Research published earlier this year found that the shingles vaccine could help prevent dementia in older adults, reducing their odds of developing this debilitating brain disorder over the following seven years by 20 percent.
A new follow-up study, published today and presented at the Clinical Trials on Alzheimer’s Disease Conference, suggests the shingles vaccine could also help adults already diagnosed with dementia, slowing their rate of cognitive decline and prolonging their lives.
“Our analysis is particularly exciting because it shows that the vaccine doesn’t just have a preventive potential, it also appears to have a therapeutic potential because there’s a significant benefit among those who already have dementia,” says senior study author Pascal Geldsetzer, MD, PhD, an assistant professor of medicine at Stanford Medicine in Palo Alto, California.
Vaccination Cut the Risk of Dementia-Related Death Roughly in Half
For the new research, Dr. Geldsetzer and colleagues referred back to the health records of more than 280,000 older adults (ages 71 to 88) — the same group they followed for their earlier study — treated at primary care clinics in Wales.
The scientists expanded their investigation to include around 7,000 more seniors who had dementia at the start of the vaccination program and then died from dementia during the next nine years.
Including the new group of adults, the data analysis found that vaccination against shingles cut the risk of dementia-related death roughly in half over the follow-up period — about 30 percent of vaccinated adults with dementia died over those nine years, versus about 60 percent of adults with dementia who didn’t get the shingles shot.
The authors additionally note that protection afforded by the shingles vaccine was much more pronounced in women than in men.
“This is really a strong outcome showing a relationship between vaccination and fewer dementia-related deaths,” says Geldsetzer.
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New Diagnoses of Mild Cognitive Impairment Also Declined After Vaccination
The new study also showed that adults who’d gotten the shingles shot were less likely to be diagnosed with mild cognitive impairment during the nine-year follow-up than those who were unvaccinated.
Mild cognitive impairment (MCI) is a neurological condition that can cause noticeable memory and thinking problems, but unlike dementia doesn’t usually interfere with daily life. Among those who have MCI, many will go on to develop dementia.
In this study, about 20,700 adults were diagnosed with mild cognitive impairment during follow-up. From this, researchers concluded that vaccination led to about a 3 percentage point reduction in new diagnoses of mild cognitive impairment over nine years.
Why Shingles Vaccination May Make a Difference
Serious viral illnesses like shingles can trigger inflammation in the brain, which can lead to brain deterioration and dementia.
“If you have a severe bout of the flu, for instance, that may accelerate a loss of cognitive function,” says Monica Carson, PhD, chair of the biomedical sciences department at the University of California in Riverside, who was not involved in the new study. “So it correlates that if you have a vaccine that can prevent reactivation of a virus [like the one that causes shingles], it may decrease your risk of having Alzheimer’s or other kinds of dementia,” says Dr. Carson, whose research focuses on how genetics and inflammation trigger or exacerbate neurodegenerative disorders.
Similarly, other vaccines may have a protective effect on the brain. A large study published in 2022 that involved more than two million participants, for example, indicated that getting a flu shot was tied to a lower risk of Alzheimer’s disease, the most common cause of dementia.
The stronger protection against dementia that women experienced after vaccination could be due to sex differences in immune response or in the way dementia develops, according to Geldsetzer. Women on average have higher antibody responses to vaccination, for example, and shingles is more common in women than in men.
A Unique Situation Provides Strong Evidence
So far, research suggesting a link between vaccination and lower dementia rates has relied on preexisting health records. But this type of data may suggest an association, not a cause-and-effect relationship. For more conclusive proof, a randomized controlled trial — in which scientists randomly assign participants to a treatment group or a control group — is the gold standard.
But conducting a randomized trial on the association between vaccination and dementia poses many challenges, including the long timeframe required to follow who develops this condition.
A vaccination program in Wales, however, provided a unique situation that was as close to a randomized controlled trial as scientists could get without devising one, according to Geldsetzer.
