Today’s cough syrup could turn into tomorrow’s treatment for Parkinson’s disease. Recent research in the U.K. is the latest to suggest that a common ingredient in cough syrup, ambroxol, might be able to slow down the progression of Parkinson’s.

Scientists at St. Joseph’s Health Care London conducted the year-long small study, which involved 55 patients with Parkinson’s-related dementia. The drug was safely tolerated and may have stabilized people’s symptoms, particularly people more genetically vulnerable to the neurodegenerative disease. Researchers elsewhere have already begun to test ambroxol for Parkinson’s and related dementias in larger trials.

“These findings suggest Ambroxol may protect brain function, especially in those genetically at risk. It offers a promising new treatment avenue where few currently exist,” said study author Stephen Pasternak, a cognitive neuroscientist at Lawson Research Institute, the research arm of St. Joseph’s Health Care London, in a statement from the university.

Ambroxol is commonly used as an expectorant in cough syrup, helping thin out mucus so people with respiratory illnesses can clear phlegm from their airways and breathe easier. But recently, scientists have speculated that it can also target a key driver of Parkinson’s, the accumulation of abnormal alpha-synuclein in the brain.

Studies have found that ambroxol can raise people’s levels of glucocerebrosidase (GCase), another protein that helps regulate the brain’s waste clearance system. In people with Parkinson’s, levels of GCase tend to decline as levels of abnormal alpha-synuclein rise. It’s also known that people with certain genetic mutations affecting GCase function are at higher risk for Parkinson’s. Scientists have hoped that ambroxol can indirectly lower people’s alpha-synuclein by increasing GCase, reversing or at least slowing down the progression of Parkinson’s.

The researchers randomized people with Parkinson’s-related dementia to either receive a placebo or a high dose of ambroxol (taken via pills daily) over a 12-month span. There were no severe symptoms linked to the drug’s use, the researchers found, and common adverse effects were typically gastrointestinal. People on placebo also experienced worsening psychiatric symptoms of their Parkinson’s and an increase in levels of GFAP (a blood marker of brain damage), whereas those on ambroxol appeared to stay about the same.

“This early trial offers hope and provides a strong foundation for larger studies,” Pasternak said.

The team’s results, published late last month in JAMA Neurology, were not a clear home run, however. There was overall no difference in cognition between the placebo and treatment groups, for instance. People with GCase-related genetic mutations taking the drug may have experienced improved cognition, though the sample sizes were too small to know for sure.

That said, enough evidence has built up that other scientists are taking a chance on ambroxol. There are at least three clinical trials of the drug for Parkinson’s and similar conditions linked to GCase underway right now. The largest of these trials is testing ambroxol in over 300 people with Parkinson’s over a two-year span. It will take years for these studies to wrap up, but if successful, ambroxol could very well become the first treatment able to slow down the destruction caused by Parkinson’s.