A single-center, open-label baseline controlled imaging study designed to assess whether brain tau fibril uptake of flortaucipir as measured by PET correlates with cognitive status of individuals with and without brain tau fibrils.

This project will collect quantitative pilot data that will allow the characterization of uptake and binding of 18F-AV-1451 (also known as F 18 T807), a novel tau imaging compound, in individuals with and without brain tau fibrils. The primary goal is to develop tau imaging technique as an antecedent biomarker of cognitive decline. The investigators propose to obtain preliminary data that will support the possibility of detecting cognitive decline in its earliest stages, before the occurrence of dementia.

Inclusion Criteria:

1. Male or female participants, at least 18 years of age.
2. Cognitively normal, or with mild dementia, as assessed clinically
3. Participant is able and willing to undergo testing (MRI or CT, PET, radioactive tracer injection, LP; for those unable to undergo an MRI, CT will be used to generate regions-of-interest).
4. Pre-menopausal women will undergo a urine pregnancy test within 24 hours of drug administration.

Exclusion Criteria:

1. Has any condition that, in the Investigator's opinion, could increase risk to the participant, limit the participant's ability to tolerate the experimental procedures, or interfere with the collection/analysis of the data (for example, participants with severe chronic back pain might not be able to lie still during the scanning procedures).
2. Is deemed likely unable to perform the imaging procedures for any reason.
3. Has a high risk for Torsades de Pointes or is taking medications known to prolong QT interval.
4. Has hypersensitivity to F 18 T807 or any of its excipients.
5. Contraindications to PET, PET-CT or MR (e.g. electronic medical devices, inability to lie still for long periods) that make it unsafe for the individual to participate.
6. Severe claustrophobia.
7. Currently pregnant or breast-feeding.
8. For those electing to undergo the optional lumbar puncture: currently on anticoagulant of any form -

One hundred (100) participants over a period of approximately 5 years will be enrolled. Participants will undergo an F 18 T807 scan at the Center for Clinical Imaging Research (CCIR) at Washington University using an adaption of the protocol developed by Kolb and colleagues [7]. An MRI may be conducted if one has not been completed within the past 12 months under a related research study.

We will share the data with other researchers. They may be doing research in areas similar to this research or in other unrelated areas. These researchers may be at Washington University, at other research centers and institutions, or industry sponsors of research. We may also share the research data with large data repositories (a repository is a database of information) for broad sharing with the research community. The participant"s individual research data is placed in one of these repositories only qualified researchers, who have received prior approval from individuals that monitor the use of the data, will be able to look at this information.