Parkinson's Disease May Start in the Digestive Tract

Now there is evidence that there could be a relationship between the functioning of the digestive tract and the development of Parkinson’s disease. New research suggests that Parkinson's disease may actually start in the gastrointestinal tract and spread through the vagus nerve to the brain.  The vagus nerve (X cranial nerve or 10th cranial nerve) is a highly complex cranial nerve which runs from the brain to the abdomen.

One of the studies that indicates the importance of the vagus nerve in Parkinson’s disease examined the records of 15,000 patients who had the vagus nerve severed. This was a common treatment for ulcers between 1970-1995.  Researchers determined that patients were protected from developing Parkinson’s disease when they had the entire vagus nerve severed but not when it was only partially severed. Patients with a severed vagus nerve had half the risk of developing Parkinson’s disease compared to those with a fully or partially intact vagus nerve.  

Many patients are known to experience gastrointestinal symptoms sometimes long before being diagnosed with Parkinson's disease.  It is now thought that the common symptom of constipation which often occurs many years before they are diagnosed could be an early indicator of the relationships between neurologic and gastroenterologic pathology associated with the vagus nerve.

This research is important in helping to discover the causes of the disease and to identify risk factors for Parkinson’s so they can develop prevention models.  

Elisabeth Svensson, one of the researchers, stated, "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."

References

Elisabeth Svensson, Erzsébet Horváth-Puhó, Reimar W Thomsen, Jens Christian Djurhuus, Lars Pedersen, Per Borghammer, Henrik Toft Sørensen. Vagotomy and subsequent risk of Parkinson's disease. Annals of Neurology, 2015