Communication of brain network core connections altered in behavioralvariant frontotemporal dementia but possibly preserved in early-onsetAlzheimer’s disease

摘要

Diffusion imaging and brain connectivity analyses can assess white matter deterioration in the brain, revealing the underlying patterns of how brain structure declines. Fiber tractography methods can infer neural pathways and connectivity patterns, yielding sensitive mathematical metrics of network integrity. Here, we analyzed 1.5-Tesla whole-brain diffusion-weighted images from 64 participants – 15 patients with behavioral variant frontotemporal dementia (bvFTD), 19 with early-onset Alzheimer’s disease (EOAD), and 30 healthy elderly controls. Using whole-brain tractography, we reconstructed structural brain connectivity networks to map connections between cortical regions. We evaluated the brain’s networks focusing on the most highly central and connected regions, also known as hubs, in each diagnostic group – specifically the “high-cost” structural backbone used in global and regional communication. The high-cost backbone of the brain, predicted by fiber density and minimally short pathways between brain regions, accounted for 81–92% of the overall brain communication metric in all diagnostic groups. Furthermore, we found that the set of pathways interconnecting high-cost and high-capacity regions of thebrain’s communication network are globally and regionally altered inbvFTD, compared to healthy participants; however, the overall organization ofthe high-cost and high-capacity networks were relatively preserved in EOADparticipants, relative to controls. Disruption of the major central hubs thattransfer information between brain regions may impair neural communication andfunctional integrity in characteristic ways typical of each subtype ofdementia.