Experts say the research could have the potential to enable treatment and prevention of vascular dementia, which is caused by reduced blood flow to the brain and currently has no specific treatment.

Dr. Alastair Webb, associate professor at the Wolfson Centre for Stroke and Dementia Prevention in Oxford, said: "This is the first study to show that Viagra gets into the blood vessels in the brain in people with this condition, improving blood flow and how responsive those blood vessels are. These two key factors are associated with chronic damage to small blood vessels in the brain, the most common cause of vascular dementia. This suggests the potential of this well-tolerated and widely available drug to prevent dementia and needs to be tested in larger studies." 

The study, published in the journal Circulation Research, involved 75 people who had suffered minor strokes. They were given Viagra, commonly used to treat erectile dysfunction, in a randomized order over a three-week period. 

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The researchers observed that Viagra increased blood flow in both large and small brain vessels. 

Chronic damage to small blood vessels in the brain is not only the leading cause of vascular dementia, but also contributes to 30 percent of strokes and 80 percent of brain hemorrhages. 

High blood pressure, reduced blood flow to the brain and impaired function of blood vessels exacerbate the condition, making the study's findings "particularly important". 

Professor Peter Rothwell, founding director of the Wolfson Center for Stroke and Dementia Prevention, said: "Professor Webb's findings are very encouraging and highlight the potential to prevent vascular dementia using existing drugs that target reduced flow in small blood vessels in the brain."

Editor: David Goodman