There is a rare but scary condition known as "Narcoleptic Malignant Syndrome" or NMS. NMS may occur in people taking dopaminergic drugs (such as levodopa) for Parkinson's disease, most often when the drug dosage is abruptly reduced. According to a book I read by Dr. Grimes, stopping an agonist like ropinirole cold turkey could lead to this result. The usual advice is "titrate up" and "titrate down".

I did meet a man from Calgary once who had been diagnosed with PD 12 years earlier. He hadn't increased his sinemet dose for 10 years. He did not present with any outward manifestations of PD.

I believe the statistic is that even for patients of Neurologists, at autopsy they find that 1 of 5 or 20% of patients with a PD diagnosis do not show any signs of PD in their brains.

Clyde