Early Longitudinal Imaging in the Parkinson's Progressive Marker Initiative (PPMI) Using (18F)AV-133 (PPMI AV-133 Prodromal Imaging)

This imaging study is using a special type of PET scan (with a tracer called 18F-AV-133) to look at dopamine-producing nerve cells in the brain of people who are at high risk of developing Parkinson's disease but haven't been diagnosed yet. It is part of the larger Parkinson's Progression Markers Initiative (PPMI). This is a research imaging study — no new treatment is being tested. **You may be eligible if...** - You are over 18 years old - You are already enrolled in PPMI as a "prodromal" participant (meaning you show early warning signs of Parkinson's but do not yet have a diagnosis) - You are able to provide informed consent - If you are a woman of childbearing age, you must use highly effective contraception or be post-menopausal/surgically sterile **You may NOT be eligible if...** - You have taken certain medications in the past month that interfere with the PET scan (such as tetrabenazine, methylphenidate, reserpine, or amphetamine-type drugs) - You have a medical or psychiatric condition that makes it unsafe or impractical to participate Talk to your doctor to see if this trial is right for you.