Preliminary Diffusion MRI Findings in Hippocampal Subregions of People with Subjective Cognitive Decline

Motivation: Hippocampal subregions are differentially impacted by early Alzheimer’s pathology and may differ in their roles in information processing. However, differences in microstructure in hippocampal subregions have not been investigated in SCD. Goal(s): To investigate how hippocampal subregions (anterior, medial, and posterior) are affected in SCD. Approach: Anatomical and diffusion imaging was used to extract diffusion tensor and diffusional kurtosis imaging metrics from hippocampal subregions. Results: Reduced fractional anisotropy, decreased kurtosis, and increased mean diffusivity were found in SCD compared with a control group for the examined regions. The pattern of change varied across hemispheres and along the anterior-posterior axis. Impact: These data suggest heterogeneous pathological changes in the hippocampal microstructure in SCD indicative of neurodegeneration. These findings may inform future research on biomarker development for early AD detection.