For sensitivity analyses that included covariates of sex, age, education, and APOE ε4 allele copy number, the overall model fit was significant (F [5, 9] = 7.242, p = 0.006, R2 = 0.801) in the AD group and mGluR5 binding was the only significant predictor (β = 2.150, η2 = 0.727, p < 0.001). Here, APOE is linked to Alzheimer disease.