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Updated: Jun 30, 2025

Application of Granger Causality Analysis of the Directed Functional Connection in Alzheimer's Disease and Mild Cognitive Impairment
Published on: August 7, 2017
Shared and differing functional connectivity abnormalities of the default mode network in mild cognitive impairment
Yaxuan Wang1, Qian Li1, Li Yao1
1Department of Radiology and Huaxi MR Research Center (HMRRC), Functional and Molecular lmaging Key Laboratory of Sichuan Province, West China Hospital, Sichuan University, No. 37 Guo Xue Alley, Wuhou District, Chengdu 610041, Sichuan Province, P.R. China.
Abstract:
Alzheimer's disease (AD) and mild cognitive impairment (MCI) both show abnormal resting-state functional connectivity (rsFC) of default mode network (DMN), but it is unclear to what extent these abnormalities are shared. Therefore, we performed a comprehensive meta-analysis, including 31 MCI studies and 20 AD studies. MCI patients, compared to controls, showed decreased within-DMN rsFC in bilateral medial prefrontal cortex/anterior cingulate cortex (mPFC/ACC), precuneus/posterior cingulate cortex (PCC), right temporal lobes, and left angular gyrus and increased rsFC between DMN and left inferior temporal gyrus. AD patients, compared to controls, showed decreased rsFC within DMN in bilateral mPFC/ACC and precuneus/PCC and between DMN and left inferior occipital gyrus and increased rsFC between DMN and right dorsolateral prefrontal cortex. Conjunction analysis showed shared decreased rsFC in mPFC/ACC and precuneus/PCC. Compared to MCI, AD had decreased rsFC in left precuneus/PCC and between DMN and left inferior occipital gyrus and increased rsFC in right temporal lobes. MCI and AD share a decreased within-DMN rsFC likely underpinning episodic memory deficits and neuropsychiatric symptoms, but differ in DMN rsFC alterations likely related to impairments in other cognitive domains such as language, vision, and execution. This may throw light on neuropathological mechanisms in these two stages of dementia.
Insights
Alzheimer's disease (AD) and mild cognitive impairment (MCI) share decreased default mode network (DMN) functional connectivity, impacting memory. However, distinct DMN alterations in AD suggest broader cognitive deficits.
Area of Science:
- Neuroscience
- Cognitive Neurology
- Medical Imaging
Background:
- Alzheimer's disease (AD) and mild cognitive impairment (MCI) exhibit altered default mode network (DMN) resting-state functional connectivity (rsFC).
- The extent of shared DMN rsFC abnormalities between MCI and AD remains unclear.
Conclusions:
- Shared decreased within-DMN rsFC in MCI and AD may underlie episodic memory deficits and neuropsychiatric symptoms.
- Distinct DMN rsFC alterations in AD suggest potential differences in language, vision, and executive function impairments.
- Findings offer insights into the neuropathological mechanisms differentiating MCI and AD stages.
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