Figure 1. Hippocampal volume in relation to age and genetic risk.

Hippocampal volume (across hemispheres, shown in mm³ on the y-axis) and change in relation to (A) age (in years, x-axis) plotted with individual trajectories overlaid, (B) polygenic risk score (PGS) for Alzheimer disease (AD) (x-axis, continuous scale 0–1), (C) age (in years, x-axis) with PGS for AD set to the first (red line) and fourth quartiles (blue line) of the sample, and (D) trajectories for carriers (blue line) and noncarriers (red line) of the APOE ε4 allele. PGSs for AD shown here were constructed using single nucleotide polymorphisms with association p value <0.5 from Lambert et al.²