Therefore, we conducted the current study to evaluate the plasma biomarkers (Aβ1–42, Aβ1–40, Aβ1–42/Aβ1–40 ratio, T-tau and P-tau 181) and their correlations in cognitively normal individuals with AD parents and compared this data with their parents and non-demented controls (NC) (unrelated controls). Here, MAPT is linked to Alzheimer disease.