This study focuses on early-stage Parkinson's disease (PD), a common disorder affecting the brain and body. PD symptoms include movement problems, mood changes, and sleep issues. This research looks at two types of PD: **Brain-First**, where problems start in the brain, and **Body-First**, starting elsewhere in the body. This study is being conducted in Italy and involves a thorough check-up, brain scans, and blood tests to find out how these types progress differently. Understanding these differences could help create better treatments for PD in the future. **Key Points:** - The study is observational, meaning no treatment is involved. - It will include clinical evaluations, imaging, and biomarker assessments. - Participants must be adults diagnosed with PD and able to consent. The study aims to learn more about PD's progression and help develop future therapies.