Scientists have found that people are less likely to get Parkinson’s if they’ve had a vagotomy, a treatment for stomach ulcers that severs the vagal nerve, which branches down from the brain into various tissues of the gut.

Recent epidemiological examinations of vagotomy patients whose vagus nerves were severed show that they have a lower risk of developing Parkinson’s.

What they found did not appear, at first, to be telling: Sweden’s 9,430 vagotomy patients were statistically no less likely to develop Parkinson’s over time than were the 377,200 non-vagotomized Swedes that made up the comparison group.

The study authors, from Sweden’s Karolinska Institute, the University of Southern California and elsewhere, combed through a registry of Swedish medical records to compare rates of Parkinson’s disease among people who got that surgical procedure, a vagotomy, and those who had not.

They wondered if, incidental to a vagotomy’s role as a treatment for peptic ulcers, it might also drive down the risk of Parkinson’s by blocking alpha-synuclein’s route to the brain.