We found that (1) model‐free GQI was able to resolve the complex microstructures and connections within the anterior hippocampus; (2) the variance of dMRI measurements in hippocampal layers was generally higher in AD than HC or PART; and (3) the accumulations of Aβ in the SM/SL/SR layers and tau in the SP layer were significantly correlated with the dMRI metrics in AD. The gene discussed is MAPT; the disease is Alzheimer disease.