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IC–P–005: White matter changes associated with dementia development in patients with subcortical ischemic white matter lesions: A diffusion tensor image study
Author(s) -
Yang Dong Won,
Kim Beum Saeng,
Shon Young Min,
Shim Yong Soo,
Cho Hyun,
Yoon Bora,
Ahn Kook-Jin
Publication year - 2006
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2006.05.2210
Subject(s) - white matter , fractional anisotropy , internal capsule , leukoaraiosis , corpus callosum , diffusion mri , medicine , dementia , superior longitudinal fasciculus , fasciculus , vascular dementia , cardiology , hyperintensity , pathology , radiology , magnetic resonance imaging , disease
observations, the present study characterized default mode activity using analysis of low frequency functional correlations between brain regions (Biswal et al., 1995 MRM; Fox et al., 2005 PNAS). BOLD-contrast fMRI imaging was used and the correlation coefficient between regions was the dependent measure. Methods: Functional correlations were explored in a large sample of 38 young adults (age 22.4 y; 18 M), 55 nondemented older adults (76.5 y; 18 M) and 17 older adults (76.9 y; 12 M) with a clinical diagnosis of AD in accordance with validated criteria using standard assessment protocols for both clinical and neuropsychological measures. Data were from Lustig et al. (2003 PNAS). To minimize anatomical biases, seed regions used for correlation analyses were defined in a separate data set of an equal number of young, nondemented older, and AD participants (n 24 total). Many participants also underwent diffusion tensor imaging (DTI) at nearby times to assess white matter integrity. Conclusions: Results revealed that functional correlations were dramatically reduced between anterior and posterior regions comprising the default mode in nondemented older adults compared to the young. Considerably more modest reductions in correlations were noted between the nondemented and AD older adult groups. We also examined relationships between functional correlation measures, performance on neuropsychological tests, and DTI in the same group of individuals, as they are useful to understand the interaction between potentially related changes in aging. Our results are consistent with the hypothesis that aging is associated with disconnection of distributed brain networks that show coordinated activity in young adults. Future analyses will explore whether our observed functional disconnection in aging is related to findings of white-matter degradation (e.g., O’Sullivan et al., 2000 Neurology; Head et al., 2004 CC) and also whether functional disconnection is prominent in nondemented aging in the absence of AD.