title: Communication of brain network core connections altered in behavioral variant frontotemporal dementia but possibly preserved in early-onset Alzheimer's disease.
abstract: 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 ashubs, 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 the brain's communication network are globally and regionally altered in bvFTD, compared to healthy participants; however, the overall organization of the high-cost and high-capacity networks were relatively preserved in EOAD participants, relative to controls. Disruption of the major central hubs that transfer information between brain regions may impair neural communication and functional integrity in characteristic ways typical of each subtype of dementia.
authors.affiliation: Imaging Genetics Center, Institute for Neuroimaging & Informatics, University of Southern California, Los Angeles, CA, USA.
authors.forename: Madelaine
authors.initials: M
authors.lastname: Daianu
authors.affiliation: Imaging Genetics Center, Institute for Neuroimaging & Informatics, University of Southern California, Los Angeles, CA, USA.
authors.forename: Neda
authors.initials: N
authors.lastname: Jahanshad
authors.affiliation: Alzheimer's Disease Research Center, Dept. of Neurology, UCLA School of Medicine, Los Angeles, CA, USA.
authors.forename: Mario F
authors.initials: MF
authors.lastname: Mendez
authors.affiliation: Dept. of Psychiatry, Semel Institute, UCLA School of Medicine, Los Angeles, CA, USA.
authors.forename: George
authors.initials: G
authors.lastname: Bartzokis
authors.affiliation: Alzheimer's Disease Research Center, Dept. of Neurology, UCLA School of Medicine, Los Angeles, CA, USA.
authors.forename: Elvira E
authors.initials: EE
authors.lastname: Jimenez
authors.affiliation: Imaging Genetics Center, Institute for Neuroimaging & Informatics, University of Southern California, Los Angeles, CA, USA.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Thompson
keywords: Alzheimer’s disease; communication cost; frontotemporal dementia; graph theory; hub; structural network
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