title: Assessment of white matter tract damage in mild cognitive impairment and Alzheimer's disease.
abstract: Diffusion tensor MRI-based tractography was used to investigate white matter (WM) changes in the major limbic (i.e., fornix and cingulum) and cortico-cortical association pathways [i.e., the uncinate fasciculus, the inferior fronto-occipital fasciculus, the inferior longitudinal fasciculus (ILF), the superior longitudinal fasciculus, and the corpus callosum] in 25 Alzheimer's disease (AD) patients, 19 amnestic mild cognitive impairment (aMCI) patients, and 15 healthy controls (HC). Mean diffusivity (MD), fractional anisotropy (FA), as well as axial (DA) and radial (DR) diffusivities were measured for each tract, using an atlas-based tractography approach. The association of WM tract integrity with hippocampal volume was also assessed. MD values were significantly different among groups in all WM tracts (P values ranging from 0.002 to 0.03), except in the fornix (P = 0.06) and the inferior fronto-occipital fasciculus (P = 0.09). Conversely, FA was significantly different among groups in the fornix only (P = 0.02). DA values were significantly different among groups in all WM tracts (P values ranging from 0.001 to 0.01), except in the fornix (P = 0.13) and the cingulum (P = 0.29). Significantly different DR values among groups were found in the fornix (P = 0.02) and the ILF (P = 0.01). In the fornix and cingulum, DR was significantly more increased than DA in both patient groups compared to HC. No difference in DA versus DR was found in cortico-cortical WM tracts. DA values in the fornix were significantly correlated with the hippocampal volume. This study demonstrates a different pattern of WM involvement in the limbic and cortico-cortical association pathways in aMCI and AD patients.
authors.affiliation: Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, Scientific Institute and University Ospedale San Raffaele, Milan, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Pievani
authors.forename: Federica
authors.initials: F
authors.lastname: Agosta
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Pagani
authors.forename: Elisa
authors.initials: E
authors.lastname: Canu
authors.forename: Stefania
authors.initials: S
authors.lastname: Sala
authors.forename: Martina
authors.initials: M
authors.lastname: Absinta
authors.forename: Cristina
authors.initials: C
authors.lastname: Geroldi
authors.forename: Rossana
authors.initials: R
authors.lastname: Ganzola
authors.forename: Giovanni B
authors.initials: GB
authors.lastname: Frisoni
authors.forename: Massimo
authors.initials: M
authors.lastname: Filippi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000473:pathology*; D001921:Brain / Q000473:pathology* / Q000503:physiopathology; D003072:Cognition Disorders / Q000175:diagnosis / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D009434:Neural Pathways / Q000473:pathology / Q000503:physiopathology; D012720:Severity of Illness Index