This study is exploring a new treatment called MTX325 for Parkinson's Disease (PD), a brain disorder affecting movement. It's in the fifth part, testing multiple doses in people with PD. The research aims to see if MTX325 can change the course of PD. Participants should be between 40 and 75 years old and meet specific health criteria. They should not have certain health conditions or allergies, especially to MTX325.

• This part of the study is ongoing, so participants need to keep up with scheduled visits.
• Participants should be stable on any medications for anxiety or depression.
• There are specific health requirements to ensure safety and accuracy in the study.

It's important to check the detailed health criteria to see if you qualify. Participants will have multiple health screenings and tests as part of the study. They need to be comfortable with these procedures and provide informed consent, meaning they understand the study and agree to participate.