

“…Panel (c) represents the trajectories of the relative size of the largest components as the principal nodes are "deleted" ("attacked") for the sparsity degree highlighted in panel a (green box) [Color figure can be viewed at wileyonlinelibrary.com] MELIE-GARCIA ET AL. | 15452012;Li, Bin, Hong, & Gao, 2010;Melie-García et al, 2013;S anchez- Catas us et al, 2017;Yu et al, 2013;Zalesky, Fornito, Egan, Pantelis, & Bullmore, 2012).…”

Age‐related changes in cerebrovascular health and their effects on neural function and cognition: A comprehensive review

“…In mice, age‐dependent impairment of neurovascular coupling in the hippocampus correlated with reduced performance on a spatial memory task (Lourenço et al., 2018). There is also a wealth of research relating CVR impairment to age‐related cerebral pathologies, including mild cognitive impairment and Alzheimer's Disease (Alwatban et al., 2019; Bär et al., 2007; Cantin et al., 2011; Chen, 2018; Glodzik et al., 2013; Gongora‐Rivera et al., 2018; Heun et al., 1994; Kalaria, 2010; Kelleher & Soiza, 2013; Richiardi et al., 2015; Sánchez‐Catasús et al., 2017; Silvestrini et al., 2006; Viticchi et al., 2012; Yezhuvath et al., 2012). Overall, this research suggests that age‐related declines in CVR are mostly present in the temporal lobe, although future work will help to confirm and clarify the details of the effects of age on regional CVR and cognition.…”

Feasibility of pharmacokinetic parametric PET images in scaled subprofile modelling using principal component analysis

“…While these methods are useful to identify differences between groups, they might not have sufficient power to explore some of the subtle brain alterations that frequently occur in neurological disorders ( Alexander and Moeller, 1994 ). Therefore, other multivariate approaches for analysis of functional brain images are gaining interest, such as graph theory ( Bullmore and Sporns, 2009 , Sánchez-Catasús et al, 2017 ), dynamic causal modelling ( Friston et al, 2003 ), scaled subprofile model ( Meles et al, 2015 , Peng et al, 2014 , Spetsieris et al, 2009 ), and independent component analysis (ICA) ( Pagani et al, 2017 ).…”