Having your appendix removed could cut the odds of developing Parkinson’s by a fifth.
The brain disease, suffered by comedian Billy Connolly and actor Michael J Fox, may start in the appendix decades before symptoms appear.
Previously seen as a useless organ, the tiny appendix harbours a protein which plays a key part in Parkinson’s disease.
In rare cases, this protein may escape into the digestive tract and travel up the body to the brain.
Its importance to the human body – if any – has long been the subject of speculation, but now scientists believe the appendix could be a contributor to the onset of Parkinson’s
Researchers studied almost 1.7 million people, finding those with their appendix removed were 19.3 per cent less likely to get Parkinson’s disease.
That is likely to be due to alpha synuclein, a protein discovered in the appendix which kills off brain cells in people with Parkinson’s, causing tremors and difficulty walking.
While taking people’s appendix out to protect them from Parkinson’s is unrealistic, the findings could lead to a drug which targets the alpha synuclein protein to stop it leading to Parkinson’s.
Dr Viviane Labrie, a co-author of the study from Van Andel Research Institute in Michigan, said: ‘Despite having a reputation as largely unnecessary, the appendix actually plays a major part in our gastrointestinal immune systems, in regulating the makeup of our gut bacteria and now, as shown by our work, in Parkinson’s disease.’
She added: ‘Location is everything. So it’s normal for this clumped protein to be in the appendixes of people but if it were to enter the brain, that could lead to Parkinson’s disease.’
Evidence is growing that neurodegenerative disorders like Parkinson’s may begin in the gut, which experts describe as a ‘second brain’ due to its high number of nerve cells also found in the brain, called neurons.
The appendix is part of the immune system in the digestive tract, which is why scientists wanted to look at it.
Checking a Swedish database of 1,698,000 people over more than 50 years, they found people whose appendix had been removed were much less likely to develop Parkinson’s later in life.
The rate of Parkinson’s following an appendix removal was 1.17 cases per 1,000 people, compared to 1.4 cases per 1,000 in the general population.
This finding may be explained by the protein alpha synuclein, which scientists found in the appendix of 46 out of 48 people who had the organ removed.
Previous studies in rodents show this protein is able to travel from the digestive tract up a long nerve to the brain, where it can jump between brain cells on a path of destruction.
The appendix could even trigger this process, as it affects gut bacteria, which could play a role in the build-up and movement of the protein.
However the findings, published in the journal Science Translational Medicine, were most significant for people with a removed appendix in rural areas, who may be more at risk of Parkinson’s disease because of exposure to pesticides.
Dr Labrie said: ‘We’ve shown that clumped alpha-synuclein is present in the appendix of all of us and we think that in rare events, if it were to escape the appendix and enter the brain, this could lead to Parkinson’s disease.
‘This is important for how we think of Parkinson’s disease origins but also has implications for treatments.’
Around 127,000 people in the UK are thought to have Parkinson’s disease, which causes severe mobility problems.
Further analysis by US researchers of more than 800 patients with Parkinson’s found that the onset of Parkinson’s disease symptoms was delayed by more than three years if someone’s appendix had been removed more than 30 years ago.
Professor Tom Foltynie, from University College London Institute of Neurology, said: ‘This is strong, highly valuable, long term epidemiological evidence providing further links between gut pathology and the subsequent risk of developing Parkinson’s disease.’
Claire Bale, head of research at Parkinson’s UK, said: ‘The finding that removing the appendix early in life can reduce risk of Parkinson’s suggests that it may play a contributing role in the loss of brain cells.
‘This builds on previous research indicating that, for some, Parkinson’s starts in the gut.
‘There is much still to learn about how surgical approaches, such as removing the appendix, may stop the progression of toxic proteins that cause Parkinson’s.
‘However, these approaches are unlikely to eliminate the condition, as Parkinson’s may also start in other areas of the body or brain.’