not only did I catch shigella dysentery in West Africa years ago(in my 20s), I then had a duodenal ulcer 20 years later. I makes you wonder
H Pylori And Parkinson’s Disease – The Helicobacter Study
Just over a week ago, a group of researchers presenting at the 111th General Meeting for the American Society of Microbiology revealed their research looking into the relationship between the bacterium Helicobacter pylori and the development of Parkinson’s Disease, and their results were surprising to say the least.
Given that many readers of this site are interested in H pylori moreso than ulcers, I figured I would evaluate the study and what it means for the general population (after all, over half of the World’s population is thought to have an H pylori infection).
The researchers reported that both infecting mice with H pylori and feeding mice food contaminated with dead H pylori bacteria led to movement degeneration, typical of Parkinson’s Disease (1). Here is the overview of the results (note: all bullet points reference resource 1):
•1. Aged mice developed unusual and impaired movement. This signals low levels of dopamine, suggesting that dopamine-producing cells in the brain either died or were impaired. At a basic level, Parkinson’s Disease is the unexplained dying off of dopamine-producing cells.
•2. Young mice were largely unaffected by both the feedings and infection.
•3. Mice fed dead H pylori also developed symptoms.
•4. Different strains of H pylori produced different results. In particular, the “ΔAlpAB” strain seemed to cause more advanced degeneration and increased levels of inflammation.
Now the real question is, what do these results mean for the every day person? Below, we will investigate the four primary findings.
1. Aged mice developed unusual or impaired movement
After consuming H pylori or being infected, the aged mice developed movement deficits. The researchers in this case assumed that the the deficits were due to dopamine-producing cell death, just like in Parkinsons, but these results were not confirmed.
It is possible another mechanism contributed to these movement deficiencies. It also should be known that mice do not get Parkinson’s disease, and that the mice in the study simply developed symptoms similar to Parkinson’s disease.
This is not the first time this has been proposed before. In 1965, a researcher proposed that there was a link between stomach ulcers and Parkinson’s Disease, long before H pylori was brought to the attention of the mainstream medical community (2).
2. Young mice were largely uneffected by H pylori infection
In my opinion, this is one of the most interesting results of the study. This seems to verify one of the hypotheses of the researcher behind the African Enigma research paper.
If you are unfamiliar with this paper, the researcher reports that H pylori is very prevalent in Africa whereas ulcers, stomach ulcer symptoms, and other side effects are not very prevalent at all (3). One hypothesis he uses to explain this phenomenon was the notion that people who are infected with H pylori at a young age seem to not be as strongly affected as those who are infected as adults (3).
This mouse study seems to actually corroborate this nearly 20-year old hypothesis; young mice infected with H pylori did not develop symptoms, only old mice infected or fed H pylori developed motor impairments (1).
3. Mice fed dead H pylori bacteria also developed symptoms
The point of feeding mice dead H pylori was an attempt to verify the idea that it is not infection with H pylori itself that causes Parkinson’s Disease, but rather that H pylori produces a neurotoxic compound that might kill off nerve cells. Both dead and alive H pylori possess this compound.
This hypothesis stemmed from the discovery that high rates of Parkinson’s Disease in a certain native tribe were caused by a neurotoxic seed that made up a large part of their diet. The compound produced by H pylori is very similar to the neurotoxin found in the seed which is known to cause Parksinson’s.
This piece is perhaps the strongest bit of evidence presented by the researchers. The only downside of this portion is that mice were exposed to H pylori levels which are not likely to occur naturally; contaminated human food would never contain the same levels of bacteria that was given to the mice in the study.
4. Different strands of H pylori produced different results
This conclusion was also extremely interesting. Once again, the author of the The African Enigma research paper suggested that one reason for differences in response to H pylori on different continents might be due to different strains of H pylori.
The researchers used two different types of H pylori in their experiments, and found that one strain of H pylori in particular caused significantly more damage and inflammation than the “standard” strain of H pylori bacteria (1).
It is within the realm of possibility that certain strains of H pylori might result in different effects on the human body.
H Pylori and Parkinson’s Disease – Conclusion
While the initial evidence linking H pylori and Parkinson’s is strong and based on logical grounds, it is still too soon to take anything away immediately from this particular study, and this study raises at least as many questions as it answers.
The main problem is simple: why is H pylori so much more prevalent than Parkinson’s Disease? It could be for a variety of reasons, such as:
H pylori which does not infect its host until late adulthood may be more dangerous than H pylori present for a lifelong infection;
Different strains of H pylori may exist across regions and continents, making some infections more dangerous than others;
Areas of high H pylori infection rates also tend to lack sanitation and modern medical treatments, resulting in relatively lower life expectencies. It is possible that many people with H pylori just might not live long enough to get Parkinson’s Disease;
And finally, the results of this study may not actually carry over to humans.
The bottom line is that it is far too soon to tell whether or not H pylori contributes to Parkinson’s, and we will not know until more research has been performed.
If you are still concerned about the possible links, be sure to discuss this with your doctor. Perhaps there may be some merit to testing for H pylori in the absence of symptoms if you are an otherwise healthy adult with a family history of Parkinson’s Disease. However, that should be a discussion between you and your doctor.
1. M.F. Salvatore, S.L. Spann, D.J. Mcgee, O.A. Senkovich, & T.L. Testerman. Helicobacter pylori infection induces Parkinson’s Disease symptoms in aged mice. Presentation at the 111th General Meeting for the American Society for Microbiology. 2011 May 22. New Orleans, LA.