A recent study, backed by the Alzheimer's Society and conducted by the University of Exeter, has revealed promising findings in the fight against Alzheimer's disease. The research, published in Alzheimer's Research and Therapy, highlights a shingles vaccine (Zostavax) as a leading candidate among the drugs examined. Additionally, Viagra (sildenafil) and riluzole, a medication for motor neurone disease, have also demonstrated significant potential.
The Importance of Drug Repurposing
Dementia remains the top cause of death in the UK, impacting nearly one million individuals. Current statistics suggest that one in three people born today will eventually develop some form of dementia, yet effective treatments are still lacking.
Developing new medications can take a decade or longer and often costs billions, with no assurance of success. In contrast, repurposing existing, approved medications could provide a quicker, safer, and more cost-effective route to discovering new treatments for Alzheimer's.
This research was also supported by the National Institute for Health and Care Research (NIHR), the Exeter Biomedical Research Centre, and the NIHR HealthTech Research Centre focused on Brain Health.
Selecting the Leading Candidates for Alzheimer's Treatment
A team of 21 international dementia experts, including professionals from universities, hospitals, and the pharmaceutical sector, as well as individuals affected by dementia, evaluated 80 existing medications. Their objective was to pinpoint which drugs showed the most promise for treating or preventing Alzheimer's disease, which constitutes over half of all dementia cases.
Following extensive reviews, the panel identified three 'priority candidates' for further investigation. Each was selected based on its ability to target biological processes associated with Alzheimer's, show positive results in preliminary studies, and be deemed safe for older adults.
The three priority drugs are:
- Shingles vaccine (Zostavax) - Research indicates a possible link between the shingles virus and dementia. The vaccine may help mitigate harmful immune changes associated with Alzheimer's.
- Sildenafil (Viagra) - Studies suggest it may protect nerve cells and reduce the accumulation of tau, a protein linked to Alzheimer's. In animal research, sildenafil also enhanced cognitive functions, potentially by increasing cerebral blood flow.
- Riluzole - Currently used for motor neurone disease, riluzole has shown to enhance cognitive abilities and decrease tau levels in animal studies.
Shingles Vaccine Shows the Most Promise
Experts are advocating for clinical trials to assess the efficacy of these medications for individuals with Alzheimer's or those at risk. Among the candidates, the shingles vaccine is particularly noteworthy due to its safety profile and the fact that it requires only two doses. Prior studies suggest that individuals who received the vaccine were approximately 16% less likely to develop dementia.
Researchers are planning a large-scale clinical trial in the UK for the shingles vaccine, utilizing the PROTECT online registry, where volunteers can share their health and lifestyle information while participating in brain health studies.
Other Medications Evaluated
Five additional drugs were considered but did not qualify as 'priority candidates.' These included fingolimod (for MS), vortioxetine (for major depressive disorder), microlithium (for depression), dasatinib (for leukemia), and cytisine (used in anesthetics).
Experts Call for Caution and Further Research
Dr. Anne Corbett, a Professor of Dementia Research at the University of Exeter, emphasized the need for comprehensive research efforts: "Combating dementia will require exploring every possible avenue, from leveraging existing medications to discovering new treatments."
"Drug repurposing is a crucial component of this strategy, transforming current medications for one ailment into potential therapies for another."
Prof. Fiona Carragher, Chief Policy and Research Officer at the Alzheimer's Society, added, "Dementia profoundly impacts lives, but we believe that research will ultimately prevail."
"Historically, we have seen medications like aspirin repurposed from pain relief to reducing heart attack risks. We aspire to achieve similar breakthroughs in dementia treatment through drug repurposing."