Cognitively unimpaired 50-90-year-old persons with each common form of APOE genotype providing blood and cerebrospinal fluid samples obtained utilizing the NCRAD protocol with storage and management through NCRAD, amyloid and tau PET and MRI brain imaging data compliant with the SCAN Initiative, and cognitive and behavioral assessment data including the NACC UDS.

Once a year, participants will provide blood samples for clinical lab analysis and genetic testing. Every two years, participants will provide cerebrospinal fluid samples, undergo PET and MRI brain scans, and complete a series of tests to assess cognitive function, risk factors, and other measures.