Sildenafil- known most commonly as ‘viagra’- improves brain blood flow and blood vessel function in patients at risk of vascular dementia. The findings may pave the way for treatment and prevention options for vascular dementia. The corresponding study was published in Circulation Research.
Chronic damage to small blood vessels in the brain is the leading cause of vascular dementia, and contributes to 30% of strokes and 80% of brain bleeds. Sildenafil is used to treat erectile dysfunction by increasing blood flow to the required area. It also treats pulmonary hypertension by relaxing the blood vessels in the lungs to facilitate blood flow.
In the current study, researchers investigated whether sildenafil improves cerebrovascular dysfunction. To do so, they recruited 75 participants with an average age of 70 years old who had experienced a minor stroke and who showed signs of mild to moderate small vessel disease. Participants received sildenafil, a placebo, and cilostazol (a similar drug) separately for three weeks in a randomized order. They also underwent cardiovascular physiology tests, ultrasound, and functional MRI scans.
Ultimately, the researchers found that sildenafil did not affect cerebral pulsatility compared to the placebo and cilostazol. It did, however, increase blood flow in large and small brain vessels as assessed by ultrasounds and MRI scans. The drug was also shown to enhance blood flow response to carbon dioxide, suggesting improved cerebrovascular function. Both sildenafil and cilostazol lowered blood vessel resistance in the brain, however, sildenafil caused fewer side effects- especially diarrhea.
"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,” said study author Dr. Alastair Webb, Associate Professor at the Wolfson Centre for Prevention of Stroke and Dementia at Oxford University, in a press release.