Viagra improves blood flow to the brain and could help prevent dementia, new research suggests.

A study by University of Oxford researchers found that the drug, also called sildenafil, enhances the function of brain blood vessels in patients at increased risk of the condition.

Experts suggest the research may have the potential to transform the treatment and prevention of vascular dementia – caused by reduced blood flow to the brain, which currently lacks specific therapies.

Dr Alastair Webb, Associate Professor at the Wolfson Centre for Prevention of Stroke and Dementia at Oxford, 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.”

The study, published in Circulation Research, involved 75 people who had experienced a minor stroke and showed signs of mild to moderate small vessel disease.

Everyone received Viagra – commonly used to treat erectile dysfunction – a placebo, and cilostazol (a similar drug) over three-week periods in a random order.

The researchers found that Viagra increased blood flow in both large and small brain vessels, and both Viagra and cilostazol lowered blood vessel resistance in the brain.

Additionally, the Viagra caused fewer side effects compared with cilostazol, particularly with less incidence of diarrhoea.

The researchers say further larger trials are needed to confirm these findings and explore sildenafil’s potential in preventing vascular dementia on a broader scale.

The research was funded by the Wellcome Trust and supported by the National Institute for Health and Care Research.