Short- and Long-Term Functional Connectivity Differences Associated with Alzheimer's Disease Progression

Area of Science:

• Neuroscience
• Medical Imaging
• Cognitive Neurology

Background:

• Alzheimer's disease (AD) progression from amnestic mild cognitive impairment (aMCI) varies significantly.
• Previous functional connectivity (FC) studies had short follow-up periods, limiting insights into long-term AD progression.
• Identifying biomarkers for progression is crucial for early intervention.

Purpose of the Study:

• To investigate long-term functional connectivity (FC) differences between stable (sMCI) and progressive (pMCI) aMCI patients.
• To determine if FC patterns can predict progression from aMCI to AD over extended periods.
• To analyze cognitive changes in relation to FC alterations over time.

Main Methods:

• Utilized resting-state fMRI data from 79 aMCI participants in the Alzheimer's Disease Neuroimaging Initiative (ADNI) database with up to 48-month follow-up.
• Assessed FC using the CONN toolbox, employing local correlation and group independent component analysis to compare regional and between-network connectivity.
• Compared FC and cognitive profiles between sMCI and pMCI groups using two-sample and paired t-tests.

Main Results:

• 19 out of 79 aMCI patients progressed to AD (pMCI), while 66 remained stable (sMCI).
• Significant differences in cognitive profiles and between-network FC were observed between sMCI and pMCI groups.
• The default mode network (DMN) and salience network (SN) exhibited consistent FC differences between groups across multiple time points.

Conclusions:

• Stable and progressive aMCI patients exhibit distinct cognitive and functional connectivity (FC) profiles.
• Cognitive decline was primarily observed in the progressive aMCI (pMCI) group over time.
• The DMN and SN are key networks showing altered FC, differentiating sMCI from pMCI patients long-term.