I'd like to know why the people getting vagotomies did so, as it might point to another explanation for their lower Parkinson's acquisition rate. But this is interesting.
"Scientists have found more new evidence that Parkinson's could start in the gut before spreading to the brain, observing lower rates of the disease in patients who had undergone a procedure called a truncal vagotomy.
The operation removes sections of the vagus nerve - which links the digestive tract with the brain - and over the course of a five-year study, patients who had this link completely removed were 40 percent less likely to develop Parkinson's than those who hadn't."
http://www.sciencealert.com/scientists-find-another-sign-that-parkinson-s-starts-in-the-gut-and-not-in-the-brain
"Scientists have found more new evidence that Parkinson's could start in the gut before spreading to the brain, observing lower rates of the disease in patients who had undergone a procedure called a truncal vagotomy.
The operation removes sections of the vagus nerve - which links the digestive tract with the brain - and over the course of a five-year study, patients who had this link completely removed were 40 percent less likely to develop Parkinson's than those who hadn't."
http://www.sciencealert.com/scientists-find-another-sign-that-parkinson-s-starts-in-the-gut-and-not-in-the-brain