A recent study suggests that having an appendectomy is associated with an increased risk of Parkinson’s disease (PD). Mohammed Sheriff, MD, of Case Western Reserve University in Ohio, examined the medical records of 62 million patients for the research. He found that one percent of people who had an appendectomy developed PD, while less than 0.3 percent of those who did not have the procedure were diagnosed with Parkinson’s. So while the overall risk remains low, it was tripled among those who’d had an appendectomy.

As sometimes happens in science, these results are inconsistent with a previous study that came to the opposite conclusion: that appendectomy is associated with a decreased risk of PD. But what these studies have in common is demonstrating an association between the appendix and Parkinson’s. They don’t prove a cause (such as that having your appendix out definitively increases or decreases your risk of disease), but they do add to ongoing research about the gut’s involvement in PD.

Commenting on this work, Kuldip Dave, director of research programs at The Michael J. Fox Foundation, says, “There’s a growing body of evidence demonstrating a connection between the gut and Parkinson’s. Researchers have found alpha-synuclein, the primary Parkinson’s protein, in the gastrointestinal tract. So, it’s no surprise that the appendix and Parkinson’s have been linked.”

The bottom line? While these results don’t change current medical practice (appendectomy remains the main treatment for appendicitis), they do point researchers in the direction of further work to find the exact mechanisms (infection or inflammation, for example) that link the appendix to Parkinson’s.