This study is for people aged 40-80 with early Parkinson's Disease (PD) who might have a certain genetic trait. It looks at how safe and effective a drug called NEU-411 is. The study uses a special DNA test to find people whose PD is affected by a gene called LRRK2. NEU-411 is a drug taken by mouth that may help by blocking LRRK2 activity in the brain. The study compares NEU-411 to a placebo (a pill with no medicine) over a year. After this, participants can continue in an open-label extension (OLE) for an additional 26 weeks, where everyone gets the real drug. To join, participants must have early PD and a specific genetic test result. People with other severe health issues or certain types of PD cannot join.

• The study lasts up to 78 weeks with regular visits.
• Participants may receive a placebo or NEU-411 during the first year.
• The study includes a safety check 2 weeks after the treatment ends.