Here's a summary article of a large epidemiological study: http://news.wustl.edu/news/Pages/20150.aspx http://news.wustl.edu/news/Pages/20150.aspx Doing the m

Here's a summary article of a large epidemiological study: http://news.wustl.edu/news/Pages/20150.aspx http://news.wustl.edu/news/Pages/20150.aspx Doing the math (450,000 cases out of 36,000,000 million Medicare recipients in the US), the adult incidence rate of Parkinson's is 0.0125, or 1.25%. Sadly, I can't find a full copy of the study which isn't behind a pay wall. But, from the summary, it appears Parkinson's has some "clustering" based on both genetic and environmental factors. The text under the map on the article indicates areas in red have an adult incidence rate of 13.8% or more, so experiences such as yours are normal (albeit frightening). So, yes, you're right to question that 1% statistic. It isn't sufficient to describe the situation at all when standing by itself.