A widely used cough medicine may help slow the progression of dementia in people with Parkinson’s disease, new research suggests.
The 12-month clinical trial tested Ambroxol – a drug used for decades in Europe to treat respiratory conditions – for its potential to protect brain function in people with Parkinson’s disease dementia.
The study included 55 participants with Parkinson’s disease dementia, divided into two groups. One received daily doses of Ambroxol, while the other was given a placebo.
Researchers monitored participants’ memory, psychiatric symptoms, and levels of GFAP – a blood marker linked to brain cell damage.
The trial was led by Dr Stephen Pasternak, a cognitive neurologist at Lawson Research Institute, the research arm of St Joseph’s Health Care London in Canada.
Parkinson’s disease dementia causes memory loss, confusion, hallucinations and mood changes. Around half of people diagnosed with Parkinson’s are expected to develop dementia within 10 years.
The study found Ambroxol to be safe, well-tolerated and capable of reaching therapeutic levels in the brain. Psychiatric symptoms worsened in the placebo group but remained stable in those taking the drug.
Participants with GBA1 gene variants – known to increase the risk of Parkinson’s – showed improved cognitive performance on Ambroxol. GFAP levels increased in the placebo group but stayed stable with Ambroxol, suggesting potential protection against brain cell damage.
“Our goal was to change the course of Parkinson’s dementia,” said Pasternak. “This early trial offers hope and provides a strong foundation for larger studies.”
Ambroxol supports an enzyme called glucocerebrosidase (GCase), produced by the GBA1 gene. In people with Parkinson’s, GCase levels are often low, allowing waste to build up in brain cells and cause damage.
Pasternak first learned about Ambroxol’s potential during a fellowship at The Hospital for Sick Children in Toronto, where it was identified as a treatment for Gaucher disease – a rare genetic disorder in children caused by GCase deficiency.
He is now applying those insights to study whether boosting GCase activity with Ambroxol can help protect brain cells in Parkinson’s-related diseases.
“Current therapies for Parkinson’s disease and dementia address symptoms but do not stop the underlying disease,” he said. “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.”
Despite its long-standing safety record in Europe, including use at high doses and during pregnancy, Ambroxol is not approved for any use in Canada or the US.
“This research is vital because Parkinson’s dementia profoundly affects patients and families,” said Pasternak. “If a drug like Ambroxol can help, it could offer real hope and improve lives.”
The trial was funded by the Weston Foundation. Pasternak and his team plan to begin a follow-up clinical trial later this year, focused specifically on cognition. The research may also have implications for other conditions, including dementia with Lewy bodies.
