Amyloid-β accumulation in relation to functional connectivity in aging: A longitudinal study

Area of Science:

• Neuroscience
• Neuroimaging
• Aging Research

Background:

• Healthy aging is characterized by pathological and functional brain alterations.
• Amyloid beta (Aβ) accumulation is a hallmark of aging, impacting brain function.
• Understanding the interplay between Aβ and functional brain organization is crucial for aging research.

Purpose of the Study:

• To investigate the longitudinal relationships between amyloid beta (Aβ) accumulation and functional brain organization in healthy aging.
• To explore how Aβ deposition influences functional connectivity (FC) over time.
• To examine the impact of functional brain networks on Aβ propagation.

Main Methods:

• Utilized a longitudinal, multimodal imaging dataset (OASIS-3, n=300) with at least 2-3 follow-up visits per participant.
• Employed Positron Emission Tomography (PET) with Pittsburgh Compound-B (PIB) for quantifying brain Aβ accumulation.
• Applied resting-state functional MRI (rs-fMRI) to measure whole-brain functional connectivity (FC) and analyzed longitudinal changes using linear mixed-effect models.

Main Results:

• Limbic and frontoparietal networks exhibited greater annual Aβ accumulation and slower FC decline during aging.
• Baseline Aβ deposition in the amygdala network was associated with a slower decline in its FC.
• Functional connectivity within limbic, default mode (DMN), and frontoparietal networks accelerated Aβ propagation.
• Somatomotor and visual network connectivity accelerated Aβ spread to limbic, frontoparietal, and DMN regions.

Conclusions:

• Slower functional connectivity decline in key brain hubs may counteract increased Aβ accumulation in aging.
• Functional connectivity strength appears to be a critical factor in the propagation of Aβ between brain regions.
• These findings offer insights into the complex dynamics of brain aging and Aβ pathology.