Viagra could help to stave off dementia.
The little blue pill is used to treat erectile dysfunction in men but a study has shown that it improves blood flow to the brain and could help to prevent problems with memory.
Scientists think that Viagra - also known as sildenafil - could be used to treat vascular dementia, a form of the disease that is caused by reduced blood flow to the brain.
There are currently no therapies available for the specific treatment of vascular dementia.
Dr. Alastair Webb, study author at the Wolfson Centre for Prevention of Stroke and Dementia at Oxford University, said: "This is the first trial to show that sildenafil gets into the blood vessels in the brain in people with this condition, improving blood flow and how responsive these blood vessels are.
"These two key factors are associated with chronic damage to the small blood vessels in the brain, which is the commonest cause of vascular dementia.
"This demonstrates the potential of this well-tolerated, widely available drug to prevent dementia, which needs testing in larger trials."