Episodic memory of APOE ε4 carriers is correlated with fractional anisotropy, but not cortical thickness, in the medial temporal lobe

We observed a strong, positive correlation between FA in the EWM and memory performance, which was driven solely by APOE ε4 carriers. These effects were significant while controlling for age, sex, EWM volume and EC thickness. Although EC thickness was significantly reduced in ε4 carriers, we did not find a relationship between EC thickness and memory performance. Thus, increased susceptibility of the WM structures underpinning the entorhinal-hippocampal network, offers a plausible explanation for the earlier onset of cognitive decline previously reported in APOE ε4 carriers.