Inclusion Criteria (for all participants):  Signed and dated written informed consent obtained from the subject. Male participants with partners of childbearing potential must commit to the use of 2 methods of contraception, one of which is a barrier method for male participants for the study duration. Male participants must not donate sperm for the study duration. Willing and able to cooperate with study procedures. Males and females. Participants aged ≥ 70, inclusive, at the time of Screening. Judged to be cognitively normal by an Investigator based on clinical judgment.  Exclusion Criteria (for all participants):  Subject has received an investigational drug or device within 30 days of enrollment, unless in the opinion of the Investigator such medication or device will not impair subject safety or scientific integrity of the data. Contraindication to amyloid PET imaging or blood sampling. Have ever received an experimental or approved medication targeting amyloid or tau. Prior participation in other research protocols or clinical care in the last year that would result in radiation exposure exceeding the acceptable annual limit established by the U.S. Federal Guidelines (effective dose of 50 mSv, including the procedures in this clinical protocol). Pregnancy, lactating or breastfeeding. Evidence of clinically significant gastrointestinal, cardiovascular, hepatic, renal, hematological, neoplastic, endocrine, alternative neurological, immunodeficiency, pulmonary, or other disorder or disease that in the Investigator's judgment may interfere with the objectives of the study. Unsuitable veins for venipuncture.