An unusual public health policy in Wales has offered compelling evidence that the shingles vaccine could reduce dementia risk.
A Stanford Medicine-led study found that Welsh older adults who received the shingles vaccine were 20% less likely to develop dementia over the following seven years than those who didn’t receive it.
Published in Nature on April 2, the findings support the idea that certain viral infections—especially those affecting the nervous system—may increase the risk of dementia. If confirmed by further research, the results suggest that a widely available vaccine could serve as a preventive measure against dementia.
In a follow-up study, published Dec. 2 in Cell, researchers found that the vaccine may also benefit people already diagnosed with dementia by slowing disease progression.
Shingles, caused by the varicella-zoster virus (the same virus responsible for chickenpox), can reactivate in older adults, leading to painful rashes. This virus remains dormant in nerve cells and can become active when immunity wanes.
With over 55 million people affected globally by dementia, the possibility of prevention via a common vaccine is an important breakthrough.
Dr. Pascal Geldsetzer, senior author of the study and assistant professor of medicine at Stanford, noted that past studies linking the shingles vaccine and reduced dementia risk may be flawed due to bias: people who choose to get vaccinated may also engage in other healthy behaviors.
However, Wales’ shingles vaccination policy provided a rare natural experiment. Launched on Sept. 1, 2013, the program made only those aged 79 on that date eligible for a one-year vaccination window. Those 80 or older were permanently ineligible. Researchers compared people who turned 80 just before the cutoff to those who turned 80 just after.
Analyzing health records of 280,000 Welsh adults aged 71 to 88, researchers found no major differences in lifestyle or health characteristics between the groups—except access to the vaccine. This allowed for a more reliable comparison than typical observational studies.
Among the key findings: the vaccine reduced shingles cases by 37% and dementia diagnoses by 20% over seven years. Importantly, researchers found no differences in education levels, preventive healthcare use, or incidence of other conditions between the two groups, further strengthening the validity of their results.
The team also discovered that people who had already been diagnosed with dementia and received the vaccine were 30% less likely to die from dementia-related causes in the following nine years, compared to a 50% death rate among those unvaccinated. This indicates the vaccine might slow disease progression.
Interestingly, the protective effect was more pronounced in women, potentially due to sex-based differences in immune response or how dementia develops. Women generally have stronger vaccine responses and are more prone to shingles.
Researchers are still unsure of the exact biological mechanism behind the vaccine’s protective effects. It may be due to reduced viral reactivation or broader immune system activation.
These findings have been replicated in datasets from several other countries, including England, Australia, New Zealand, and Canada. Dr. Geldsetzer now aims to launch a large randomized controlled trial to definitively confirm these results. He is seeking philanthropic funding to support the trial, as the live-attenuated vaccine is no longer under patent.
If successful, this research could pave the way for a simple, cost-effective, and widely available intervention to help prevent or slow dementia.
If you care about brain health, please read studies about Vitamin B9 deficiency linked to higher dementia risk, and cranberries could help boost memory.
For more health information, please see recent studies about heartburn drugs that could increase risk of dementia, and results showing this MIND diet may protect your cognitive function, prevent dementia.
Copyright © 2025 Knowridge Science Report. All rights reserved.
