Amygdala subregional atrophy across ATN-defined Mild Cognitive Impairment subgroups

Area of Science:

• Neuroimaging
• Biomarkers
• Neurodegenerative Diseases

Background:

• Alzheimer's disease (AD) pathology precedes clinical symptoms, with Mild Cognitive Impairment (MCI) as a prodromal stage.
• The Amyloid, Tau, Neurodegeneration (ATN) framework stratifies MCI risk.
• Amygdala atrophy is a known biomarker, but subregional changes in ATN-defined MCI subgroups are underexplored.

Purpose of the Study:

• To investigate amygdala subregional volume changes in MCI patients stratified by the ATN framework.
• To explore the relationship between these subregional changes and cognitive function.

Main Methods:

• Analysis of MRI and cerebrospinal fluid biomarkers in 134 MCI participants.
• Classification into A-T-, A+T-, and A+T+ subgroups.
• Computation and comparison of amygdala subregion volumes and correlation with cognitive scores.

Main Results:

• Significant atrophy in bilateral basal, accessory basal, central nuclei, and right cortical-amygdaloid transition area observed in the A+T+ group.
• Volume reductions in the left central nucleus showed a positive correlation with cognitive scores.

Conclusions:

• Amygdala subregional atrophy in specific nuclei (central, basal, accessory basal, cortical-amygdaloid transition) is associated with AD pathology progression and cognitive decline.
• The findings suggest potential vulnerability of the right amygdala and its subregions in AD progression.