Sildenafil, commonly known by brand name Viagra, enhances blood flow to the brain and improves function of brain vessels in people with heightened risk of vascular dementia, a latest trial conducted at the University of Oxford has revealed.
Vascular dementia, or VaD, is the second most common type of dementia among older adults after Alzheimer's. How many people suffer from it is difficult to tell since the condition is hard to diagnose. However, the chances of its onset increases with age with 1.2 per cent to 4 per cent people over 65 likely to suffer from it.
Hypertension, diabetes, and high blood pressure are the most common causes of VaD. Hampered blood supply to small brain vessels not only adds to chances of onset of VaD, but is also responsible for 30 per cent stroke and 80 per cent brain bleeding cases.
The research's findings, if validated in a larger study, stand to be pivotal in treating patients suffering from VaD, which has limited therapies for treatment.
Dr Alastair Webb, as Associate Professor 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."
He added, "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."
Published in the journal Circulation Research, the OxHARP trial was conducted with 75 participants who had a history of minor stroke and showed signs of mild to moderate small vessel disease.
The experiment was double blind, placebo based, with participants divided into three groups, each of which was given sildenafil, placebo, and cilostazol – a similar drug – in a randomised manner.
The results were tested through MRI, ultrasound, and physiological cardio tests.
The findings revealed that sildenafil increased blood flow in both large and small brain vessels as shown in ultrasound and MRI scans. It enhanced the blood flow response to carbon dioxide, indicating improved cerebrovascular function.
Though, both sildenafil and cilostazol lowered blood vessel resistance in the brain, the former caused fewer side effects, particularly with less incidence of diarrhoea.
Professor Peter Rothwell, Founding Director of the Wolfson Centre for Prevention of Stroke and Dementia, praised Webb's findings and called them encouraging.
The findings "highlight the potential for preventing vascular dementia using existing drugs that target the underlying reduction in flow in the small blood vessels in the brain," he said.
The research was in large part funded by the Wellcome Trust and supported by the UK's National Institute for Health and Care Research.
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