Fig. 1.

Scatterplots of FDG ratio with partial volume correction (PVCY) as a function of age in representative cortical regions. Estimated mean FDG ratio for each age is shown with a solid line for APOE ε4 carriers and a dashed line for APOE ε4 noncarriers. Estimates are from a linear regression model with age, APOE ε4 genotype, and their interaction. Age was fit with restricted cubic splines with 3 knots at ages 45, 65, and 80 years to allow for nonlinearity in the FDG-age relationship. The 7 regions depicted are medial temporal, lateral temporal, lateral parietal, prefrontal, primary visual cortex, posterior cingulate and/or precuneus, and the Alzheimer signature meta-ROI. Abbreviations: APOE, apolipoprotein E; FDG, ¹⁸F-fluorodeoxyglucose; ROI, region of interest.