According to a recent study published in Circulation Research, sildenafil — more commonly known as Viagra — may reduce the risk of vascular dementia.
After participants took the drug for three weeks, the scientists measured positive changes in the behavior of blood vessels in the brain. Arginine
The study, called the OxHARP trial, lays the foundation for future clinical trials.
Viagra, first designed to treat angina, rose to fame in the late 1990s as an effective treatment for erectile dysfunction.
Because it is a relatively safe drug and affects a number of organs, such as the heart, liver, kidney, and brain, it is a good candidate for drug repurposing.
For instance, scientists have already investigated whether sildenafil might help treat conditions including chronic pain, cancer, depression, kidney disease, and more.
The latest study asks whether Viagra might help reduce the risk of developing vascular dementia.
Vascular dementia is a form of dementia caused by impaired blood flow or damaged blood vessels in the brain. It often occurs after a stroke. As the second most common form of dementia after Alzheimer’s disease, vascular dementia accounts for 15–20% of dementia cases in North America and Europe.
Medical News Today spoke with José Morales, MD, a vascular neurologist and neurointerventional surgeon at Pacific Neuroscience Institute in Santa Monica, CA.
Morales, who was not involved in the new study, told Medical News Today that “there are treatments available that can help manage the symptoms and slow the progression of the disease.” However, “There is no cure,” so identifying risk factors and ways to reduce those risks is important.
Cerebral small vessel disease (CSVD) is one such risk factor. CSVD is an umbrella term for a number of conditions that affect small blood vessels in the brain.
MNT reached out to one of the study’s authors, Alastair Webb, MSc, a consultant neurologist at Imperial College London in the United Kingdom. He provided an outline of CSVD:
“Small vessel disease is chronic damage to the small blood vessels deep inside the brain, resulting in them becoming narrow, blocked, and leaky. This damage occurs to some extent in most people as they get older, but it is much more severe in some, often due to having high blood pressure for a long time.”
“The resulting damage may further reduce blood flow to the deep part of the brain resulting in strokes and dementia,” he explained.
In the recent study, the scientists recruited 75 people with neurological signs of CSVD.
Every participant received 3-week regimens of sildenafil, placebo, and cilostazol — a treatment for vascular disease. Each course of drugs was separated by a “washout” period of at least 1 week.
Testing all three drugs on all participants is called a crossover trial. These studies are powerful because each participant acts as their own control. They also require fewer participants to achieve statistically meaningful results.
The researchers focused on the following measures.
MNT asked Webb why they decided to investigate sildenafil:
“It causes blood vessels to open up, to increase blood flow and the responsiveness of blood vessels,” he said. “As such, it had the right type of action to improve the blood flow problems seen in our patients, but it was unclear whether it worked in the brain in the same way.”
The researchers found that sildenafil did not improve cerebral pulsatility compared with placebo. Although Webb “had reason to believe that it would reduce pulsations,” the team was not overly surprised that it did not work in this way.
Importantly, though, sildenafil did improve cerebrovascular reactivity and resistance, and cerebral blood flow compared with placebo.
Compared with cilostazol, Viagra performed similarly but produced fewer side effects, such as diarrhea.
“Overall, the improved cerebrovascular dynamics with sildenafil provide a new potential treatment to prevent progression of [cerebral small vessel disease] that needs testing in clinical trials.”
Although it is still early days, this is a step toward understanding how to reduce the risk of vascular dementia.
MNT spoke with Rakesh C. Kukreja, PhD, professor of internal medicine at Virginia Commonwealth University School of Medicine in Richmond, who was not involved in the study. On why Viagra might help reduce vascular dementia risk, Kukreja said:
“Sildenafil is a potent inhibitor of the enzyme phosphodiesterase 5 (PDE5), which breaks down the powerful vasodilator molecule cyclic guanosine monophosphate (cGMP).”
“By preventing the breakdown of cGMP, sildenafil promotes the relaxation of blood vessels and improves blood flow. Therefore, the enhanced cerebral blood flow and reduced vascular resistance from sildenafil treatment might influence the risk of dementia,” he said.
It is worth mentioning that this study’s results line up with earlier research.
For instance, a study using a rodent model of vascular dementia found that Viagra improved cognitive ability and memory. Other rodent studies produced similar findings.
Also, studies in a human population concluded that Viagra usage was linked with a reduced risk of developing Alzheimer’s. Similarly, Kukreja outlined another study involving “insurance claim data for 7.23 million individuals.”
In this study, he explained, “sildenafil was associated with a 69% reduction in the risk of developing Alzheimer’s disease.”
While further research is needed into Viagra and vascular dementia, there are lifestyle factors that can make a difference to an individual’s risk.
MNT spoke with Dr. Tim Beanland, head of knowledge at the Alzheimer’s Society who was not involved in the study. He outlined some lifestyle risk factors for vascular dementia:
“We know that what’s good for the heart is good for the brain, so a healthy diet and lifestyle, including not smoking or drinking too much alcohol, can help to lower your risk of dementia and other conditions like heart disease, stroke, diabetes, and some cancers.”
For individuals who already have dementia, he told MNT that “there is growing evidence to suggest that regular exercise, looking after your health, and keeping mentally and socially active can help to reduce the progression of dementia symptoms.”
The results of this study suggest that sildenafil may help reduce the risk of vascular dementia in people with CSVD. However, it only measured changes to aspects of cerebral blood flow over a relatively short period of time.
To get a clearer picture of whether Viagra and similar drugs truly can reduce risk, scientists will need to follow people for years to assess whether their risk is reduced.
Webb plans to continue this line of investigation:
“It is very important to follow up on this work. We need to do some further studies to work out the best dose of the drug, and the best drug from this group of drugs to take on further,” he told MNT.
“We are aiming to test it in a much larger trial to understand if it not only improves blood flow to the brain but also to test whether this reduces the risk of stroke and dementia,” he added.
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