Flortaucipir 18F PET Imaging in BIOCARD Study

Inclusion Criteria: * Males or females that have provided consent and are currently enrolled in BIOCARD study * Ability to tolerate PET scan procedures * Ability to provide informed consent for study procedures Exclusion Criteria: * Has condition(s) that could augment risk to participant or compromise ability to tolerate experimental procedures or interfere with analysis of the study data as determined by the investigator * Has a history of risk factors for Torsades de Pointes or taking medications known to cause QT prolongation. * Has electrocardiogram acquired prior to initial flortaucipir scan that clinically contradicts subject's participation in the study as determined by the investigator. Bazett's corrected QT (QTcB) interval must be assessed and not exceed accepted values (458 msec in males, 474 msec in females). * Females of childbearing potential who are not surgically sterile, not refraining from sexual activity, or not using reliable contraceptive methods. * Has hypersensitivity to flortaucipir * Has a currently clinically significant infectious disease, endocrine/metabolic disease, pulmonary/renal/hepatic impairment, or cancer that could impact study participation or scan results in the opinion of the investigator. * Has a non-study related radiopharmaceutical imaging/treatment procedure within seven days prior to flortaucipir imaging visit. * Is unsuitable for a study of this type in the opinion of the investigator.