Interactions Between Aging and Alzheimer's Disease on Structural Brain Networks

Area of Science:

• Neuroscience
• Medical Imaging
• Network Science

Background:

• Normative aging and Alzheimer's disease (AD) impact brain structure and function.
• The interplay between aging and AD on brain network topology remains unclear.

Purpose of the Study:

• To investigate the combined effects of aging and AD on the structural brain network topology.
• To analyze alterations in global and nodal network properties in relation to age and AD progression.

Main Methods:

• Utilized diffusion-weighted MRI data from 139 subjects (controls, early/late MCI, AD) from the ADNI database.
• Constructed structural brain networks using anatomically-constrained deterministic tractography.
• Assessed global and nodal topological properties and analyzed interactions using linear regression and ANOVA.

Main Results:

• No significant interactions between aging and AD were found for global network metrics (e.g., network efficiency, transitivity).
• Significant interactions were observed in nodal metrics, specifically the clustering coefficient and betweenness centrality, in regions like the left superior temporal and right precentral parcels.
• Confirmed age-related deterioration of structural networks in mild cognitive impairment (MCI) and AD patients.

Conclusions:

• Aging and AD interact to alter brain network topology, particularly at the nodal level.
• Nodal network changes in specific cortical regions may underlie early AD symptoms due to combined age-associated vulnerability and AD pathology.
• Findings provide insights into the complex relationship between aging, AD, and brain network integrity.