APOE and Alzheimer disease: To summarize, our data indicated that (a) PA was associated with lower levels of AD-related plasma biomarkers in healthy control APOE ε4 noncarriers and Aβ-individuals, (b) plasma levels of Aβ1−42, but not Aβ1−40 or APP669−711, inversely correlated with brain amyloidosis, and (c) PA was associated with lower brain amyloidosis in healthy controls at risk of AD, although the analysis approaches statistical significance.