Individuals who have had their appendixes removed have a nearly 20% lower overall risk for developing Parkinson’s disease later in life, according to research published in Science Translational Medicine.
Labrie, PhD, of the Center for Neurodegenerative Science at Van Andel Research Institute, told Healio Gastroenterology and Liver Disease that as researchers come to understand Parkinson’s as more than just a movement disorder, they decided to focus on the gastrointestinal tract, where symptoms can surface years before motor symptoms.
“The hallmark pathology of Parkinson’s disease in the brain is Lewy bodies, which contains a clumped form of a protein called alpha-synuclein. There is evidence that Parkinson’s disease pathology, this clumped alpha-synuclein protein, is detectable in the GI tract, even many years before the onset of Parkinson’s motor symptoms,” she said in an email. “In the brain of Parkinson’s patients, one of the first places where alpha-synuclein clumps are detected is at the terminal where the gut nerve connects to the brain, and this pathology advances from this point to other brain areas as the disease progresses.”
To study the relationship between the gut and Parkinson’s disease, Labrie and colleagues focused on the appendix. They analyzed data from a large Swedish database (n = 1,698,000) in which patients were followed for up to 52 years to assess Parkinson’s risk among individuals with and without an appendectomy.
From this group, researchers identified 551,647 individuals who had appendectomy and matched these patients with two control participants based on age, sex and location. Overall, they identified 2,252 patients with Parkinson’s, excluding patients with secondary parkinsonism and diseases that might cause parkinsonism.
Researchers found that appendectomy was linked with a decrease in risk for Parkinson's disease
Labrie and colleagues found that incidence of Parkinson’s was lower in the appendectomy group (1.6 per 100,000 person years; 95% CI, 1.46–1.75) compared with the control group (1.98; 95% CI, 1.87–2.1). That means the overall risk for Parkinson’s was significantly decreased by 19.3% among people who underwent an appendectomy, the researchers wrote.
Using another dataset, Labrie and colleagues found that onset of Parkinson’s was delayed by 3.6 years in patients who had their appendix removed at least 30 years before disease onset relative to non-surgery patients (95% CI, 1.03–6.13).
After examining the appendixes of healthy individuals, investigators found an abundance of alpha-synuclein.
“This is important because clumped alpha-synuclein was previously attributed to Parkinson’s,” Labrie said. “And now we find that — in the appendix — clumped alpha-synuclein is not a unique feature of Parkinson’s disease but is present in everyone.”
Labrie cautioned that researchers were not suggesting that the appendix causes Parkinson’s or that everyone should have their appendixes removed. While having alpha-synuclein in the appendix appears to be normal, Labrie said factors that trigger its spread to the brain could be the difference between people who do or do not develop Parkinson’s.
Since inflammation in the gut has been associated with Parkinson’s risk, Labrie said it is important for gastroenterologists to understand the early signs of Parkinson’s.
“Be aware that Parkinson’s may start outside of the brain, in the GI tract — specifically the appendix — may be a site of origin,” she said. “Learn about the early signs of Parkinson’s disease, the non-motor symptoms, and be vigilant for these. For their patients that already have Parkinson’s, they should ask their patients about these non-motor symptoms and consider treating these in addition to the motor symptoms.” – by Alex Young
Disclosures: Labrie reports no relevant financial disclosures. Please see the full study for all other authors’ relevant financial disclosures.