A drug used to treat enlarged prostate gland may be an effective treatment for Parkinson's disease, according to an international team of scientists.
Terazosin helps relieve benign prostatic hyperplasia (BPH) by relaxing the muscles of the bladder and prostate gland.
Researchers believe, however, that it has another beneficial effect on Parkinson's-damaged brain cells.
The drug could slow the progression of Parkinson's ̵
They studied thousands of patients with both BPH and Parkinson's.
Their findings, published in the Journal of Clinical Investigation, suggest that the alpha-blocker drug protects brain cells from destruction.
Parkinson's is a progressive disease of the brain for which there is currently no cure.
Existing Parkinson's treatments may help with some symptoms but will not slow or reverse the loss of neurons associated with the disease.
Terazosin may help by activating an enzyme called PGK1 to prevent the death of these brain cells Researchers at the University of Iowa in the US and the Beijing Institute for Brain Disorders in China say.
When they tested the drug on rodents, it seemed to slow or stop the loss of nerve cells.
In order to investigate whether the drug has the same effect on humans, they looked in the medical records of millions of US patients for men with BPH and Parkinson's.
They studied 2,880 Parkinson's patients taking terazosin or similar medicines for PGK1, and a comparison group of 15,409 Parkinson's patients who received another treatment for BPH and had no effect on PGK1.
Patients targeted for PGK1 appeared to perform better on the symptoms and progression of Parkinson's disease. Researchers believe further studies are needed in clinical trials that are due to begin this year.
The lead researcher Michael Welsh says it is premature to talk about a cure, but the results could change the lives of Parkinson's patients.
"We no longer have treatments that alter the course of this neurodegenerative disease," she says.
"This is a terrible condition, because as our population ages, Parkinson's disease becomes more common."
"So this is really an exciting area of research.
Given that terazosin has a proven track record in the treatment of BPH, it should be achievable if clinical trials are successful.  In the studies, which take several years The drug is compared to placebo to ensure that it is safe and effective in Parkinson's.
Co-researcher Dr. Nandakumar Narayanan, who treated Parkinson's patients, said, "We need these randomized controlled trials to prove that these medicines are really disease modifying.
"If so, that would be a great thing."
Prof. Parkinson's David Dexter in the UK said: "These exciting results show that terazosin may have the potential to slow the progression of Parkinson's, which is urgently needed to help people live longer.
" Animal models and studies People who are already taking the drug show promising signs that need further investigation. "