New research findings propose a way one's gut bacteria may play a role in Parkinson's disease (PD). Scientists are studying the connection between the intestinal tract and PD because the nervous systems of the gut and the brain are connected, because the primary PD protein alpha-synuclein is found in the gut, and because constipation is one of the first symptoms people with PD report.

A team from the California Institute of Technology (CalTech) looked at pre-clinical models with too much alpha-synuclein. Those with complex gut bacteria performed worse on motor skills tests than models with no gut bacteria.

A press release from CalTech reports, "When gut bacteria break down dietary fiber, they produce molecules called short-chain fatty acids (SFCAs) ... Previous research has shown that these molecules also can activate immune responses in the brain. Thus, Mazmanian's group hypothesized that an imbalance in the levels of SCFAs regulates brain inflammation and other symptoms of PD."

The team implanted fecal samples from people with and without PD into the models without gut bacteria. The models with the PD samples showed higher levels of SCFAs and started exhibiting PD symptoms.

SFCAs may offer a new target to prevent, slow or stop Parkinson's, and sending a drug to the gut may be safer than one against a brain target, the CalTech team says.

The Michael J. Fox Foundation did not fund this study but has supported research that's shown differences in gut bacteria between people with and people without PD and continues to fund studies in this area.

Watch our webinar on constipation and learn more about a clinical trial at Virginia Commonweatlh University testing a drug to treat this Parkinson's symptom.