Affiliations: [a] Department of Radiology, Michigan State University, East Lansing, MI, USA | [b] Department of Psychology, Michigan State University, East Lansing, MI, USA | [c] Cognitive Imaging Research Center, Michigan State University, East Lansing, MI, USA | [d] Department of Neurology, Michigan State University, East Lansing, MI, USA
Correspondence:
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Correspondence to: David C. Zhu, Ph.D., 293 Farm Lane, Room 358, Michigan State University, East Lansing, MI 48824, USA. Tel.: +1 517 353 9432; Fax: +1 517 432 2849; E-mail: zhuda@msu.edu.
Abstract: We applied a multi-modal imaging approach to examine structural and functional alterations in the default-mode network (DMN) that are associated with Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI), a transitional phase between healthy cognitive aging and dementia. Subjects included 10 patients with probable AD, 11 patients with aMCI, and 12 age- and education-matched normal controls (NC). Whole-brain resting-state functional, diffusion-weighted, and volumetric magnetic resonance imaging (MRI) data as well as 18F-fluorodeoxyglucose-based positron emission tomography (FDG-PET) data were acquired. We carried out resting-state functional MRI-based functional connectivity and diffusion MRI-based structural connectivity analyses using isthmus of the cingulate cortex (ICC) and the subjacent white matter as the seeds. Whole-brain group and region of interest-based analyses demonstrated that AD weakens the structural and functional connections between ICC and other regions within the DMN, consistent with regional reduction of metabolic activity and atrophy within the DMN. A progressive weakening trend of these connections was also observed from NC to aMCI and then AD, although significant differences between aMCI and the other two groups were not found. Overall, based on both FDG-PET and MRI results, the DMN appears to serve as a window to understanding structural and functional brain changes associated with AD and aMCI.
