APOE and Alzheimer disease: This significant interaction was due to a stronger correlation between FCVRS and RVI-AD in APOE-ε4 carriers (r = 0.35, p = 4·10−5 vs. r = 0.02, p = 0.95) (Fig. 2A) and the difference in correlation coefficients was significant (z = 2.9, p = 0.004).