Parkinson's disease patients have been given a boost by research that shows that drugs used to treat high blood pressure may slow or even halt the progression of the illness.
If the results from animal studies are confirmed in humans, it could be the biggest advance in managing the disease for 30 years.
Although treatments are available to reduce the symptoms of Parkinson's, they become less effective over time.
The new research, which is published in the online version of the journal Nature, suggests that the symptoms of Parkinson's could eventually be prevented from appearing.
Parkinson's, which mainly affects people aged 60 and over, occurs when dopamine neurons in the brain start to die.
Dopamine released by the cells is a critical chemical messenger that affects the control of movement. When dopamine supplies are lacking, movement becomes more difficult and uncoordinated.
Patients experience muscle rigidity and tremors and ultimately lose the ability to walk, talk or even pick up a glass of water.
An estimated 10,000 people in the UK are newly diagnosed each year with Parkinson's, and up to 120,000 have the disease.
Scientists at Northwestern University in Chicago discovered that isradipine, a "calcium blocker" drug for high blood pressure, angina and stroke, has the power to rejuvenate aging dopamine neurons.
Tests on mice show that the drug protects the dopamine cells from toxins that would normally kill them.
Study leader Professor James Surmeier said: "Our hope is that this drug will protect dopamine neurons, so that if you begin taking it early enough, you won't get Parkinson's disease, even if you were at risk."