Autoimmune Features of Neurodegenerative Disorders

This study is investigating whether Parkinson's disease and other neurodegenerative conditions (diseases that damage the brain over time) may have an autoimmune component — meaning the immune system may be mistakenly attacking the brain. Researchers will compare immune system markers in Parkinson's patients versus healthy controls. **You may be eligible if...** - You are 55 or older - You have a confirmed clinical diagnosis of Parkinson's disease (with tremor, rigidity, or slow movements that respond to dopaminergic medication), with motor symptoms starting after age 45, OR - You are a healthy person aged 55 or older with no family history of Parkinson's disease, willing to participate as a control - You are willing to undergo genetic testing **You may NOT be eligible if...** - You have atypical features suggesting a different type of Parkinson-like disorder - You have a history of dementia - You have had cancer in the last 3 years (excluding skin cancer) - You have an autoimmune disease or immune system disorder - You are on chronic immune-modifying medications (such as oral steroids or rituximab) Talk to your doctor to see if this trial is right for you.