title: Callosal degeneration topographically correlated with cognitive function in amnestic mild cognitive impairment and Alzheimer's disease dementia.
abstract: Degeneration of the corpus callosum (CC) is evident in the pathogenesis of Alzheimer's disease (AD). However, the correlation of microstructural damage in the CC on the cognitive performance of patients with amnestic mild cognitive impairment (aMCI) and AD dementia is undetermined. We enrolled 26 normal controls, 24 patients with AD dementia, and 40 single-domain aMCI patients with at least grade 1 hippocampal atrophy and isolated memory impairment. Diffusion tensor imaging (DTI) with fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (DA), and radial diffusivity (DR) were measured. The entire CC was parcellated based on fiber trajectories to specific cortical Brodmann areas using a probabilistic tractography method. The relationship between the DTI measures in the subregions of the CC and cognitive performance was examined. Although the callosal degeneration in the patients with aMCI was less extended than in the patients with AD dementia, degeneration was already exhibited in several subregions of the CC at the aMCI stage. Scores of various neuropsychological tests were correlated to the severity of microstructural changes in the subregional CC connecting to functionally corresponding cortical regions. Our results confirm that CC degeneration is noticeable as early as the aMCI stage of AD and the disconnection of the CC subregional fibers to the corresponding Brodmann areas has an apparent impact on the related cognitive performance.
authors.affiliation: Department of Neurology, National Yang-Ming University, School of Medicine, Taipei, Taiwan; Department of Neurology, Taipei Veterans General Hospital, Taipei, Taiwan; Brain Research Center, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Pei-Ning
authors.initials: PN
authors.lastname: Wang
authors.forename: Kun-Hsien
authors.initials: KH
authors.lastname: Chou
authors.forename: Ni-Jung
authors.initials: NJ
authors.lastname: Chang
authors.forename: Ker-Neng
authors.initials: KN
authors.lastname: Lin
authors.forename: Wei-Ta
authors.initials: WT
authors.lastname: Chen
authors.forename: Gong-Yau
authors.initials: GY
authors.lastname: Lan
authors.forename: Ching-Po
authors.initials: CP
authors.lastname: Lin
authors.forename: Jiing-Feng
authors.initials: JF
authors.lastname: Lirng
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000150:complications / Q000473:pathology* / Q000523:psychology; D000647:Amnesia / Q000209:etiology / Q000473:pathology* / Q000523:psychology; D016880:Anisotropy; D001284:Atrophy / Q000473:pathology; D001921:Brain / Q000473:pathology; D003071:Cognition; D060825:Cognitive Dysfunction / Q000150:complications / Q000473:pathology* / Q000523:psychology; D003337:Corpus Callosum / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D005260:Female; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D009410:Nerve Degeneration / Q000209:etiology / Q000473:pathology / Q000523:psychology; D009483:Neuropsychological Tests; D009929:Organ Size; D011569:Psychiatric Status Rating Scales
keywords: Brodmann area; corpus callosum; diffusion tensor imaging; neuroimaging; probabilistic tractography