14 Dec Parkinson’s Disease Associated With Altered Intestinal Bacteria
Medical Research: What is the background for this study? What are the main findings?
Dr. Scheperjans: In Parkinson’s disease (PD), the first neurodegenerative changes are seen in the olfactory bulb and enteric nervous system. Correspondingly, most Parkinson’s disease patients suffer from hyposmia and gastrointestinal symptoms, frequently years before motor symptoms evolve. Therefore, it has been suggested that an environmental factor acting through the nose or gut, could be involved in Parkinson’s disease. Interestingly, those two habitats are where our body gets mostly exposed to environmental agents, including microbes. Previous attempts to identify microbes related to Parkinson’s disease pointed to Helicobacter pylori and small intestinal bacterial overgrowth, but in the end had been somewhat inconclusive. But there possibly was a signal. We saw next generation sequencing approaches as a new opportunity to revisit the microbe theory in PD. Studies of gut microbiome composition in neurodegenerative disease have not been published before, although alterations in gut microbiota have been demonstrated in many other diseases and gut microbiota are in close interaction with the central nervous system.
The fecal microbiome of Parkinson’s disease subjects clearly differed from that of matched controls and this difference was independent of the potential confounders that we assessed. The most significant finding was that the abundance of bacteria from the Prevotellaceae family was reduced by 78% in Parkinson’s disease patients. A low abundance of Prevotellaceae was 86% sensitive for PD, but rather unspecific. However, a combination of 4 bacterial families increased specificity for PD to 90%. So microbiome analysis performed quite well in distinguishing Parkinson’s disease patients from control subjects. Another interesting finding was that, within the Parkinson’s disease group, abundance of Enterobacteriaceae bacteria was related to the motor symptoms of patients. They were positively associated with the severity of postural instability and gait difficulty.
Medical Research: What should clinicians and patients take away from your report?
Dr. Scheperjans: Our study is the first to reveal a connection between gut microbiome composition and neurodegenerative disease. Gut microbiota appear as a promising biomarker candidate for Parkinson’s disease. In the future gut microbiota could hopefully be helpful in diagnosing this disorder and further research in this field is warranted.
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Scheperjans: Now we need to better understand the connection between gut microbiota and PD. For this we need prospective studies about the temporal and causal relationships. If it turned out that microbiota are actually involved in Parkinson’s disease pathogenesis, this would open up the opportunity to investigate whether microbiome modulation could be an option for treatment or even prevention of Parkinson’s disease.
We hope that our findings encourage neurologists to consider microbiome studies as a new frontier in neurological research and to be actively involved in it. This field has a great potential to give us more insight into the mechanisms behind the many neurological disorders that we still so poorly understand.
Scheperjans, F., Aho, V., Pereira, P. A. B., Koskinen, K., Paulin, L., Pekkonen, E., Haapaniemi, E., Kaakkola, S., Eerola-Rautio, J., Pohja, M., Kinnunen, E., Murros, K. and Auvinen, P. (2014), Gut microbiota are related to Parkinson’s disease and clinical phenotype. Mov. Disord.. doi: 10.1002/mds.26069