Alzheimer’s disease is one of the most feared illnesses of old age. It slowly damages memory, thinking ability, and everyday functioning.
Over time, people with Alzheimer’s may struggle to recognize loved ones, manage daily tasks, or remember important events. The disease is the most common form of dementia and affects millions of families around the world.
In the United Kingdom alone, around one million people are currently living with dementia. Experts estimate that one in three people born today could develop dementia during their lifetime. Despite decades of research, scientists still do not have a cure that can stop or reverse Alzheimer’s disease.
Because developing completely new medicines is extremely difficult and expensive, researchers are exploring a different strategy. Instead of creating drugs from scratch, they are examining medicines that are already approved for other diseases to see whether they might also protect the brain. This approach is called drug repurposing.
Drug repurposing can save time and money because these medicines have already been tested for safety. Normally, developing a brand‑new drug can take 10 to 15 years and cost billions of dollars.
Even after all that effort, many drugs fail during testing. If an existing medication already has a good safety record, scientists may be able to move more quickly into clinical trials.
A new study led by researchers at the University of Exeter used this approach to search for possible Alzheimer’s treatments. The research was funded by Alzheimer’s Society and published in the journal Alzheimer’s Research and Therapy.
The project also received support from the National Institute for Health and Care Research and several UK research centres focused on brain health.
To find promising candidates, the research team gathered an international panel of experts. The group included 21 specialists in dementia research from universities, hospitals, and the pharmaceutical industry. Importantly, people affected by dementia also participated in the process, helping researchers consider real-world perspectives.
The panel reviewed 80 different medications that are already used to treat other health conditions. Each drug was carefully evaluated to see whether it might help treat or prevent Alzheimer’s disease.
The scientists considered several factors, including how the drug affects the brain, whether it targets biological processes linked to Alzheimer’s, and whether it has shown encouraging results in laboratory studies.
After several rounds of review and discussion, the panel selected three medications that appeared most promising. These drugs were named “priority candidates” for future research.
The first and most surprising candidate was the shingles vaccine known as Zostavax. Shingles is caused by the same virus responsible for chickenpox. In recent years, scientists have begun exploring whether viral infections might play a role in the development of dementia.
Some studies suggest that the shingles virus may affect the brain and immune system in ways that increase dementia risk.
The vaccine may help prevent these effects by strengthening the immune system and preventing the virus from becoming active again. Previous research has suggested that people who received the shingles vaccine were about 16 percent less likely to develop dementia compared with those who did not receive it.
Because the vaccine already has a long history of safe use and usually requires only one or two doses, researchers believe it could be a practical option if future studies confirm its benefits.
The second promising drug identified in the study was sildenafil, better known by the brand name Viagra. This medication is widely used to treat erectile dysfunction and some circulation problems. Researchers have found that sildenafil may increase blood flow to the brain and help protect nerve cells.
In animal studies, sildenafil appeared to reduce the buildup of tau protein in the brain. Tau is one of the abnormal proteins that accumulates in Alzheimer’s disease and contributes to damage in brain cells. Some experiments in mice also showed improvements in memory and thinking ability after treatment with the drug.
The third candidate was riluzole, a medication currently used to treat motor neurone disease, also known as ALS. Riluzole works by affecting the chemical signals used by nerve cells.
Laboratory studies have shown that the drug may reduce harmful brain activity linked to Alzheimer’s disease. In animal models, riluzole improved cognitive performance and lowered levels of tau protein.
In addition to these three priority drugs, the researchers also considered several other medications that showed some potential. These included fingolimod, vortioxetine, microlithium, dasatinib, and cytisine. However, these drugs did not meet all the criteria needed to be placed among the top candidates for further study.
The scientists emphasize that these findings are only the first step. None of the medications have yet been proven to treat or prevent Alzheimer’s disease in humans. Carefully designed clinical trials will be necessary to determine whether they truly work.
One possible future study may focus on the shingles vaccine. Researchers hope to launch a large clinical trial in the United Kingdom using a research platform called PROTECT. This project allows volunteers to participate in long-term brain health research by completing online questionnaires and cognitive tests each year.
Experts involved in the research say that drug repurposing represents one of the most exciting directions in Alzheimer’s research. In the past, medications such as aspirin were originally developed for one purpose but later found to provide other major health benefits, including reducing the risk of heart attacks and strokes.
The results of this study suggest that existing medicines may also offer unexpected benefits for brain health.
However, it is important to interpret the findings carefully. The current evidence comes mainly from laboratory studies, early clinical data, and expert evaluation rather than large trials involving people with Alzheimer’s disease. This means that the potential benefits remain uncertain.
Even so, the research provides a valuable roadmap for future studies. By focusing on medicines that are already known to be safe, scientists may be able to accelerate the search for treatments that slow or prevent Alzheimer’s disease.
If future clinical trials confirm these early signals, these familiar medicines could become powerful new tools in the fight against one of the world’s most devastating diseases.
If you care about Alzheimer’s, please read studies about the likely cause of Alzheimer’s disease, and new non-drug treatment that could help prevent Alzheimer’s.
For more health information, please see recent studies about diet that may help prevent Alzheimer’s, and results showing some dementia cases could be prevented by changing these 12 things.
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