F 18 T807 Tau PET Imaging of Alzheimer's Disease

This study is using a specialized brain scan (called F18-T807 tau PET imaging) that detects abnormal protein buildup in the brain linked to Alzheimer's disease, to better understand how early this buildup appears and how it relates to memory and thinking changes. **You may be eligible if...** - You are 18 years of age or older - You have normal thinking and memory, or only mild memory difficulties - You are able and willing to undergo PET and MRI brain scans, including an injection of a small amount of radioactive tracer - Women who have not yet reached menopause will need to take a pregnancy test **You may NOT be eligible if...** - You have a medical condition that would make scanning unsafe or would interfere with results - You take medications or have heart conditions involving abnormal heart rhythms - You are allergic to the imaging agent used in the scan - You cannot lie still in an MRI or PET scanner, or have severe claustrophobia - You have a pacemaker or other metal implant that prevents MRI - You are currently pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.