A Phase 0, Open Label, Multi-center Exploratory and Safety Study of [F-18]T807

\[F-18\]T807 is being developed as a diagnostic radiopharmaceutical for PET imaging of the human brain.

Siemens Molecular Imaging (SMI) is seeking to determine if \[F-18\]T807 might be useful as a non-invasive assessment tool in the clinical evaluation of subjects with conditions associated with tau protein aggregates, such as Alzheimer's disease. The information collected under this exploratory study will not be used for diagnostic purposes, assessments of the participant's response to therapy or for clinical management of the participants. However, this exploratory study will provide baseline information on the safety, biodistribution, and dosimetry of \[F-18\]T807. These data will aid in the design of future studies of \[F-18\]T807 in patients with Alzheimer's disease. Overall, this study will provide initial data that inform the development of \[F-18\]T807 as the first PET imaging agent for human tau protein related pathology.

Eligibility Criteria:
Inclusion Criteria; Low Probability for AD Participants (Group 1)

* Participant has reached his or her 55th birthday at the time of informed consent (Participant is male or female of any race / ethnicity)
* Participant provides written informed consent
* Participant is capable of complying with study procedures
* Participant is capable of communicating with study personnel
* Participant understands and speaks English
* Participant has at least an 8th Grade education
* In the Investigator's opinion, participant has a low probability of being currently positive for AD as determined by a Mini Mental State Examination (MMSE ≥ 28) defined in APPENDIX VI of protocol T807000, IND 114102
* Participant has no significant hepatic or renal disease as defined by previous medical history and lab results are within the following ranges:
* Total bilirubin within 2x institutional upper limits of normal
* AST (SGOT) ≤ 2.5 x institutional upper limits of normal
* ALT (SGPT) ≤ 2.5 x institutional upper limits of normal
* Creatinine ≤ 2x institutional upper limits of normal
* BUN within 2x institutional upper limits of normal

High Probability for AD Participants (Group 2)

* Participant has reached his or her 55th birthday at the time of informed consent (Participant is male or female of any race / ethnicity)
* Participant or participant's legally acceptable representative provides written informed consent
* Participant is capable of complying with study procedures
* Participant is capable of communicating with study personnel
* Participant understands and speaks English
* Participant has at least an 8th Grade education
* In the Investigator's opinion, participant has a high probability of being currently positive for AD that is determined by a Mini Mental State Examination (MMSE \< 17) defined in APPENDIX VI of protocol T807000, IND 114102.
* Participant has no significant hepatic or renal disease as defined by previous medical history, and lab results are within the following ranges:
* Total bilirubin within 2x institutional upper limits of normal
* AST (SGOT) ≤ 2.5 x institutional upper limits of normal
* ALT (SGPT) ≤ 2.5 x institutional upper limits of normal
* Creatinine ≤ 2x institutional upper limits of normal
* BUN within 2x institutional upper limits of normal

Exclusion Criteria; All Participants

* Female participant is pregnant or nursing
* Participant has prior history of stroke or other condition of the head or neck that, in the Investigator's opinion, might affect circulation to the head or image interpretation
* Participant has other neurodegenerative disease that is associated with cognitive impairment or dementia
* Participant has a medical condition that might be associated with elevated amyloid levels, such as amyloid angiopathy, familial amyloidosis, chronic kidney dialysis, Down's syndrome
* Participant has a history of significant cerebrovascular disease
* Participant has previously received \[F-18\]T807 at any time
* Participant has been involved in an investigative, radioactive research procedure within the past 14 days
* Participant has any other condition or personal circumstance that, in the judgment of the Investigator, might interfere with the collection of complete data or data quality
* Participant has a history in the last five years of significant prescription or non-prescription drug or alcohol abuse, including but not limited to marijuana, cocaine, heroin or derivatives