Introduction to Shingles Vaccine and Dementia
Getting vaccinated against shingles — a painful and debilitating condition that can flare up years after infection from varicella zoster — not only lowers the risk of infection, but may also offer some protection against dementia, a provocative new study suggests.
New Research Findings
The new research, published Wednesday in Nature, analyzed data from more than 280,000 older adults in Wales and found that people who received the original shingles live virus vaccine were 20% less likely to develop dementia of any type than those who were not vaccinated.
Previous Research and Study Design
Previous research has found an association between the Shingrix shingles vaccine, which replaced the live virus version in 2020, and a lower risk of dementia, especially in women. But that link wasn’t considered as strong because that study design couldn’t account for potential differences between those who were vaccinated and those who were not, such as the possibility that the vaccinated people might have been healthier overall. Shingrex, which targets a tiny bit of viral DNA, turned out to have a longer lasting effect than the original vaccine.
Unique Public Health Policy in Wales
The new study was possible because of an unusual public health policy in Wales that provided a “natural experiment” to explore the potential impact of the vaccine on dementia risk. With the rollout of the vaccine in 2013 in Wales, shots were offered to people born on or after Sept. 2, 1933, but not those who were born before that date.
Comparison of Vaccinated and Unvaccinated Groups
That allowed the German and Stanford University researchers to compare two groups of people with similar health characteristics who differed only by one week in age, making them essentially the same except that the vaccine was available to the younger population but not the older, said Dr. Pascal Geldsetzer, an assistant professor of medicine at Stanford University and senior author of the study.
Study Design and Findings
What’s exciting about the study is that it’s essentially like a randomized controlled trial, considered the gold standard in research, he said. The way the original vaccine was rolled out in Wales provided a unique opportunity, said Allison Aiello, a professor of epidemiology at the Columbia University Aging Center in New York City.
Expert Insights
“It’s like having a control group compared to a treated group,” said Aiello, who was not associated with the new research. “What’s interesting is the finding of 20% protection. That is a pretty strong effect, which does fit with other research suggesting that herpes viruses might have an influence on dementia.”
Herpes Viruses and Dementia
Scientists don’t know exactly how the chickenpox virus raises the risk of dementia. It’s been shown that reactivation of the virus can lead to the accumulation of aberrant proteins associated with Alzheimer’s, for example, Geldsetzer said. It’s also possible that the virus might spark a reactivation of herpes simplex, which earlier research has linked to dementia.
Shingles Vaccine and Age Effect
Herpes viruses never completely go away, but instead lurk in the body until the immune system weakens. Aging leads to a natural weakening of the immune system that can allow the virus to resurface as shingles, a nasty side effect of chickenpox. The age effect is why the shingles vaccine has been offered only to people age 50 and older in the U.S. It’s given as two doses, two to six months apart.
Herpes Simplex and Central Nervous System
Herpes viruses, including oral and genital herpes simplex, appear to have the ability to get into the central nervous system, experts said. In fact, a 2024 study found that among 70-year-olds without dementia at the outset, older adults with a herpes simplex diagnosis were more than twice as likely as uninfected people to develop dementia over a 15-year follow-up.
Study Findings and Implications
Bolstering the case for the shingles vaccine protecting against dementia were the findings from a study published in Nature Medicine in 2024 that analyzed medical records from more than 100,000 patients. That analysis suggested the newer shingles vaccine was associated with even better protection against dementia. In that study, researchers also investigated whether two other vaccines — for influenza and tetanus, diphtheria and pertussis — had any impact on the risk for dementia. They did not.
Expert Opinions and Take-Home Message
The most important take-home message from the Stanford study is that getting vaccinated might lower the risk for dementia, said Dr. Aarati Didwania, a professor of medicine and medical education at Northwestern University’s Feinberg School of Medicine in Chicago. Exactly how the vaccines might protect against dementia isn’t clear, Didwania said. “But it’s an intriguing question,” she added. “Is it by decreasing inflammation or preventing the virus from reactivating?”
Limitations and Future Directions
There are limitations to the new study. While it indicates the benefit of the vaccine in a real-world setting, it’s not the same as a randomized controlled trial, said Dr. William Schaffner, a professor of infectious diseases at the Vanderbilt University Medical Center in Nashville, Tennessee. But it wouldn’t be ethical to randomly assign people to get the vaccine or not, he said.
Conclusion
In conclusion, the new study suggests that the shingles vaccine may offer some protection against dementia, with a 20% lower risk of developing dementia among vaccinated individuals. While the exact mechanism of this protection is unclear, the findings are promising and warrant further research. The study’s results may also encourage more people to get vaccinated against shingles, which can have a significant impact on public health.
FAQs
Q: What is the shingles vaccine, and how does it work?
A: The shingles vaccine is a vaccine that protects against shingles, a painful and debilitating condition caused by the reactivation of the varicella-zoster virus. The vaccine works by boosting the immune system to prevent the virus from reactivating.
Q: Can the shingles vaccine protect against dementia?
A: The new study suggests that the shingles vaccine may offer some protection against dementia, with a 20% lower risk of developing dementia among vaccinated individuals.
Q: How is the shingles vaccine administered, and who is eligible to receive it?
A: The shingles vaccine is given as two doses, two to six months apart, and is recommended for people aged 50 and older.
Q: What are the potential side effects of the shingles vaccine?
A: Common side effects of the shingles vaccine include redness, swelling, and pain at the injection site, as well as headache and fatigue.
Q: Can I get the shingles vaccine if I have already had shingles?
A: Yes, you can still get the shingles vaccine even if you have already had shingles. The vaccine can help prevent future episodes of shingles.
