This study looks at people with Parkinson's Disease (PD) who are taking a medicine called levodopa. Some people with PD have high levels of a chemical in their blood called homocysteine. We want to see if giving them B vitamins can lower this chemical. We also want to know if homocysteine levels affect how well the brain works. Participants need to be between 40 and 90 years old, taking at least 300 mg of levodopa daily, and able to think clearly enough to agree to join the study. They should not have poorly controlled high blood pressure or use insulin.

• The study involves open label B vitamin therapy, meaning everyone knows what they are taking.
• Participants need to visit the study site for tests and check-ups.
• This study checks if homocysteine affects brain function and if B vitamins help.