Minimum Spanning Tree Reflects the Alterations of the Default Mode Network During Alzheimer’s Disease

Abstract

This study analyzes the connectivity pattern of the default mode network (DMN) in patients with Alzheimer's disease (AD) in comparison with young and elderly controls using the minimum spanning tree (MST). This tree is a tool from graph theory and connects all the nodes of a graph with the minimum cost. The findings revealed that the alterations of the basic structure represented by the MST might provide valuable insights about the physiopathology of the disease. Additionally, by making use of the MST for functionally clustering the DMN, it was shown that the functional subnetworks comprising the DMN differed among the three subject groups. Nonetheless, there were intact prefrontal and temporal networks in elderly controls and AD patients, as well. The analysis shows that although the topologies of the MST characterized by the degree distributions do not differ significantly among the groups, the DMN of the AD patients exhibits a higher segregation, insomuch that posterior cingulate/precuneus and hippocampus/parahippocampus are heavily isolated from rest of the network. We conclude that the MST can be used effectively for analyzing cortical networks.

A Resting-State Brain Functional Network Study in MDD Based on Minimum Spanning Tree Analysis and the Hierarchical Clustering

“…And the hierarchical clustering in combination with the MST has been used in different cognitive domains. Hierarchical clustering analysis of the MST showed that the connections between the parahippocampal gyrus and posterior cingulate gyrus were disrupted in Alzheimer patients [42]. Impaired communication between functional clusters in AD was found in one MEG study [46].…”

“…In a study of Multiple Sclerosis, findings indicate that MST network analyses were able to detect network changes in the Multiple Sclerosis (MS) patients [41]. In the study of Alzheimer's disease, MST was regarded as an effective method for analyzing cortical networks [42].…”

The trees and the forest: Characterization of complex brain networks with minimum spanning trees

“…The first fMRI study that analysed the MST itself was performed on a data set set (#2-2000-1118W) from an international repository of raw fMRI data (www.fmridc.org) (Ciftçi, 2011). This data set consists of fMRI recordings in 14 healthy young subjects, 14 healthy elderly controls and 13 patients with "clinical dementia" during a simple sensory motor task.…”

“…Hierarchical clustering analysis of the MST showed that the connection between the hippocampus/parahippocampal gyrus on the one hand to the precuneus and posterior cingulate gyrus on the other hand, that is normally mediated by the angular gyrus and the inferior temporal gyrus, was disrupted in Alzheimer patients. Ciftçi (2011) concluded that the MST carries information about the clustering of the network.…”

“…The MST also provides a good starting point for hierarchical clustering of complex networks. This approach has already been proven useful for distinguishing between sub groups of epilepsy patients and identification of disconnected clusters in Alzheimer's disease (Ciftçi, 2011;Lee et al, 2006). A more systematic use of hierarchical clustering in combination with the MST could show whether clusters identified in this way correspond to different cognitive domains.…”