A drug which cuts the risk of heart attacks can also reduce a person's chance of having a stroke, scientists have found.
People at risk of strokes could benefit from statins
Researchers from Radcliffe Infirmary, writing in the Lancet, found statins can reduce the chance of high-risk patients having a stroke by a third.
Statins are currently given to patients at high risk of heart attacks.
But the scientists say those at risk of stroke should now also be given the cholesterol-lowering drug.
Statins lower levels of "bad" LDL cholesterol.
The Heart Protection Study looked at stroke risk in a group of more than 20,000 people for over five years.
Three thousand had already had a stroke or minor stroke, the rest had had a heart attack or another form of vascular disease.
Participants were randomly assigned to take either 40 milligrams of a statin daily or a dummy pill.
It was found that taking the statin reduced the risk of having an ischaemic stroke, caused by blood clots, by around 25%.
But the researchers say that, because a number of people stopped the treatment early, the benefits could be even greater, and adhering to the treatment could cut a person's risk of stroke by a third.
The treatment had no effect on the risk of the less common haemorrhagic stroke, which occur when ruptured blood vessels leak blood into the brain.
Professor Rory Collins, who led the research, said: "This study shows that statin therapy rapidly reduces the incidence not only of heart attacks but also of ischaemic strokes, with no adverse effect on haemorrhagic strokes, even among individuals who do not have high cholesterol concentrations.
"The study also provides definitive evidence that statin therapy is beneficial for people with a history of stroke or other cerebrovascular disease.
"National and international treatment guidelines should now be revised so that stroke risk reductions are taken into account when the initiation of statin therapy is being considered."
Professor Anthony Rudd, an expert in stroke medicine at St Thomas's Hospital, London, said: "These findings reinforce earlier research from the Heart Protection Study which was published two years ago.
"On the basis of that study, we are redrafting the national guidelines on the care of people who have had an ischaemic stroke.
"The guidelines, to be published in June, will say that people with cholesterol above 3.5 should be put on a statin."
He added: "This study would suggest that high-risk patients should probably be put on statins too.
"But there is not enough evidence to say people in the general population should be given the drug."
A second study by researchers from the US National Institute of Neurological Disorders and Stroke suggested giving stroke patients clot-busting thrombolytic drugs within 90 minutes led to the most improvement in their condition.
Guidelines suggest the drugs should be given within three hours of the stroke.