Investigation of Inflammation in Alzheimer's Disease and Related Dementias (ADRD) Using [11C]-CS1P1

This imaging study is using a special PET scan with a radioactive tracer called [11C]-CS1P1 to look at brain inflammation in people with Alzheimer's disease and related dementias (ADRD). The goal is to better understand the role of inflammation in these conditions. **You may be eligible if:** - You are 50 or older, of any gender or race - You can provide written informed consent (or have a legal representative do so) - If joining the dementia group: you have a clinical or biomarker diagnosis of mild cognitive impairment or early dementia due to Alzheimer's disease or related dementias **You may NOT be eligible if:** - You have a known allergy to the PET tracer or its components - You cannot undergo PET, CT, or MRI scanning (e.g., certain medical implants, severe claustrophobia) - You are pregnant or breastfeeding - You are currently undergoing radiation therapy - You have had significant heart problems in the past 6 months (arrhythmias, unstable angina, decompensated heart failure) - You have significant anemia (hemoglobin below 9.9) - You have participated in other radiation research studies that would push you over annual radiation dose limits Talk to your doctor to see if this trial is right for you.