Does appendectomy increase the risk of Parkinson's disease?

June 7, 2019 / BIOON / - recently some terrible news reports show that removing the appendix will double the risk of Parkinson's disease Given that there is no cure for this neurodegenerative disease, people who have had their appendix removed may be very concerned But at this point, it's too early to worry Science is far from certain The news reports are based on a new study by researchers at Case Western Reserve University The study analyzed data from more than 62 million people in the United States Indeed, the new study found that patients with appendectomy had a higher risk of Parkinson's disease than those without appendectomy, but the risk was small in both groups The researchers found that Parkinson's disease was 0.92% in patients who had undergone appendectomy, compared with 0.29% in those who had not Photo source: risk data for Parkinson's disease at http://cn.bing.com is roughly the same as the lifetime risk of people living in the United States dying in a car crash (although many overestimate their own risk of dying in a car crash) In my opinion, the risk of Parkinson's disease after appendectomy is too small to worry about considering other risks in life For example, about half of those born in the UK after 1960 will be diagnosed with a certain type of cancer in their lifetime According to a NHS data tool, about 15% of men of my age, height, weight and similar history will have a heart attack or stroke in the next 10 years I don't smoke For people like me who smoke 20 or more cigarettes a day, the risk for 10 years is as high as 25% All in all, as we will see, in the new Parkinson's study, it's impossible to judge whether appendix surgery leads to a difference in risk Limited information we know little about the new study So far, there has been only one press release and one summary The researchers will describe the study in more detail at an upcoming meeting But at this stage, the evidence hasn't been peer reviewed, meaning that other scientists haven't had the opportunity to comment on the merits and demerits of the study The details are particularly important for the new study, as its findings are not consistent with previous studies of appendix surgery and Parkinson's disease There have been several such studies Some people agree with the latest research For example, a Danish study also found that people who had their appendix removed had a higher risk of Parkinson's disease However, a study published in 2018 based on data from millions of people in Sweden and the United States reached the opposite conclusion In other words, people who had their appendix removed had a lower risk of Parkinson's disease Another study in 2017 found no link between appendectomy and Parkinson's disease If you haven't seen this before, you might be surprised that researchers are interested in the possible link between appendicitis and Parkinson's disease - which involves changes in the brain The reason is that an abnormal form of Parkinson's related protein has been found in the gut, and there are many nerves connecting the gut and brain Photo source: http://cn.bing.com as a statistician, observational research is not qualified to comment on the biological aspects of these studies, but I do know the research based on a large number of data The research I mentioned has two ways You can find two similar groups of people, one with the appendix removed, the other without the appendix removed, and then see which group later developed Parkinson's disease Or you can find a group with Parkinson's and a similar group without Parkinson's and you can look back at how many of the two groups had their appendix removed These are called observational studies, because they only observe people and do not try to change their behavior It sounds simple But there is an obstacle to observational research If you look at the risk of Parkinson's in patients who have had appendectomy and those who have not, there are other differences between the two groups, in addition to whether they have had appendectomy For example, their average age may be older or younger, or they may have different experiences from other diseases Any difference in Parkinson's risk between the two groups may be the result of one of the other factors, known as "confounding factors," which are not directly related to appendectomy Statisticians can "tweak" the confounding factors they understand and grasp, which may make things clearer - although it's still impossible to be sure what caused it There is no statistical way to do anything about the clutter that researchers don't have data or know about It is possible that all the differences in the results of these studies are due to other differences in the relevant population, or differences in the adjustment of confounding factors So I'd like to say that we still don't know whether appendectomy will reduce the risk of Parkinson's disease, or increase the risk, or not at all We don't even know what Cleveland's new study has done to adjust for confounding factors All that was mentioned in the abstract was that they studied data on age and race Photo source: http://cn.bing.com personally, I won't pay any more attention to Cleveland's research unless it is properly published in scientific journals after peer review The main purpose of the summary is to inform other scientists, because they usually come too early in the scientific process to guide the media to understand what is happening The fact that different studies have such different results clearly shows that you should not interpret any one study too much, especially when all studies are observational No matter how good Cleveland's results are, we can't ignore other studies Scientists still need to go through a process of looking at all these different studies And, in any case, it may not become clear until more research is done Reference: [1] appendix removal: does it really increase your risk of getting Parkinson's disease? 【2】 People who have their appendix removed are THREE TIMES more likely to develop Parkinson's disease， new research warns
【3】 Having your appendix removed trebles the risk of getting Parkinson's disease， suggests largest study 【4】A S Ahmad et al Trends in the lifetime risk of developing cancer in Great Britain： comparison of risk for those born from 1930 to 1960 Br J Cancer 2015 Mar 3； 112(5)： 943-947 doi： 10.1038/bjc.2014.606 【5】 PARKINSON'S DISEASE IS MORE PREVALENT IN PATIENTS WITH APPENDECTOMIES： A NATIONAL POPULATION-BASED STUDY 【6】Elisabeth Svensson et al Appendectomy and risk of Parkinson's disease： A nationwide cohort study with more than 10 years of follow‐up Movement Disorders 2016 DOI：https：//doi.org/10.1002/mds.26761 【7】Bryan A Killinger et al The vermiform appendix impacts the risk of developing Parkinson's disease Science Translational Medicine  31 Oct 2018： Vol 10， Issue 465， eaar5280 DOI： 10.1126/scitranslmed.aar5280 【8】 Appendectomy History is not Related to Parkinson's Disease 【9】Morten Gersel Stokholm et al Pathological α‐synuclein in gastrointestinal tissues from prodromal Parkinson disease patients Annals of Neurology 2016 DOI： https：//doi.org/10.1002/ana.24648