Parkinson's disease linked to gut bacteria
A recent study led by Filip Scheperjans M.D, from the Helsinki University Central Hospital (HUCH), in partnership with researchers from the University of Helsinki, examined the microflora (see Probiotics Learning Lab for more glossary terms) of patients suffering from Parkinson’s disease. (Parkinsons disease is a progressive, neurodegenerative, movement disorder that belongs to the group of conditions called motor system disorders).
It was observed that Parkinson’s patients have a different balance of bacteria in their guts, as compared to healthy controls. The most noticeable differences reported were that they appear to have much less intestinal bacteria from the Prevotellaceae family, and much more from the Enterobacteriacaea family. Interestingly, symptom severity seems to correspond directly with levels of Enterobacteriacaea. The higher the levels of this bacteria the more severe the Parkinson's symptoms.
What is not understood is whether this altered microbiota is in some way responsible for the onset or worsening of disease symptoms, or whether the dysbiosis occurs as a result of the Parkinson’s disease. Is this imbalanced gut flora the ‘chicken or the egg', so to speak?
If low levels of Prevotellaceae bacteria turns out to be a factor in the onset of the disease, more research will be necessary to determine what protective qualities these bacteria are exerting. How are they seemingly supporting the proper functioning of the nervous system? Equally, if high levels of Enterobacteriacaea are causative in the disease process then, why is this? Do they perhaps produce toxic metabolites that damage the nervous system in some way? Or, do they affect neurotransmitter levels, for example? All of these questions will need answering.
Scheperjans explains that his team are “currently re-examining these same subjects to determine whether the differences are permanent and whether intestinal bacteria are associated with the progression of the disease and therefore its prognosis, In addition, we will have to see if these changes in the bacterial ecosystem are apparent before the onset of motor symptoms. We will of course also try to establish the basis of this connection between intestinal microbiota and Parkinson's disease -- what kind of mechanism binds them."
The research is at an early stage at the moment, but Sheperjans and his colleagues are hoping that their findings could be used to a) develop a means of testing for Parkinsons disease, perhaps enabling earlier detection, and b) potentially lead to a way to treat or prevent the disease through the manipulation of the gut microflora.
Update September 2017:
A new article by Sherwin, et al. (2017) looked into reviewing new developments in research, focusing on the links between the microbiota and neurological conditions like Parkinson’s disease. They reviewed a number of studies that identified factors in the microbiota that could be linked to Parkinson’s disease. Parkinson’s patients often report gastrointestinal symptoms such as constipation even before motor related symptoms, which could suggest that the ‘microbiota-gut-brain’ axis is impacted in this disease. 2 A recent study by Bedarf et al., also corroborated the finding of Scheperjans et al., and identified that there was indeed a reduction in Prevotella species and an increase in Akkermansia muciniphilia in Parkinson’s patients. Provetella species are thought to produce Mucin, which helps with enhancing the integrity of the intestinal barrier. So, there is a possibility that a reduction in Provotella species could lead to intestinal permeability. 2, 3, 4
Another study found that patients suffering with Parkinson’s disease also had significantly lower amounts of short-chain fatty acids (SCFA).5 SCFAs like butyrate are mostly secreted by anaerobic bacteria like Bifidobacteria in the colon, and they have been linked in numerous studies to play a role in brain health. See Kerry’s blog here, in the Probiotics Learning Lab, for more information on this topic.
Although these studies have identified different imbalances in the gut microbiota, they all suggest that dysregulation in the microbiota could lead to factors that are thought to affect Parkinson’s disease.
If you are interested to read more about new research into the potentially neuro-protective effects of probiotics, check out the following blog posts, over in the Probiotics Learning Lab:
1. Filip Scheperjans, Velma Aho, Pedro A. B. Pereira, Kaisa Koskinen, Lars Paulin, Eero Pekkonen, Elena Haapaniemi, Seppo Kaakkola, Johanna Eerola-Rautio, Marjatta Pohja, Esko Kinnunen, Kari Murros, Petri Auvinen. Gut microbiota are related to Parkinson's disease and clinical phenotype. Movement Disorders, 2014; DOI: 10.1002/mds.26069
Image source: 1. http://memespp.com/justice-balance-scale/ 2. http://imgarcade.com/1/carbapenem-resistant-enterobacteriaceae/
2 E. Sherwin, T. G. Dinan and J. F. Cryan, "Recent developments in understanding the role of the gut microbiota in brain health and disease," ANNALS OF THE NEW YORK ACADEMY OF SCIENCES, pp. 1-22, 2017.
3. Bedarf, J.R., F. Hildebrand, L.P. Coelho, et al. 2017. Functional implications of microbial and viral gut metagenome changes in early stage l-DOPA-na¨ıve Parkinson’s disease patients. Genome Med. 9: 1–13.
4. Scheperjans, F., V. Aho, P.A.B. Pereira, et al. 2015. Gut microbiota are related to Parkinson’s disease and clinical phenotype. Mov. Disord. 30: 350–358.
5. Unger, M.M., J. Spiegel, K.-U. Dillmann, et al. 2016. Short chain fatty acids and gut microbiota differ between patients with Parkinson’s disease and age-matched controls. Parkinsonism Relat. Disord. 32: 66–72.