Viagra, a drug widely prescribed for erectile dysfunction, may also help protect the brain against Alzheimer’s disease, according to new research that points to the growing potential of drug repurposing in dementia care.
The study was funded by the Alzheimer’s Society and led by researchers at the University of Exeter. The findings were published in the journal Alzheimer’s Research & Therapy. Instead of developing new medicines from the ground up, scientists examined drugs already approved for other conditions, aiming to shorten the path to effective Alzheimer’s treatments.
Dementia burden continues to grow
Dementia remains the leading cause of death in the United Kingdom and affects around one million people. Alzheimer’s disease accounts for more than half of all dementia diagnoses. Experts estimate that one in three people born today will develop dementia during their lifetime.
Despite years of research, there is still no cure. Developing a new drug can take 10 to 15 years and cost billions of pounds, with many candidates failing before reaching patients. Researchers say this has increased interest in repurposing medicines that already have proven safety records.
International experts review 80 medicines
To identify the most promising candidates, an international panel of 21 dementia specialists reviewed 80 existing medications. The group included experts from universities, hospitals, and the pharmaceutical industry, as well as people affected by dementia and their families.
After several rounds of evaluation, the panel agreed on three “priority candidates” for further research. Each drug targets biological processes linked to Alzheimer’s, has shown encouraging results in laboratory and animal studies, and is considered safe for use in older adults.
Viagra may do more than treat erectile dysfunction.
New research finds sildenafil could help protect the brain against Alzheimer’s by reducing toxic tau buildup and improving blood flow. Experts say it’s one of three existing medicines now showing promise in dementia research. pic.twitter.com/4FMVgOehPI
— Tom Marvolo Riddle (@tom_riddle2025) February 19, 2026
Why did sildenafil draw attention
Sildenafil, commonly known by the brand name Viagra, emerged as one of the strongest candidates. Research suggests the drug may protect nerve cells and reduce the buildup of tau, a protein that accumulates abnormally in Alzheimer’s disease and damages brain function.
Animal studies found that sildenafil improved memory and learning. Researchers believe this effect may be linked to increased blood flow in the brain, which supports healthier brain activity and may slow cognitive decline.
Vaccine and neurological drug are also shortlisted
The shingles vaccine Zostavax was identified as the most promising of the three candidates. Previous studies suggest a possible link between shingles infection and dementia risk. Scientists also know that immune system changes play a role in Alzheimer’s.
The vaccine interacts with immune responses in a way that may help reduce harmful brain processes. Some studies have found that people who received the vaccine were about 16% less likely to develop dementia.
The third shortlisted drug was riluzole, which is currently prescribed for motor neurone disease. In animal studies, riluzole improved cognitive performance and lowered tau levels, suggesting it could help slow brain damage associated with Alzheimer’s.
Calls grow for large clinical trials
Researchers stress that laboratory and animal findings are only an early step. Clinical trials are now needed to determine whether these drugs truly benefit people with Alzheimer’s or those at risk of developing the disease.
Scientists hope to launch a large UK clinical trial focusing on the shingles vaccine, using data from PROTECT. The online platform allows volunteers to complete annual health questionnaires and cognitive tests from home, helping researchers track brain health over time while reducing costs and speeding recruitment.
The study also received support from the National Institute for Health and Care Research, the Exeter Biomedical Research Centre, and the NIHR HealthTech Research Centre in Brain Health.
Experts urge caution despite promise
Dr. Anne Corbett, a professor of dementia research at the University of Exeter, said beating dementia will require progress on many fronts, including making better use of existing medicines. She stressed that none of the identified drugs can yet be considered proven treatments and that robust clinical trials are essential.
Prof. Fiona Carragher, chief policy and research officer at the Alzheimer’s Society, said drug repurposing has already transformed care in other areas of medicine. She pointed to aspirin, once used only as a painkiller, later shown to reduce the risk of heart attacks and strokes. Researchers now hope similar breakthroughs could reshape Alzheimer’s care.
Experts say the next phase of research will determine whether Viagra’s unexpected effects can translate into real protection for the ageing brain.
