Longitudinal Imaging of Microglial Activation in Different Clinical Variants of Alzheimer's Disease

This study uses PET and MRI brain scans to track changes in brain inflammation (microglial activation) in people with different forms of Alzheimer's disease over time. By studying how inflammation changes across different clinical variants of Alzheimer's, researchers hope to better understand disease progression. **You may be eligible if...** - You are 50 years old or older - You either have no cognitive impairment (healthy control) or have been diagnosed with a form of Alzheimer's disease (amnestic, posterior cortical atrophy, or logopenic variant primary progressive aphasia) - Your clinical dementia rating score is appropriate (0 for controls, 0.5 or 1 for patients) - You are fluent in English or Spanish - You are able to attend all required study visits **You may NOT be eligible if...** - You have a brain condition other than Alzheimer's disease (such as stroke or another dementia) - You have serious medical conditions that make study procedures unsafe - You cannot undergo MRI scanning (e.g., pacemaker, severe claustrophobia, or morbid obesity) - You have had significant radiation exposure from other research studies in the past year Talk to your doctor to see if this trial is right for you.