Parkinson’s disease may start in the appendix, not the brain. People are less likely to get the condition if they had their appendix out decades previously. And a toxic compound found in the brains of people with this disease has now been spotted in the appendix. Source(s): http://stm.sciencemag.org/content/10/465/eaar5280 https://www.newscientist.com/article/2184110-parkinsons-disease-may-start-in-the-appendix-and-travel-to-the-brain/