New research has found a perplexing, though relatively small link between the devastating neurological illness Parkinson’s disease and having your appendix removed. But it’s still unclear just what exactly this could mean, and it’s definitely not a reason to avoid an appendectomy if you need one.
Parkinson’s disease is a neurodegenerative disorder that currently afflicts around a million Americans. At first, the movement disorder causes mild tremors that can go completely unnoticed, but over time, people lose their ability to walk, talk, and eat without difficulty; in the later stages, even the mind can be affected, leading to dementia. Though there are medications and treatments like deep-brain stimulation that can help people manage their symptoms—and the disorder itself isn’t fatal—people with Parkinson’s still die sooner than the general population, often due to complications related to the disease.
We know the protein alpha-synuclein is intimately connected to Parkinson’s, since toxic clumps of the protein (differently folded than the normal version of alpha-synuclein) called Lewy bodies are abundantly seen in the brains of sufferers. This misfolded alpha-syn is thought to help destroy the neurons responsible for producing dopamine. But while some cases of Parkinson’s are directly tied to inherited mutations for alpha-syn, we still don’t know why the majority of cases happen.
Some research, however, has shown that the abnormal protein isn’t just found in the brains of people with Parkinson’s, but is in their guts as well. That’s led to a theory that the gut—already known to affect the brain and vice-versa—could play a crucial role in the disease’s development.
The appendix comes into this picture because, despite its reputation as a useless, vestigial organ, it probably still does something useful (if not essential) in our body. So if there’s a connection between losing your appendix, as many people do when their infected organ is surgically removed, and Parkinson’s, that’s evidence the gut as a whole is causally linked to the disease.
Last October, researchers studied population data from more than a million Swedish residents and found that people who had their appendix removed were slightly less likely to develop Parkinson’s. But other research has shown that there were no clear link between the two events.
So Gregory Cooper and his team at Case Western Reserve University in Ohio decided to look with an even bigger microscope. They studied the electronic health records of more than 62 million Americans. Contrary to the October study, though, they spotted an increased risk of Parkinson’s among those who had their appendix removed, roughly three times higher. And while Parkinson’s starts becoming much more common in old age, a consistent added risk from appendix removal was even seen in those who developed it younger and across different ethnicities.
“This is the largest study to date that’s looked at this,” Cooper told Gizmodo by phone this week. “And it’s the most generalizable to the overall population, we think.”
Before anyone panics, though, none of this means that people shouldn’t get an appendectomy if they need it.
“Even with that threefold risk, it was still less than 1 percent of individuals who had an appendectomy and went on to develop Parkinson’s. So in the grand scheme of things, it’s a very low risk, and it shouldn’t dissuade anyone from getting an appendectomy,” said Cooper.
And in even the case that losing your appendix really does cause a greater risk of Parkinson’s, he added, it probably still wouldn’t be worth forgoing surgery, given the immediate, life-threatening risks of an infected appendix.
Regardless, the study does offer more circumstantial evidence that the gut is somehow involved with Parkinson’s, whether through alpha-syn or something else. “I think the bigger contribution here is that we still don’t really know what causes this debilitating disease—and this is just one more piece to the puzzle,” Cooper said.
The team’s findings were presented this week at the annual research conference Digestive Disease Week. These results are preliminary, and Cooper said they plan to submit their research to a peer-reviewed journal. Future studies could involve more closely studying the medical charts of people who have lost their appendix, he added, in order to rule out other factors that could explain both a person’s likelihood of appendectomy and Parkinson’s disease.