It’s the little blue pill that can aid performance in the bedroom and is heralded as a passion saver by older men, but now scientists are saying that the erectile dysfunction pill Viagra could also have benefits for the brain.

New research published in Nature Aging has found that the male impotence drug, which aids sexual function by opening the tiny arteries in the penis, may prevent people from developing Alzheimer’s. The US scientists from the Cleveland Clinic claim that it could reduce the chance of developing the disease by as much as 69 per cent.

The researchers analysed medical insurance records of more than seven million people and were able to follow those who were prescribed the drug. 99 percent of people taking Viagra, also known as sildenafil, did not develop Alzheimer’s compared to 95 per cent who were not using the erectile dysfunction pill.

Alzheimer’s researcher Dr Catherine Hall, senior lecturer in psychology at the University of Sussex, welcomed the new research. “A challenge in finding a successful treatment for Alzheimer’s disease is that symptoms only appear after significant neuronal death has occurred – and this cannot then be reversed.”

Dr Ivan Koychev, a senior clinical researcher at the University of Oxford, who was not involved in the study, said it was “an exciting development”.

The lead investigator in the new study, Dr Feixiong Cheng, said the findings were encouraging, but that further research is needed and they are now planning a randomised clinical trial “to test causality and confirm sildenafil’s clinical benefits for Alzheimer’s patients”.

“People with the early signs of Alzheimer’s disease are, on average, less sexually active. So sildenafil use could be a spurious correlation – aka a red herring,” explains Dr Jack Auty, lecturer in the medical sciences at the University of Tasmania.

But how could an erectile dysfunction drug reduce the risk of Alzheimer’s?

In a separate small scale study, the scientists found that high doses of sildenafil lowered the amount of tau, an Alzheimer’s-related protein, in brain cells and increased brain cell growth in lab studies on human tissue.

Scientists are also exploring whether Viagra might help people at risk of vascular dementia – the second most common form of dementia after Alzheimer’s – which occurs when reduced blood flow damages the brain.

However, dementia isn’t the only non-sexual problem that erectile dysfunction drugs might help treat.

Viagra was originally designed to treat heart disease and has been shown to improve heart function in patients with a variety of cardiac conditions, because of its ability to improve blood flow by widening the blood vessels.

It can also prevent the heart muscles from thickening and early-stage heart failure, according to research, and sildenafil is already being used to treat pulmonary hypertension; a rare form of high pressure in the blood vessels that supply the lungs.

Prof Tim Chico, professor of cardiovascular medicine and honorary consultant cardiologist at the University of Sheffield, explains: “Viagra was actually first developed as a treatment for problems such as high blood pressure, not for its effects on erectile problems. Viagra has the potential to increase blood supply to a number of different tissues. This is why it may help problems associated with constricted blood vessels such as pulmonary hypertension and there have been reports of using it to treat Raynaud’s phenomenon which is caused by constriction of the arteries in the hands and feet.”

In 2016, a study of patients with diabetes showed that incidental use of Viagra was linked with reduced heart attack risk and improved heart attack survival.

More recently, animal research using the Viagra-like compound Cilalis showed that it could even reverse the signs of heart failure.

“It improved contraction and reversed the adverse structural changes,” says cardiac physiologist Professor Andrew Trafford, from The University of Manchester, lead author on the study.

Viagra could even help mountain climbers battling altitude sickness breathe easier.  

Researchers testing climbers scaling Mount Everest found the drug can open up the tiny veins and arteries in the lungs of climbers in the same way that it increases blood flow to the penis, boosting exercise capacity.

German scientists showed that sildenafil allowed 14 experienced Swiss and German climbers to cope with hypoxia, or lack of oxygen while scaling the world’s highest peak.

Yet while it seems like Viagra could be something of  a wonder drug, experts caution against rushing out to load up on the little blue pills in the hope of reducing Alzheimer’s risk or for wider health benefits.

“While these data are interesting scientifically, based on this study, I would not rush out to start taking sildenafil as a prevention for Alzheimer’s disease,” says Prof Tara Spires-Jones, deputy director of the Centre for Discovery Brain Sciences, University of Edinburgh.

It can be dangerous to take sildenafil for those taking nitrates, which are often prescribed for chest pain and experts warn against taking Viagra if you have recently had a heart attack or stroke, or suffer from low blood pressure.

“Viagra does have possible side effects, most of which relate to its effects on blood vessels such as low blood pressure and flushing. There have been examples of heart attacks after taking Viagra so some patients with angina are cautioned against using it,” warns Prof Chico.