In a surprising finding, the risk of Parkinson’s disease has been tied to the presence or absence of a person’s appendix.
A large-scale epidemiological study published in the journal Science Translational Medicine reports that the removal of the appendix is associated with a decreased risk of developing the debilitating neurological disease in almost 20% of cases.
To make the finding, a team led by neuroscientist Bryan Killinger of the Van Andel Research Institute in Michigan, US, looked at the health records of 1.6 million people in Sweden, and found that having an appendectomy reduced the risk of Parkinson’s onset by 19.3%.
A second, much smaller dataset comprising 849 Parkinson’s patients was also interrogated. Those who had previously undergone appendectomy developed the disease on average 3.6 years later in life than those still intact.
The findings add further evidence to the growing conviction that the gastrointestinal tract is intimately tied up with the onset and progression of the disease.
The majority of Parkinson’s patients eventually develop gut disorders, and there is significant research to suggest that in some cases the onset of gastrointestinal problems precedes Parkinson symptoms by as long as 20 years.
Killinger and colleagues tentatively link the appendix to Parkinson’s because the vestigial organ contains high levels of a protein called alpha-synuclein, which is known to aggregate in the brains of Parkinson’s patients. The greatest risk reduction among people without an appendix was found in rural areas – suggesting that the removal of the organ may reduce the effects of pesticide exposure, which has also been linked to Parkinson’s risk.
The researchers call for further investigation, but conclude “this evidence supports the hypothesis that the appendix plays a role in the development or triggering of PD”.