The following is the summary of “Disrupted topological organization of functional brain networks in Alzheimer’s disease patients with depressive symptoms” published in the December 2022 issue of Psychiatry by Guo, et al.

Alzheimer’s disease (AD) is characterized by a number of symptoms, one of which is depression, but its brain mechanism is not well understood. The goal of this study was to use graph theory analysis to delve into the topological characteristics of AD patients who also experienced depressive symptoms (D-AD). About 24 depressed Alzheimer’s disease (D-AD) patients, 20 non-depressed Alzheimer’s disease (nD-AD), and twenty healthy controls all had 3-Tesla rsfMRI. Using a graph theoretic approach, researchers were able to locate networks in a quiescent condition.

The topological metrics were evaluated using an ANOVA followed by a post hoc two-sample t-test in GRETNA. Their findings suggest that all 3 communities behave like a small-world network. Comparing normal controls (NCs) to those with D-AD or nD-AD, the former group demonstrated much higher global and local efficiency. Compared with nD-AD patients, D-AD patients demonstrated lower nodal centrality in the pallidum, putamen, and right superior temporal gyrus. Increased nodal centrality was also found in the right superior parietal gyrus, right superior frontal orbital region, and right superior frontal gyrus. 

Nodal betweenness was reduced in the right superior temporal gyrus and elevated in the medial orbital region of the right superior frontal gyrus in those with NC, as compared to nD-AD patients. As shown below, D-AD is linked to changes in topological structure. Their research sheds light on the neural pathways that contribute to D-AD.