Parkinson's United Kingdom said the findings were the most compelling evidence yet that the disease's origins lie outside the brain.
The scientists also found an interesting fact, the essence of which lies in the relationship between the operation to remove the Appendix and development of Parkinson's.
The reasoning is due to surgically removed appendix tissue becoming a storage space for abnormal protein that, if it makes its way to the brain, becomes the trademark of the tremor-inducing brain disease.
Although they do not advise that people go and have their appendix removed, as this is not a sure protection against Parkinson's disease.
The exact cause of Parkinson's and an effective prevention/cure have not been found. Researchers promise to continue looking into the link between the appendix and the neurodegenerative disease. "That's what we plan to look at next - which factor or factors tip the scale in favor of Parkinson's". Scientists are working on determining its causes (there could be multiple) but it appears it could have both genetic and environmental components, according to the Mayo Clinic. "There has to be some other mechanism or confluence of events that allows the appendix to affect Parkinson's risk", said Labrie.
Scientists have increasingly wondered whether there are Parkinson's disease triggers in the gut.
The study found that of the 1,144,745 Swedes who did not have appendectomies, 1,608 had Parkinson's, but of the 551,003 who had, only 644 had Parkinson's.
The new study - though not the first to suggest that Parkinson's can start in the gut, or even in the appendix - was one of the largest ones done to date.
Researchers also found those with Parkinson's who had an appendectomy had a later onset of the disorder by an average of 3.6 years.
The study showed that nearly everyone in this study had alpha-synuclein protein present in their appendix. It is possible for alpha-synuclein to travel from the gastrointestinal tract via the vagus nerve and reach the brain.
In Parkinson's disease, toxic proteins accumulate in the brain and kill nerves, especially those linked to movement.