Decreased between‐hemisphere connectivity strength and network efficiency in geriatric depression

Abstract

White matter (WM) lesions have been recognized as a key etiological factor in geriatric depression. However, little is known about the topological pattern changes of WM in geriatric depression in the remitted state (RGD) and its relationship to depressive episodes. To address these questions, we acquired diffusion tensor images in 24 RGD and 24 healthy participants. Among them, 10 patients and 19 healthy controls completed a 1-year follow up. Between-hemisphere connectivity and graph theoretical methods were used to analyze the data. We found significantly reduced WM connectivity between the left and right hemisphere in the RGD group compared with the control group. Those with multiple depression episodes had greater reduction in between-hemisphere connectivity strength than those with fewer episodes. In addition, the RGD group had a reduced global clustering coefficient, global efficiency, and network strength, and an increased shortest path length compared with the controls. A lower clustering coefficient was correlated with poorer memory function. The reduction of nodal clustering coefficient, global efficiency, and network strength in several regions were associated with slower information processing speed. At 1-year follow up, the network properties in the RGD subjects were significantly changed suggesting instability of WM network properties of depressed patients. Together, our study provides direct evidence of reduced between-hemisphere WM connectivity with greater depressive episodes, and of alterations of network properties with cognitive dysfunction in geriatric depression.

Weight Rich-Club Analysis in the White Matter Network of Late-Life Depression with Memory Deficits

“…In the present study, our findings in the white matter network change in LLD patients with or without memory deficits demonstrate that (1) impaired rich-club organization, rich-club connective average strength and assortativity was found in 39 LLD patients compared to 30 HC subjects; (2) compared to LLD-IM patients, LLD-MD patients had disruptive feeder and local connections, especially in cognitive control network (CCN) and corticostriatal circuits; and (3) the alterations of global network properties were accompanied by slight cognitive function change, such as processing speed and memory in the current study. Our findings were compatible with the previous study in the white matter network topological features of LLD patients (Bai et al, 2012 ; Li et al, 2017 ) to some extent, and extend our understanding in the pathological progression of LLD by describing the rich-club properties of LLD-MD patients.…”

“…This technology has been applied to discover the underlying brain structural changes under neuropsychological diseases (Daianu et al, 2015 ; Gong and He, 2015 ; Schmidt et al, 2017 ). In LLD, the breakdown of global network properties and reductive connectivity between-hemisphere was found in previous studies of the white matter connective network (Bai et al, 2012 ; Li et al, 2017 ). But, there is still largely unknown about the topological organization, especially the role of hub, in LLD.…”

“…To determine the significant differences in the subnetwork connection between the LLD-MD and LLD-IM groups. NBS was taken and the procedure developed by Zalesky and Li was used (Zalesky et al, 2010 ; Li et al, 2017 ). First, the t -test statistic threshold was chosen by primary threshold ( P < 0.01).…”

Evidence for Structural and Functional Alterations of Frontal-Executive and Corticolimbic Circuits in Late-Life Depression and Relationship to Mild Cognitive Impairment and Dementia: A Systematic Review

“…Furthermore, LLD compared to HC groups have shown to have impairment in executive function, but no difference in verbal and visuospatial memory (Dybedal et al, 2013), or impairment in attention, and memory functions, but no difference in total cognitive function, processing speed, and executive function (Yue et al, 2015). Other studies have found no differences in the cognitive profile of LLD and HC groups (Alexopoulos et al, 2012), at baseline or over 1 year follow up (Li X. et al, 2017). The discrepancies may be due to differences in the cognitive tests that were used in these studies.…”

“…Four DWI studies used network analysis (Li X. et al, 2017;Mai et al, 2017) and graph theory analysis methods (Bai a studies that had reported findings in both rs-fMRI and DWI. b DWI findings were reported in two separate publications.…”