Researchers at the London School of Hygiene and Tropical Medicine have discovered a happy accident: A class of drugs typically used to treat diabetes could also reduce the risk of Parkinson’s disease in its users. The drugs have since been tested more to uncover their potential for treating Parkinson’s, and the findings of the study have been published in the journal PLOS Medicine.

The antidiabetes drug group known as glitazones, usually taken in the form of rosiglitazone or pioglitazone, was found to lower the incidence of Parksinson’s by 28 percent. Patients who were receiving medication for diabetes that did not involve glitazones did not observe the same effect.

According to the study, glitazones are mainly used to activate the peroxisome proliferation-activated gamma (PPARy) receptor in a variety of cells within different organs of the body. When glitazones activate PPARy receptors, they reduce insulin resistance in patients, which can ultimately help manage diabetes. However, researchers have known that this receptor serves many different purposes in the body, and only a few of them have been studied.

Previous studies conducted in rats and in vitro have found that glitazones can potentially reduce the risk of Parkinson’s disease. Until now, though, no one has examined whether incidences of Parkinson’s decrease among patients who have taken glitazones. This study is the first.

Receiving their funding from The Michael J. Fox Foundation for Parkinson’s Research, the team of researchers examined more than 160,000 patients with diabetes in the UK. In order to compare the effects of glitazones to other diabetes treatments, researchers gathered electronic health records from the UK Clinical Practice Research Datalink, matching 44,597 glitazone users with 120,373 non-glitazone users based on age, sex, primary care physician, and diabetes treatment stage. Patients’ records were then tracked from 1999, when they were introduced to the glitazone treatments, to 2013 in order to see how many were subsequently diagnosed with Parkinson’s during this time.

Even after adjusting for risk factors that are linked to Parkinson’s, like smoking and head injury, researchers observed a 28 percent reduction in instances of Parkinson’s disease in patients who were taking glitazones. Furthermore, researchers found that this risk reduction was only associated with the current treatment of glitazones, and that those who had taken the drug in the past but stopped did not receive the same benefits.

“We often hear about negative side effects associated with medications, but sometimes there can also be unintended beneficial effects,” senior author Dr. Ian Douglas said in a recent press release. “Our findings provide unique evidence that we hope will drive further investigation into potential drug treatments for Parkinson’s disease. It’s thought that around one in 500 people are affected by Parkinson’s, and to date no effective treatments have been found to directly tackle the neurodegenerative aspect of the disease.”

Dr. Ruth Brauer, another researcher, also believes that her team’s findings may open doors for currently sparse treatments for Parkinson’s. “Our results suggest that treatments which activate the PPARy receptor in the same way as glitazones could be promising targets in future drug research,” she said. “Although our study only looked at people with diabetes, we believe it’s likely that the protective effect of glitazones may also be seen in people without diabetes.”

The researchers conceded that their study did not look at patients who had already been diagnosed with Parkinson’s, and therefore do not know if glitazones slow the progression of the disease. They hope to examine this factor in future studies, along with glitazones’ potential for treatment.

Source: Brauer R, Dexter D, Smeeth L, et al. Glitazone Treatment and Incidence of Parkinson’s Disease among People with Diabetes: A Retrospective Cohort Study. PLOS Medicine. 2015.