Viagra may lower risk of Alzheimer's in men, finds new study as top doctor hails 'new avenue to prevention'

Alzheimer's disease is the most common type of dementia - a syndrome associated with the ongoing decline of brain functioning.

Dementia is the UK's biggest killer, accounting for more than one in ten of all deaths across the country.

Despite decades of research, a cure or prevention for dementia has yet to be found, but the latest study could help move the dial, says Alzheimer's Research UK.

As the charity explains, the possibility of repurposing drugs already used for other health conditions could help “accelerate progress and open up new avenues to prevent or treat dementia-causing diseases".

What did the researchers find out?

The new study, published in the journal Neurology, saw experts from University College London (UCL) examine the medical records of 269,725 UK men aged 40 and over, with an average age of 59, who were diagnosed with erectile dysfunction between 2000 and 2017.

Men with a previous diagnosis of dementia or cognitive impairment were not included in the analysis.

Just over half (55 percent) had been prescribed a type of medication known as a PDE5I drug, including sildenafil (sold as Viagra), tadalafil (Cialis), vardenafil and avanafil.

Viagra was the first of these treatments and was originally developed to treat high blood pressure and angina.

UCL experts said that previous animal research has found PDE5I drugs (phosphodiesterase type 5 inhibitors) have some “neuroprotective benefits”.

During the follow-up period – an average of 5.1 years – some 1,119 men were diagnosed with Alzheimer’s disease.

Statistical analysis of the data revealed that people who took the drugs were found to have an 18 percent reduced risk of developing Alzheimer’s compared with those who had erectile dysfunction but did not take the drugs.

Those who were issued prescriptions “most frequently” were even less likely to be diagnosed with Alzheimer’s, the authors said.

Lead author Dr Ruth Brauer, from the UCL School of Pharmacy, said: “Although we’re making progress with the new treatments for Alzheimer’s disease that work to clear amyloid plaques in the brain for people with early stages of the disease, we desperately need treatments that can prevent or delay the development of Alzheimer’s disease.

“More research is needed to confirm these findings, learn more about the potential benefits and mechanisms of these drugs and look into the optimal dosage.

“A randomised, controlled trial with both male and female participants is warranted to determine whether these findings would apply to women as well.”

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Commenting on the study, Dr Leah Mursaleen, head of research at Alzheimer’s Research UK, said: “Developing drugs for diseases like Alzheimer’s is a costly process and can take many years.

“Being able to repurpose drugs already licensed for other health conditions could help accelerate progress and open up new avenues to prevent or treat dementia-causing diseases.

“This research looked at medical records of nearly 270,000 men with erectile dysfunction, and found that those prescribed drugs known as PDE5Is – including common brand name Viagra – also appeared to have a lower risk of developing Alzheimer’s.

“While this is an encouraging finding, it doesn’t yet confirm whether these drugs are directly responsible for reducing Alzheimer’s risk, nor whether they can slow or stop the disease.

“Further research – including clinical trials – will be needed to confirm whether these drugs can indeed play a role in preventing or treating Alzheimer’s. Such studies should also uncover whether these drugs might have effects in other groups, such as women, and men without a diagnosis of erectile function. We also need to understand how this evidence might apply to more diverse populations.”

Tara Spires-Jones, president of the British Neuroscience Association and professor at the UK Dementia Research Institute at the University of Edinburgh, said: “This study does not conclusively prove that erectile dysfunction drugs reduce Alzheimer’s risk but provides good evidence that this type of drug is worth further study in future.”

It comes after researchers analysed insurance claims data of 7.23 million Americans and found Viagra users were 69 percent less likely to develop Alzheimer’s over a six-year period than non-users.

As part of the 2021 study, published in the journal Nature Aging, the researchers also examined brain cells from Alzheimer’s patients and found Viagra users had more brain cell growth and slower formation of neurofibrillary tangles in the brain, an early biomarker of Alzheimer’s.