Amygdala subregional atrophy across ATN-defined Mild Cognitive Impairment subgroups

Background: Alzheimer's disease (AD) pathology begins years before clinical symptoms, with Mild Cognitive Impairment (MCI) as a prodromal stage. The ATN framework (Amyloid, Tau, Neurodegeneration) aids in stratifying MCI risk. While amygdala atrophy is a recognized biomarker, amygdala subregional changes across ATN-defined MCI subgroups remain underexplored. Methods: This study analyzed MRI data and cerebrospinal fluid biomarkers from 134 MCI participants classified into A-T-, A+T-, and A+T+ subgroups. The volumes of amygdala subregions were computed and compared among the different groups. Furthermore, we also investigated the relationship between the altered brain regions and cognitive function. Results: Significant atrophy was observed in the A+T+ group within bilateral basal, accessory basal, central nuclei, and right cortical-amygdaloid transition area compared to other groups. Volume reductions in the left central nucleus correlated positively with cognitive scores. Conclusion: Amygdala subregional atrophy, particularly in the central, basal, accessory basal, and cortical-amygdaloid transition nuclei, is linked to AD pathology progression and cognitive decline. The findings suggest a potential vulnerability of the right amygdala and suggest these subregions may be associated with AD-related pathological progression.