A shingles shot may do more than prevent rash — it could help shield the aging brain from dementia, according to a landmark study using real-world data from the UK.
A routine vaccine could offer more than protection from varicella-zoster virus — it could help delay or prevent dementia, according to a robust natural experiment conducted by Stanford researchers and published in the journal Nature. In a recent study, a research team at Stanford University reported that the herpes zoster (shingles) vaccine may lower the risk of developing dementia, offering a potential new tool in the fight against cognitive decline.
Link between herpesviruses and dementia
For years, scientists have explored potential links between neurotropic herpesviruses and dementia. Some evidence suggests that infections caused by these viruses may contribute to neurodegeneration. While vaccination is commonly used to prevent infections, emerging research indicates that vaccines, especially live-attenuated ones, can have broader effects on the immune system, sometimes influencing conditions unrelated to the targeted disease.
However, previous studies examining the relationship between vaccines and dementia have struggled with a key challenge — distinguishing correlation from causation. Many have simply compared dementia rates between vaccinated and unvaccinated individuals, but this approach is prone to bias. Furthermore, factors such as personal health awareness, access to healthcare, and even cognitive ability can influence whether someone gets vaccinated, making it difficult to isolate the true effect of the vaccine.
About the study
In the present study, the researchers utilized the vaccine eligibility rules in Wales, United Kingdom (U.K.), to evaluate the impact of the herpes zoster vaccine on dementia risk. In the U.K., the eligibility for the herpes zoster vaccine was determined solely by birth date. Those born on or after September 2, 1933, were eligible to receive the vaccine, while those born just before this date were not.
This provided the researchers with a unique opportunity to study the vaccine’s effect on dementia risk, as individuals born just a few weeks apart are unlikely to differ in any meaningful way in other aspects of life, except for their access to the vaccine. This rare policy feature enabled researchers to apply a regression discontinuity design, simulating a natural experiment that is highly resistant to confounding. The authors also confirmed their findings using a difference-in-differences instrumental variable (DID-IV) approach, further reinforcing the robustness of their causal claims.
By analyzing large-scale electronic health records, the researchers could compare the long-term dementia risk between these two groups while minimizing confounding factors. The findings were corroborated in a secondary analysis of dementia-related deaths across England and Wales, further strengthening the causal inference. The study used regression discontinuity design, a statistical technique for determining causal relationships, and analyzed data from a seven-year follow-up period.
Major findings
The study found that receiving the herpes zoster vaccine was associated with a 3.5 percentage point reduction in dementia diagnoses over seven years, which translates to a 20% relative decrease. This estimate accounts for the fact that not all individuals who were eligible actually received the vaccine. The protective effect was stronger in women, reaching statistical significance, while the findings in men were inconclusive due to wider confidence intervals.
To confirm their findings, the researchers conducted a separate analysis using death certificate data. This secondary analysis supported their initial conclusions, showing that eligibility for the herpes zoster vaccine reduced dementia-related deaths by approximately 5% over nine years.
Beyond dementia, the study also confirmed that the vaccine significantly reduced the occurrence of shingles, consistent with clinical trial data. However, the observed reduction in dementia risk could not be fully explained by a decrease in shingles cases alone, suggesting that other mechanisms might be at play. Notably, the reduction in dementia incidence only became evident more than one year post-vaccination, supporting theories of long-term immune modulation.
The researchers explored several potential explanations for the vaccine’s apparent protective effect. One hypothesis was that the vaccine helps suppress reactivations of the varicella-zoster virus, which causes shingles. Some studies have suggested that such viral reactivations may contribute to neuroinflammation, a key factor in dementia development.
Another potential mechanism suggested a broader immune-modulating effect of the vaccine. Live-attenuated vaccines, like the herpes zoster vaccine, can stimulate the immune system in ways that extend beyond their primary target. This immune boost may help the body combat other infections or neuroinflammatory processes linked to dementia, potentially via mechanisms such as trained immunity or heterologous adaptive immunity. The study also explored how prior influenza vaccination and autoimmune conditions may modify the vaccine’s effect, supporting the hypothesis that broader immune modulation could contribute to dementia protection.
While these findings are compelling, the researchers acknowledged several limitations. One challenge was the potential under-detection of dementia in health records, as not all cases are formally diagnosed. The study also focused on a specific age group, making it difficult to apply the results to younger populations.
Another important consideration was that the study examined only the live-attenuated herpes zoster vaccine. Importantly, the study focused on the live-attenuated vaccine Zostavax, as the recombinant vaccine Shingrix was introduced only after the study period ended. It is unclear whether the newer vaccine would have the same effects on dementia risk.
Implications and conclusions
Dementia remains one of the most pressing public health challenges worldwide, with no cure currently available. If further research confirms that vaccines can reduce the risk of dementia, this could open up new avenues for prevention. If validated in other settings, the shingles vaccine could represent one of the most effective and cost-effective preventive strategies for dementia. Furthermore, given the widespread availability and safety profile of the herpes zoster vaccine, these findings suggest a promising, low-risk intervention that could potentially help millions of people.
