Effect of apolipoprotein E phenotype on the association of plasma amyloid β and amyloid positron emission tomography imaging in Japan

Abstract Introduction The plasma concentration of beta-amyloid (Aβ) has been considered another biomarker of Alzheimer's disease and was reportedly associated with cortical Aβ accumulation. Methods We analyzed 28 subjects with apolipoprotein E4 (ApoE4; E4 group) and 89 subjects without ApoE4 (non-E4 group) to determine the association between cortical Aβ accumulation by standard uptake value ratio with [ 18 F]florbetapir positron emission tomography and plasma Aβ 1–40 and Aβ 1–42 . Results Aβ 1–42 /Aβ 1–40 correlated significantly with mean regional [ 18 F]florbetapir standard uptake value ratio in the non-E4 group ( R 2  = 0.06, P  = .02) but not in the E4 group, and receiver operating characteristic curve analysis for Aβ 1–42 /Aβ 1–40 in the non-E4 group showed sensitivity (92.9%) and specificity (45.9%) with a cutoff value of 0.150 for Aβ positivity. Discussion We verified that the correlation between Aβ 1–42 /Aβ 1–40 and Aβ accumulation differed according to ApoE phenotype. The high sensitivity of plasma Aβ 1–42 /Aβ 1–40 for Aβ positivity in non-E4 subjects indicated a possible role of plasma Aβ 1–42 /Aβ 1–40 as a screening biomarker before amyloid positron emission tomography in clinical settings.