Parkinson’s disease may originate in the appendix, according to comprehensive new research. In an analysis of health records from more than a million individuals in Sweden, researchers found nearly 20 percent reduced risk of Parkinson’s in those who had the organ removed earlier in life. The analysis, among the largest yet to investigate the disease, adds to a growing body of research linking the digestive and immune systems to Parkinson’s, according to The Guardian.
“Despite having a reputation as largely unnecessary, the appendix actually plays a major part in our immune systems, in regulating the makeup of our gut bacteria and now, as shown by our work, in Parkinson’s disease,” according to the study’s senior author, Viviane Labrie, a Van Andel Research Institute assistant professor.
Labrie notes that the discovery points toward the gastrointestinal system as a target for future Parkinson’s treatments.
The research also showed that the appendix contains alpha-synuclein, abnormally folded proteins, which play a role in the onset and progression of Parkinson’s. This may explain the link between the appendix and the neurological disease.
One unforeseen finding of the study was that these proteins are also present in healthy individuals, demonstrating that their presence alone is not enough to cause Parkinson’s. Researchers are looking for a mechanism by which these proteins actually lead to Parkinson’s. For example, in some rare cases, these proteins reach the brain stem through the vagus nerve.
According to Labrie:
“There has to be some other mechanism or confluence of events that allows the appendix to affect Parkinson’s risk. That’s what we plan to look at next – which factor or factors tip the scale in favor of Parkinson’s.”
The study was published in the journal Science Translational Medicine on Wednesday.
Researchers found additional support for the link between Parkinson’s and the appendix in a US database, in which patients who had had their appendix removed experienced an onset of Parkinson’s an average of 3.6 years later. According to Labrie, the lower risk as opposed to total absence of the disease, suggests that the appendix may not be the only part of the body where Parkinson’s can originate.
In the US about 50,000 people are diagnosed with Parkinson’s every year, and roughly half a million people suffer from the disease. Efforts to better understand the causes of the disease will help doctors assess and potentially reduce personal risk. Findings like Labrie’s may even eventually open the door to possible treatment options.