Fig. 1
Plasma a Aβ1–40, b Aβ1–42, c tau, d Aβ1–42/Aβ1–40, and e Aβ1–42xtau for enrolled clinically suspected early stage AD subjects with negative and positive amyloid PET findings. The dashed line in b denotes the cut-off value, 15.58 pg/ml, to discriminate PET− from PET+ according to the ROC curve of all subjects. Abbreviations: Aβ, Amyloid β; AD, Alzheimer’s disease; PET+, amyloid positron emission tomography positivity; PET−, amyloid positron emission tomography negativity; ROC, receiver operating characteristics. *P value < 0.05