We will conduct a Tau PET scan in cognitively normal older adults, enrolled in the Aging Brain Cohort Dedicated to Diversity Study (ABCD2-Tau) study at the University of Pennsylvania's Penn Memory Center/Alzheimer's Disease Core Center (PMC/ADC).Study duration will generally be a one-day study visit for PET imaging, but all subjects will be followed annually as part of their participation in the ABCD2 study. Findings from this study will likely provide insight into the mechanisms and distinctions of age-related cognitive decline and that of preclinical Alzheimer's Disease.

Inclusion Criteria:

1. Males and females African Americans ≥ 65 years of age.
2. Part of the ABCD2 longitudinal cohort, protocol 844047, of the PMC/ADCC with consensus conference designation of normal cognition.
3. ABCD2 longitudinal visit must be completed or scheduled to be completed within 1 year prior to the [18F]AV-1451 TAU PET scan.
4. A brain MRI must be performed within 1 year prior to their study [18F]AV-1451 TAU PET scan date and be deemed of adequate quality that the scan may be used for study analysis, including 3T high-resolution imaging of medial temporal lobe structures.
5. An amyloid PET scan completed or scheduled within 1year of their study [18F]AV-1451
6. Women must be post-menopausal or surgically sterile.

Exclusion Criteria:

1. Have any medical or psychiatric conditions that, in the opinion of the investigator, would compromise the subject's safety or successful participation in the study, including major depression and prior head trauma.

2. Have evidence of structural abnormalities such as major stroke or mass on MRI that is likely to interfere with analysis of the PET scan.

3. Inability to tolerate or contraindication to imaging procedures in the opinion of an investigator or treating physician.

4. Have a history of significant ongoing alcohol or substance abuse or dependence based on self-report.

5. Women of child bearing potential

   • The inclusion / exclusion criteria will be ascertained through self-report in conjunction with any medical history available through the participant's medical or research records (EPIC or the ADC database)*

Study population includes cognitively normal, older adult (>65 years old) black or African American participants