title: Patterns of age-related water diffusion changes in human brain by concordance and discordance analysis.
abstract: In diffusion tensor imaging (DTI), interpreting changes in terms of fractional anisotropy (FA) and mean diffusivity or axial (D(||)) and radial (D(⊥)) diffusivity can be ambiguous. The main objective of this study was to gain insight into the heterogeneity of age-related diffusion changes in human brain white matter by analyzing relationships between the diffusion measures in terms of concordance and discordance instead of evaluating them separately, which is difficult to interpret. Fifty-one cognitively normal subjects (22-79 years old) were studied with DTI at 4 Tesla. Age was associated with widespread concordant changes of decreased FA and increased MD but in some regions significant FA reductions occurred discordant to MD changes. Prominent age-related FA reductions were primarily related to greater radial (D(⊥)) than axial (D(||)) diffusivity changes, potentially reflecting processes of demyelination. In conclusion, concordant/discordant changes of DTI indices provide additional characterization of white matter alterations that accompany normal aging.
authors.affiliation: Center for Imaging of Neurodegenerative Diseases, VA Medical Center, San Francisco, CA, United States. Yu.Zhang@ucsf.edu
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: An-Tao
authors.initials: AT
authors.lastname: Du
authors.forename: Satoru
authors.initials: S
authors.lastname: Hayasaka
authors.forename: Geon-Ho
authors.initials: GH
authors.lastname: Jahng
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hlavin
authors.forename: Wang
authors.initials: W
authors.lastname: Zhan
authors.forename: Michael W
authors.initials: MW
authors.lastname: Weiner
authors.forename: Norbert
authors.initials: N
authors.lastname: Schuff
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism* / Q000502:physiology; D016880:Anisotropy; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012016:Reference Values; D018709:Statistics, Nonparametric; D014867:Water / Q000378:metabolism*; D055815:Young Adult
chemical_list: D014867:Water