Parkinson's disease may be rooted in the gastrointestinal tract and spreads through the vagus nerve to the brain, a new study suggests.

Researchers from Aarhus University and Aarhus University Hospital reported their findings, in the Annals of Neurology, after noting most Parkinson's disease patients also suffered from gastrointestinal symptoms before the disease was diagnosed, according to Science Daily.

"Patients with Parkinson's disease are often constipated many years before they receive the diagnosis, which may be an early marker of the link between neurologic and gastroenterologic pathology related to the vagus nerve ," noted lead researcher Elisabeth Svensson.

In tracking a large number of patients who underwent a procedure to have the vagus nerve severed — once commonly done to treat ulcers — the researchers found they were half as likely to develop Parkinson’s over a 20-year period.

But patients who had only had a small part of the vagus nerve severed where not protected.
"We have conducted a registry study of almost 15,000 patients who have had the vagus nerve in their stomach severed,” said Svensson.

“Between approximately 1970-1995 this procedure was a very common method of ulcer treatment. If it really is correct that Parkinson's starts in the gut and spreads through the vagus nerve, then these vagotomy patients should naturally be protected against developing Parkinson's disease."

Parkinson's disease is a chronic and neurodegenerative disease that affects one out of every 1,000 people.