Where does Parkinson’s begin? Study claims it starts in the gut By Divina Ramirez for Prevention
An international study suggests that Parkinson’s disease may start from the gut, then slowly migrate to the brain.
In their report, published in Acta Neuropathologica, the research team revealed further evidence showing how aggregates of the alpha-synuclein protein migrate from the intestines to the brain and heart using a rodent model. Buildups of this protein in the brain are a marker of Parkinson’s disease, a chronic neurological disorder that damages neurons, affecting motor functions and causing tremors.
“For many years, we have known that Parkinson patients have extensive damage to the nervous system of the heart, and that the damage occurs early on. We’ve just never been able to understand why,” explained Per Borghammer, a clinical medicine professor at Aarhus University in Denmark and a co-author of the study. He also added that the findings could help detect the disease.
The brain-gut connection
In 1817, James Parkinson, the English surgeon to whom the disease is named after, reported that some patients with the condition – called “shaking palsy” at the time – experienced constipation. Since then, healthcare professionals have noted that constipation is among the most common symptoms of Parkinson’s.
Most studies on Parkinson’s have been focused on the brain, that is, until recently. In particular, the shift started in 2003, when researchers from Ulm University in Germany proffered the idea that Parkinson’s originates in the gut, not from the brain. In their research, the team looked at post-mortem samples of Parkinson’s patients and found that aggregates of the alpha-synuclein protein appeared in both the brain and in the enteric nervous system responsible for managing gastrointestinal functions.
Past animal studies suggest that aggregates of the alpha-synuclein protein are able to migrate from the gut to the brain through the vagus nerve, a bundle of fibers that originate in the brain stem and branch out to major organs, including the gut.
In the current study, Borghammer and his colleagues hypothesized that Parkinson’s starts in a localized segment of the gastrointestinal tract. This segment should also be one that encourages the proteins to aggregate in the first place.
To test this hypothesis, the researchers first injected alpha-synuclein into the duodenum of rats. The duodenum is the first segment of the small intestine, and past studies found that injections of alpha-synuclein in this site causes the proteins to reach the vagus nerve in record time.
The injection also caused the rats to not only accumulate harmful amounts of the protein but also exhibit signs of Parkinson’s. (Related: Supplements that may alleviate certain symptoms of Parkinson’s.)
The proteins spread predictably to the brain. Borghammer noted that the entire process involved those structures that are linked to Parkinson’s in the first place, thus confirming their hypothesis. The team noticed that the aggregates also reached the heart.
In demonstrating the mechanisms behind the spread of alpha-synuclein from the gut to the brain, Borghammer said that researchers could then predict Parkinson’s risk long before the disease can cause significant and irreparable damage to the brain by checking for alpha-synuclein in the gut.
He added that this groundbreaking finding is an important first step in the creation of medical treatments for Parkinson’s in the future.