The Parkinson’s Disease-Appendectomy Debate
Is having your appendix removed a risk factor for developing Parkinson’s Disease (PD) or can it prevent PD?
In 2015, a team of Portuguese scientists published a paper stating that people that had their appendix removed were more likely to develop Parkinson’s Disease (Mendes, 2015). However, in 2019, Mohammed Sheriff of Case Western Reserve University examined 62 million patient records and found that 1% of people who had an appendectomy developed PD opposed to only 0.3% of people without the procedure developing the disease. On one hand we have a 2015 study saying “Don’t get your appendix out you will get Parkinson’s!” and a 2019 study saying “Get your appendix out to prevent Parkinson’s!”. It's hard to tell in this murky area of scientific declarations who might be right, and why we even care about the appendix.
The appendix has been consistently proclaimed as one of the most mysterious areas of the human body. People sometimes get it out or leave it in with no real impact on their livelihoods. In general, the appendix is a “dead end” turn in the intestines that is home to many of the bacteria known to keep our guts healthy. The appendix tends to only jump into the spotlight in times of appendicitis, or when a pathogen such as a bad bacteria or virus causes massive inflammation, leading to swelling or even bursting of the appendix (John Hopkins Medicine, 2022). To prevent bursting, which can spill bad bacteria into the rest of the body doctors quickly intervene by removing the appendix all together. But what does a bursting bacteria filled piece of intestine have to do with PD?
A-synuclein is a pathogenic marker of PD that has been found to be toxic to certain dopamine-producing brain cells that leads to PD. It has now been found that α-synuclein is present in the appendix of people with PD. Furthermore, this protein can spread between the cells of the intestine into the gastrointestinal muscle layer and up through specific nerves to reach the brain, which could lead to the appearance of PD motor symptoms (Chen et al., 2021). It is not known how or why the appendix produces α-synuclein, but its presence is yet another link between the gut and PD.
Despite evidence pointing to α-synuclein presence in the appendix, our controversy still remains. In the past 3 years two meta-analyses have been released trying to solve this issue once and for all; and were entirely inconclusive. They each screened hundreds of publications, and together compared over 9,000,000 people’s data. The result: “there was no significant difference in the emergence of PD between patients with and those without appendectomy history” (Ishizuka et al., 2021), and ‘future studies are needed to clarify the role of the appendix in PD’ (Lu et al.,2019). So, for now what we know is the appendix is still a mysterious part of the body that may (or may not) have a role in the development of PD.
Appendicitis. (2021, December 9). https://www.hopkinsmedicine.org/health/conditions-and-diseases/appendicitis
Chen, Y., Wu, W., Zhao, S., Lv, X., Hu, J., Han, C., Wang, G., Wang, S., Bo, P., Zhang, J., Gui, W., Tang, Q., Liu, Q., Zhu, S., & Yu, F. (2021). Increased Accumulation of α-Synuclein in Inflamed Appendices of Parkinson’s Disease Patients. Movement Disorders, 36(8), 1911–1918. https://doi.org/10.1002/mds.28553
Ishizuka, M., Shibuya, N., Takagi, K., Hachiya, H., Tago, K., Suda, K., Aoki, T., & Kubota, K. (2021). Appendectomy Does Not Increase the Risk of Future Emergence of Parkinson’s Disease: A Meta-analysis. The American Surgeon, 87(11), 1802–1808. https://doi.org/10.1177/0003134821989034
Lu, H., Shen, Q., Xie, D., Zhao, Q., & Xu, Y. (2020). Lack of association between appendectomy and Parkinson’s disease: A systematic review and meta-analysis. Aging Clinical and Experimental Research, 32(11), 2201–2209. https://doi.org/10.1007/s40520-019-01354-9
Mendes, A., Gonçalves, A., Vila-Chã, N., Moreira, I., Fernandes, J., Damásio, J., Teixeira-Pinto, A., Taipa, R., Lima, A. B., & Cavaco, S. (2015). Appendectomy may delay Parkinson’s disease Onset. Movement Disorders: Official Journal of the Movement Disorder Society, 30(10), 1404–1407. https://doi.org/10.1002/mds.26311
Palacios, N., Hughes, K. C., Cereda, E., Schwarzschild, M. A., & Ascherio, A. (2018). Appendectomy and risk of Parkinson’s disease in two large prospective cohorts of men and women. Movement Disorders: Official Journal of the Movement Disorder Society, 33(9), 1492–1496. https://doi.org/10.1002/mds.109
Rachel Dolhun, M. S. V. P. M. C. (n.d.). The Appendix: What’s the Link to Parkinson’s? | Parkinson’s Disease. Retrieved June 27, 2022, from https://www.michaeljfox.org/news/appendix-whats-link-parkinsons