Parkinsons is thought to be misdiagnosed lyme disease in many. If someone has parkinsons, I strongly suggest being tested for Lyme. Not with the Elysa test your doctor will give you - it gives TONS of false negatives. I was bit by a tick 20 years ago and tested negative over and over for 20 years. There are other newer, better tests. I'll give an article with a link to the labs that do the testing.
Also, I use glutathione IV's because with lyme, the bugs create toxins in the body. The glutathione helps the body get rid of the toxins. I know my doctor has many, many parkinsons patients who take glutathione IV's for the parkinsons as a part of their regular program. I hear it is really helpful to them. I would think NAC could help, but I would think the IV's make a much greater impact. They do make a huge impact for me.