Biomarkers

Area of Science:

• Neuroscience
• Biomarkers
• Alzheimer's Disease Research

Background:

• Cognitive resilience is crucial for maintaining cognitive function in Alzheimer's disease (AD).
• Hippocampal volume is a known neurodegeneration marker, but hippocampal microstructure via diffusion-weighted imaging (DWI) may offer more sensitive insights.
• Assessing tissue integrity and cognitive function is vital in AD pathology.

Purpose of the Study:

• To investigate hippocampal microstructure as a measure of cognitive resilience.
• To examine if hippocampal microstructure moderates the relationship between tau burden and cognitive performance.
• To compare DWI metrics with hippocampal volume in relation to tau pathology and cognition.

Main Methods:

• 192 participants (14 with mild cognitive impairment) from the BIOCARD Study were analyzed.
• In vivo tau and amyloid burden were measured using positron emission tomography (PET).
• Hippocampal mean diffusivity (MD) from DWI was used to assess microstructure, with regression analyses controlling for covariates.

Main Results:

• Lower hippocampal MD (better integrity) significantly attenuated the negative association between tau burden and global cognition.
• Moderating effects were observed for episodic memory and language, but not executive function or visuospatial abilities.
• Hippocampal volume did not show a moderating effect on the tau-cognition relationship.

Conclusions:

• Better hippocampal microstructure is a sensitive biomarker for cognitive resilience in AD.
• Microstructure may partially mitigate the adverse effects of tau burden on cognition.
• DWI metrics offer valuable insights into brain mechanisms and potential outcome measures for AD interventions.