Aberrant functional organization within and between resting-state networks in AD

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Neurology

Background:

• Altered functional characteristics are observed in amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD).
• Comprehensive analyses of resting-state networks (RSNs) in aMCI/AD are limited.

Purpose of the Study:

• To investigate functional and structural changes within and between RSNs in aMCI/AD patients.
• To combine multiple imaging modalities for a comprehensive analysis.

Main Methods:

• Identified eight RSNs from functional MRI data using independent component analysis.
• Compared functional connectivity (FC), grey matter volume, and amplitude of low-frequency fluctuations within RSNs.
• Assessed inter-network connectivity between RSNs.

Main Results:

• Decreased FC was found in cognitive-related RSNs in AD, including the precuneus, posterior cingulate cortex, and left superior parietal lobule.
• Reduced grey matter volume and low-frequency fluctuations were observed in AD.
• Decreased inter-network connectivity was noted between the visual network and the left frontoparietal network (LFP), and between anterior and posterior default mode networks (DMNs).
• aMCI patients showed intermediate values between controls and AD patients.

Conclusions:

• Brain networks supporting complex cognitive processes are specifically and progressively impaired in AD.
• Functional connectivity impairments occur both within and between RSNs in AD.
• These findings highlight the progressive nature of network dysfunction in Alzheimer's disease.