Common cough medicine could slow dementia in Parkinson's patients, study hints

Independent

01-07-2025

A commonly sold cough syrup in Europe could potentially slow down progression of dementia in patients with Parkinson's disease, a new study suggests.
Nearly half of those diagnosed with Parkinson's develop dementia within 10 years, with progressively worsening memory loss, confusion, hallucinations, and mood changes, which affect patients, families, and the healthcare system.
'Current therapies for Parkinson's disease and dementia address symptoms but do not stop the underlying disease,' said neurologist Stephen Pasternak from Western University in Canada.
Now, a new year-long clinical trial suggests that the cough medicine Ambroxol – used safely for decades in Europe – can potentially slow the development of these symptoms.
The small scale study, published in the journal JAMA Neurology, monitored 55 participants with Parkinson's dementia, assessing their memory, psychiatric symptoms, and the blood marker GFAP linked to brain damage.
One group of participants received Ambroxol daily while the other received a placebo.
Researchers found that the drug was safe, well-tolerated and reached therapeutic levels in the brain.
While psychiatric symptoms worsened in the placebo group but remained stable in those taking Ambroxol, scientists said in a statement.
'Individuals receiving placebo showed a clinically meaningful worsening in neuropsychiatric symptoms, whereas those receiving ambroxol remained stable,' researchers wrote in the study.
Those with high risk variants of a key gene linked to dementia showed improved cognitive performance on Ambroxol, they said.
GFAP levels increased in the placebo group, but stayed stable with Ambroxol, suggesting that the cough medicine may have the potential to protect the brain from faster deterioration under Parkinson's.
'Ambroxol was safe, well-tolerated, and demonstrated target engagement,' scientists wrote, however adding that the drug's clinical effect on cognition was 'not confirmed' in the study.
Previous studies have shown that Ambroxol supports a key enzyme called glucocerebrosidase (GCase), whose levels are low in Parkinson's patients.
Researchers previously found that Ambroxol could help treat the rare genetic disorder Gaucher disease in children, which is caused by a deficiency of GCase.
When this enzyme doesn't work properly, waste can build up in brain cells, leading to damage.
'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,' Dr Pasternak said.
'If a drug like Ambroxol can help, it could offer real hope and improve lives,' he said.
While the cough medicine is approved in Europe for treating respiratory conditions, with a long-standing safety record, including use at high doses and during pregnancy, it is not approved for any use in the US or Canada.
Scientists hope the pharmacological data from this study could help conduct larger clinical trials to test the effectiveness of Ambroxol in slowing dementia symptoms.