British pharmaceutical giant GSK has launched a pioneering investigation that could potentially transform dementia prevention strategies by examining whether its shingles vaccine, Shingrix, reduces the risk of developing the neurodegenerative disease.
The ambitious four-year project will analyze data from up to 1.4 million NHS patients to determine if the vaccine, which is already available through the NHS, could help combat dementia—a condition that claims approximately 75,000 lives annually in the UK.
Mounting Evidence for Vaccine's Protective Effect
The GSK study aims to confirm growing evidence that Shingrix may reduce dementia risk by up to 27% compared to an older shingles vaccine, Zostervax, which also demonstrated protective effects. This investigation comes at a critical time when effective dementia treatments remain elusive, with existing drugs like lecanemab and donanemab considered not cost-effective for NHS use.
Tony Wood, GSK's chief scientific officer, emphasized the significance of the research: "We hope this will not only answer key questions to help reduce dementia risk but also pave the way for future research."
The timing of the study is particularly advantageous due to the UK's vaccination policy. Since 2023, Shingrix has been offered to everyone turning 65 to protect against the varicella zoster virus, which causes approximately 50,000 shingles cases annually. However, those who turned 65 before September 2023 become eligible only when they turn 70, creating an ideal research scenario with two comparable age groups—one vaccinated and one unvaccinated.
Stanford Study Strengthens the Connection
The GSK investigation follows compelling research from Stanford Medicine published in Nature, which found that Welsh older adults who received the shingles vaccine were 20% less likely to develop dementia over a seven-year period compared to unvaccinated individuals.
This Stanford study took advantage of a unique "natural experiment" in Wales, where vaccination eligibility was strictly age-based. The program, which began in September 2013, made the vaccine available to those who were 79 on that date for one year, while those who were 80 or older remained ineligible.
"What makes the study so powerful is that it's essentially like a randomized trial with a control group—those a little bit too old to be eligible for the vaccine—and an intervention group—those just young enough to be eligible," explained the Stanford researcher.
The researchers analyzed health records of more than 280,000 older adults and found that by 2020, while one in eight had been diagnosed with dementia, those who received the shingles vaccine were 20% less likely to develop the condition.
Potential Mechanisms and Implications
Scientists are still investigating exactly how the shingles vaccine might influence dementia risk. Dr. Sheona Scales, director of research at Alzheimer's Research UK, noted: "It's not yet clear how the shingles vaccine might influence dementia risk, whether through reducing inflammation, boosting overall immune health or other factors. This study could help uncover these mechanisms and provide insights into whether the vaccine may help delay the onset of dementia."
The Stanford study also revealed that protection against dementia was more pronounced in women than men, possibly due to sex differences in immune response or in dementia development pathways.
Expanding Vaccination Coverage
Professor Adam Finn, a member of the UK Government's Joint Committee on Vaccines and Immunisation, indicated there were already plans to extend shingles vaccination to all over-60s. "If there is found to be a dementia-preventing effect, that might make it cost-effective to give the vaccine even earlier," he added.
Currently, two doses of Shingrix are offered to adults who turned 65 after September 1, 2023. Due to supply constraints, those who turned 65 before then become eligible only at age 70.
Future Research Directions
The findings from both the ongoing GSK study and the Stanford research could potentially revolutionize dementia prevention strategies. If confirmed, millions of older adults could benefit from a vaccine already administered through existing healthcare systems.
Dr. Richard Oakley, associate director of research and innovation at Alzheimer's Society, highlighted the unique research opportunity: "The age cut-offs have produced a large cohort of individuals whose data can be analyzed like a clinical trial."
Researchers are now calling for larger randomized controlled trials to provide definitive evidence of the vaccine's protective effect against dementia, potentially opening a new front in the battle against a condition that affects more than 55 million people worldwide.
