Before you take any PD specific meds please look at cardio exercise to slow disease progression.
Obviously, depending on other health issues, it's not always an option. I was 60 years old when diagnosed. I was 30 plus pounds overweight due to work and life loads (wife, three kids in college and/or finishing high school).
On the day I was diagnosed, my Petite, barely 5 foot tall 60 plus year old treating Neuro, looked me in the eye and said the following: "I am going to tell you one thing "buddy". "One thing only, buddy, and your going to listen to me, and listen to me good, buddy!"
She then got really close to me, almost in my face and said the following (almost verbatim): "There is only one thing known to medical science that slows PD disease progression and it was proven in a double blind study"! She went on: "Only hard cardio exercise slows disease progression. I am not talking about walking around the block buddy! I am talking about hard breathless cardio exercise. 15 minutes is good, 30 minutes is better and anything over that is "gravy" (her words exactly)! Every day!"
I am now 12 years into my journey with PD. I exercise 3 to 5 or more days per week riding my bike, hiking, or spinning at the gym. I hate to swim or I would be adding that into my regimen. I get hard breathless cardio on each ride or hike, sometimes 90 minutes or more each time I go out.
I am 72.5 years old now and I am not, I repeat, am not medicated for Parkinson's symptoms related to any movement disorder with one exception. The exception is that Parkinson's can also deteriorate your memory and cognition and now at 72 years old I have the beginnings of early moderate memory loss which may eventually lead to Dementia. Considering the memory diagnosis occurred shortly after the PD diagnosis, I feel I am still way better off than if I had stayed sedentary on a high carb diet.
The evidence is out there that hard cardio will slow Parkinson's Disease progression.