A Longitudinal Evaluation of a Radiotracer for Use in Tau Tracking

This is a longitudinal, observational study evaluating the imaging characteristics of the tau PET radioligand \[18F\]MK-6240 in Alzheimer\'s disease (AD), Mild Cognitive Impairment (MCI) and Healthy Volunteer (HV) subjects. Up to 42 subjects, including approximately 28 MCI/mild AD subjects, up to 5 moderate AD subjects, and 9 similarly aged HV subjects will be consented and screened. Imaging procedures include \[11C\]PiB to evaluate amyloid deposition, \[18F\]MK-6240 PET, and structural MRI. All subjects complete an evaluable baseline \[18F\]MK-6240 PET scan, as well as scans at 6, 12 and 24 months post-baseline. If unable to complete the 6 month, 12 month, or 24 month visit, an 18 month and/or 30 month visit may instead be scheduled, totaling a maximum of four time points.