Serotonin Release in Premotor and Motor PD

This study is using brain scans (PET and SPECT imaging) to measure serotonin levels in people with Parkinson's disease — both early-stage (before movement symptoms appear) and later-stage. Understanding serotonin's role may lead to better treatments for Parkinson's. **You may be eligible if...** - You are 25–85 years old - You have been diagnosed with Parkinson's disease (either early or advanced stage) - Women of childbearing age must not be pregnant and must use effective contraception during the study and for 3 months after - Males must agree to use contraception and avoid donating sperm during and for 3 months after the study - You can give written informed consent **You may NOT be eligible if...** - You are outside the 25–85 age range - You are pregnant or breastfeeding - You are unwilling or unable to use contraception - You are unable to follow the study requirements Talk to your doctor to see if this trial is right for you.