Biomarkers

Area of Science:

• Neuroscience
• Biomarkers
• Brain Imaging

Background:

• Preclinical Alzheimer's disease (AD) offers a critical window for early detection and intervention.
• Electrophysiology and plasma biomarkers are promising low-invasive tools for early AD detection.
• This study investigates magnetoencephalography (MEG) network topology and plasma phosphorylated tau231 (ptau231) in unimpaired individuals with varying AD risk.

Purpose of the Study:

• To assess the relationship between MEG-derived network topology parameters and plasma ptau231 levels.
• To explore these associations in cognitively unimpaired individuals across different Alzheimer's disease risk levels.

Main Methods:

• Magnetoencephalography (MEG) recordings and plasma ptau231 concentrations were analyzed from 76 individuals.
• Minimum Spanning Tree (MST) analysis was used to calculate network topology parameters (leaf fraction, tree hierarchy, diameter) for theta, alpha, and beta bands.
• Associations were examined for the entire sample and specific risk subgroups.

Main Results:

• Higher plasma ptau231 levels correlated with increased leaf fraction and tree hierarchy, and decreased diameter in the alpha and theta frequency bands.
• These associations were significant in the overall sample and the higher AD risk group, but not in the lower risk group.

Conclusions:

• Cognitively unimpaired individuals with elevated plasma ptau231 exhibit altered brain network topology, characterized by increased integration and hub-dependency, particularly in the alpha band.
• These findings, including increased leaf fraction, tree hierarchy, and reduced diameter, align with theoretical models of early AD progression.
• Changes in brain function and organization commence early in the Alzheimer's disease trajectory.