Parkinson’s disease is a chronic, progressive movement disorder that affects nearly one million people living in the U.S. Although symptoms can vary from person to person, this disease is marked by tremors in the limbs, a rigid trunk, and instability of balance and coordination. There is no known cure for Parkinson’s disease, but research is beginning to reveal new potential causes in an unlikely-seeming place: the gut.

The gut is host to trillions of bacteria, many of which play key roles in the health and well-being of our bodies. In addition to helping with the most basic function of digestion, beneficial microbes in the gut also perform the following functions:

  • Control inflammation
  • Support the immune system by controlling harmful bacteria
  • Reduce the risk of allergies
  • Contribute to mood and mental health
  • Control weight

The variety of microbes in the gut is astonishing, and researchers have been connecting the presence or absence of certain types to the development of Parkinson’s disease. On the most basic level, researchers found that the presence of an H. Pylori infection could hinder the absorption of medications for Parkinson’s disease, but that was just the beginning.

It turns out that even bacteria we consider harmful can actually protect the body against potentially toxic compounds.

Researchers at the University of Michigan found that E.coli bacteria, normally associated with food poisoning and other negative illness, could prevent the formation of amyloid fibers in brain tissues. These amyloids are created when proteins fold incorrectly together and connect with each other in the wrong way at the wrong time, damaging brain tissue and leading to death.

Margery Evans, lead author of the University of Michigan study, and Matthew Chapman, principal investigator and associate professor in UM molecular, cellular, and developmental biology found that the presence of E.coli actually inhibited amyloids from entering the cells. Amyloid curli formed on the outside of a cell (or another surface, like a kitchen counter), anchoring the E. coli in place. This actually prevents them from entering into the cell itself and becoming toxic or causing death.

The finding that E.coli specifically prevents amyloids from entering the cell and becoming toxic has implications for treatment options.

Curli could be used to combat the biofilms that dangerous bacteria form. These bioshields prevent antibiotics and other treatments from reaching bacteria in the gut that is causing infection. Attacking the bioshields with amyloid curli is like using a battering ram to enter the castle so the real fight can begin.

In addition to finding a common, usually harmful bacteria that might actually help those with Parkinson’s disease to get more out of their medications, a study led by the University of Helsinki Institute of Biotechnology in Finland found that Parkinson’s patients have distinctly different gut bacteria altogether. Dr. Filip Scheperjans, a neurologist in the neurology clinic of Helsinki University Hospital, and his team found that patients with Parkinson’s disease had virtually no bacteria in the Prevotellaceae family. Another family of bacteria called Enterobacteriaceae was present in much higher amounts in those patients with severe Parkinson’s symptoms.

This particular research is in its infancy.

Dr. Scheperjans and his team have not determined if the levels of these bacteria remain stable through the course of the disease or if they fluctuate as symptoms become more severe. They are interested to know if the Prevotellaceae was eradicated due to Parkinson’s or if it was missing to begin with and thus could function as a diagnostic or predictive tool for those already at risk for the disease. If these bacteria can serve as a warning sign, then perhaps treatments that directly address their levels in the gut can be developed.

Examining the gut flora in an effort to determine if there is a connection but looking at the actual physical connection between the gut and the brain has yielded even more astonishing connections that could help doctors eventually find a cure for Parkinson’s.

In the largest study to date, doctors and researchers from Aarhus University and Aarhus University Hospital looked at the physical connection between the vagus nerve, which originates in the stomach, and the brain. They hypothesized that if idiopathic Parkinson’s disease originated in the gastrointestinal tract and was carried to the brain via the vagus nerve, then patients who had their vagus nerve surgically severed as a treatment for ulcer should not develop the disease. They looked at 15,000 patients’ data between 1975 and 1999, as severing the vagus nerve as a treatment for ulcer was common practice then.

The result?

Patients with a completely severed vagus nerve had only half the risk of developing Parkinson’s disease as those patients with only a partially severed vagus nerve (or a nerve that was entirely intact). Study researchers noted that people diagnosed with Parkinson’s often had a long history of gastrointestinal issues prior to their diagnosis, so looking closely at the vagus nerve was a logical step. The next is to look for triggers that affect the messages being sent through the vagus nerve.

Lead researcher Elisabeth Svensson believes that this next step is crucial:

“Now that we have found an association between the vagus nerve and the development of Parkinson’s disease, it is important to carry out research into the factors that may trigger this neurological degeneration, so that we can prevent the development of the disease. To be able to do this will naturally be a major breakthrough.”

The connection between the gut and the brain seems clear. For more about Parkinson’s disease, including treatment options and the latest research, visit the Parkinson’s Disease Foundation.

Image by Mark Spearman via Flickr


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