More On the Parkinson’s/Gut Bug Connection

This past Thursday I promised you the 2nd big story of last week:

We’ve known for a while that Parkinson’s seems to start with an “infection”  in the gut.  I’ve talked about this several times on this blog.  Well, it looks like there is a very close association between Parkinson’s and Helicobacter pylori (H.pylori), the bacteria that causes stomach ulcers.  A review article in the Journal of Parkinson’s Disease compiled all current information on the link and found 4 major findings:

Firstly, people with PD are 1.5 to 3 times more likely to have H.pylori infections than those without the disease.  Secondly, those with PD and H.pylori have worse motor function than those with PD but without H.pylori infection.  Thirdly, eradicating H.pylori improves motor function…and fourth, eradication also improves absorption of L-dopa, the medication used to replace the lost dopamine in the brain.[i]

Holy smokes, right?!

Scientists do not yet know if H.pylori infection predisposes people to getting PD, if it is responsible for the progression of the disease (and if so, will treating it alter disease progression) or if it’s even a direct cause of PD.  So, as of right now, they are 4 main hypotheses that need to be tested:

  1. Toxins produced by pylori may damage neurons
  2. The infection causes a huge inflammatory response, which, in turn, damages the brain
  3. H.pylori disrupts the normal gut flora and this dysbiosis is the ultimate culprit
  4. H.pylori interferes with the absorption of L-dopa

From the conclusion of the paper:

“The gut is being increasingly considered as a critical focal point in the pathology of PD. This gut pathology may be multifactorial, involving H. pylori, intestinal microflora, inflammation, misfolding of alpha-synuclein in the gut and brain, cholesterol and other metabolites, and potential neurotoxins from bacteria or dietary sources.  Eradication of H. pylori or return of the gut microflora to the proper balance in PD patients may ameliorate gut symptoms, L-dopa absorption and motor functions.”[ii]

What I am puzzled about is this:  about 50% of the population of the world is thought to carry H.pylori, with higher rates in the industrialized world.[iii]  (In fact, I’ve always wondered, knowing how common it is, why the bacteria cause ulcers only a small percentage of people.)  What are the factors that might make it become toxic in some?  As of now, no one knows but…I suspect this work will be aggressively pursued in the near future and of course, I will follow it closely.



[ii] David J. McGee, Xiao-Hong Lu, Elizabeth A. Disbrow. Stomaching the Possibility of a Pathogenic Role for Helicobacter pylori in Parkinson’s Disease. Journal of Parkinson’s Disease, 2018; 8 (3): 367 DOI: 10.3233/JPD-181327

[iii] Brown, LM. Helicobacter pylori: epidemiology and routes of transmission.  Epidemiologic Review. 2000. 22(2):283097.

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