While further research is needed to understand the exact mechanisms at play, this study provides compelling evidence that the herpes zoster vaccine may do more than just prevent shingles — it may also help protect the aging brain.
- Eyting, M., Xie, M., Michalik, F. et al. (2025). A natural experiment on the effect of herpes zoster vaccination on dementia. Nature. DOI:10.1038/s41586-025-08800-x https://www.nature.com/articles/s41586-025-08800-x
News
Scientists Melt Cancer’s Hidden “Power Hubs” and Stop Tumor Growth
Researchers discovered that in a rare kidney cancer, RNA builds droplet-like hubs that act as growth control centers inside tumor cells. By engineering a molecular switch to dissolve these hubs, they were able to halt cancer [...]
Platelet-inspired nanoparticles could improve treatment of inflammatory diseases
Scientists have developed platelet-inspired nanoparticles that deliver anti-inflammatory drugs directly to brain-computer interface implants, doubling their effectiveness. Scientists have found a way to improve the performance of brain-computer interface (BCI) electrodes by delivering anti-inflammatory drugs directly [...]
After 150 years, a new chapter in cancer therapy is finally beginning
For decades, researchers have been looking for ways to destroy cancer cells in a targeted manner without further weakening the body. But for many patients whose immune system is severely impaired by chemotherapy or radiation, [...]
Older chemical libraries show promise for fighting resistant strains of COVID-19 virus
SARS‑CoV‑2, the virus that causes COVID-19, continues to mutate, with some newer strains becoming less responsive to current antiviral treatments like Paxlovid. Now, University of California San Diego scientists and an international team of [...]
Lower doses of immunotherapy for skin cancer give better results, study suggests
According to a new study, lower doses of approved immunotherapy for malignant melanoma can give better results against tumors, while reducing side effects. This is reported by researchers at Karolinska Institutet in the Journal of the National [...]
Researchers highlight five pathways through which microplastics can harm the brain
Microplastics could be fueling neurodegenerative diseases like Alzheimer's and Parkinson's, with a new study highlighting five ways microplastics can trigger inflammation and damage in the brain. More than 57 million people live with dementia, [...]
Tiny Metal Nanodots Obliterate Cancer Cells While Largely Sparing Healthy Tissue
Scientists have developed tiny metal-oxide particles that push cancer cells past their stress limits while sparing healthy tissue. An international team led by RMIT University has developed tiny particles called nanodots, crafted from a metallic compound, [...]
Gold Nanoclusters Could Supercharge Quantum Computers
Researchers found that gold “super atoms” can behave like the atoms in top-tier quantum systems—only far easier to scale. These tiny clusters can be customized at the molecular level, offering a powerful, tunable foundation [...]
A single shot of HPV vaccine may be enough to fight cervical cancer, study finds
WASHINGTON -- A single HPV vaccination appears just as effective as two doses at preventing the viral infection that causes cervical cancer, researchers reported Wednesday. HPV, or human papillomavirus, is very common and spread [...]
New technique overcomes technological barrier in 3D brain imaging
Scientists at the Swiss Light Source SLS have succeeded in mapping a piece of brain tissue in 3D at unprecedented resolution using X-rays, non-destructively. The breakthrough overcomes a long-standing technological barrier that had limited [...]
Scientists Uncover Hidden Blood Pattern in Long COVID
Researchers found persistent microclot and NET structures in Long COVID blood that may explain long-lasting symptoms. Researchers examining Long COVID have identified a structural connection between circulating microclots and neutrophil extracellular traps (NETs). The [...]
This Cellular Trick Helps Cancer Spread, but Could Also Stop It
Groups of normal cbiells can sense far into their surroundings, helping explain cancer cell migration. Understanding this ability could lead to new ways to limit tumor spread. The tale of the princess and the [...]
New mRNA therapy targets drug-resistant pneumonia
Bacteria that multiply on surfaces are a major headache in health care when they gain a foothold on, for example, implants or in catheters. Researchers at Chalmers University of Technology in Sweden have found [...]
Current Heart Health Guidelines Are Failing To Catch a Deadly Genetic Killer
New research reveals that standard screening misses most people with a common inherited cholesterol disorder. A Mayo Clinic study reports that current genetic screening guidelines overlook most people who have familial hypercholesterolemia, an inherited disorder that [...]
Scientists Identify the Evolutionary “Purpose” of Consciousness
Summary: Researchers at Ruhr University Bochum explore why consciousness evolved and why different species developed it in distinct ways. By comparing humans with birds, they show that complex awareness may arise through different neural architectures yet [...]
Novel mRNA therapy curbs antibiotic-resistant infections in preclinical lung models
Researchers at the Icahn School of Medicine at Mount Sinai and collaborators have reported early success with a novel mRNA-based therapy designed to combat antibiotic-resistant bacteria. The findings, published in Nature Biotechnology, show that in [...]