Because of a program designed to ration vaccine supply, launched on September 1, 2013, anyone age 79 on that date was eligible for a shingles vaccine for one year, while people who were 80 or older would never be eligible. The researchers then examined dementia rates in people who turned 80 the week before September 1 with people who turned 80 the week after.
“We had a vaccine-eligible and a vaccine-ineligible group for which we know that they should be on average similar to each other, and therefore good comparison groups,” Geldsetzer says.
Since beginning this analysis, the Stanford team has found similar vaccination programs in New Zealand, Australia, and Canada, that have produced results mirroring the Wales study.
“We just keep seeing this strong protective signal for dementia in dataset after dataset,” says Geldsetzer.
These Findings Require Follow-Up Research
Based on results so far, the relation between shingles vaccination and dementia deserves more extensive investigation. Results were limited in the study group by only including very old patients, and with proper resources and time, study authors expect they could conduct an actual randomized controlled trial, despite the difficulties involved.
Additionally, while the shingles vaccine in this research appears to have a strong protective effect, the authors acknowledge that the shingles vaccine in the United States is different from the one in their study.
The only brand of shingles vaccine currently available in the United States is Shingrix, while the vaccine used during this study was Zostavax, which is no longer in use in the United States.
Zostavax contains a weakened form of the live varicella-zoster virus. Shingrix works with an inactivated version of the virus but is considered to be more effective and longer-lasting than Zostavax.
Other recent research suggests that Shingrix offers similar benefits to Zostavax regarding reduction in dementia risk.
While outcomes with the Shingrix vaccine may be different and further research is warranted, there is good reason to think that results with Shingrix could be even better than with Zostavax.
“Shingrix may be more effective against dementia because it’s the more effective vaccine for preventing shingles,” Carson says. “More inflammation is associated with increased risk, so there is a common sense to this.”
Preventing Shingles Is Reason Enough to Get the Shingles Vaccine
Shingles is a viral infection that produces a painful rash and can cause complications such as lingering nerve pain, vision problems (which can become permanent), and other rare but serious health issues.
Shingles is caused by the same virus that causes chicken pox, varicella zoster. After people contract chicken pox, usually in childhood, the virus stays dormant in the nerve cells for life. In people who are older or have weakened immune systems, the dormant virus can reactivate and cause shingles.
Vaccination is more than 90 percent effective at preventing shingles. The Centers for Disease Control and Prevention (CDC) recommends the shingles shot for adults 50 years and older with healthy immune systems, and adults 19 years and older who have weakened immune systems and are at higher risk of complications.
For people who hesitate about getting their shingles vaccine, this reduction in dementia risk provides one more reason to make that choice, according to Geldsetzer.
“There is strong emerging evidence of a cause and effect relationship between shingles vaccination and benefits for the dementia disease process,” he says. “The shingles vaccine is inexpensive compared to other dementia treatments, so this could really have huge implications for clinical care.”
EDITORIAL SOURCES
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Resources
Xie M et al. The Effect of Shingles Vaccination at Different Stages of the Dementia Disease Course. Cell. December 2, 2025.
Could a Viral Illness Increase Chances of Developing Alzheimer’s or Other Neurodegenerative Disease? National Institute on Aging. January 19, 2023.
Bukhbinder A et al. Risk of Alzheimer’s Disease Following Influenza Vaccination: A Claims-Based Cohort Study Using Propensity Score Matching. Journal of Alzheimer’s Disease. 2022.
Gold Standard of Evidence: The Randomized Controlled Trial (RCT). Kennedy Krieger.
Tom Gavin joined Everyday Health as copy chief in 2022 after a lengthy stint as a freelance copy editor. He has a bachelor's degree in psychology from College of the Holy Cross.
Prior to working for Everyday Health, he wrote, edited, copy edited, and fact-checked for books, magazines, and digital content covering a range of topics, including women's health, lifestyle, recipes, restaurant reviews, travel, and more. His clients have included Frommer's, Time-Life, and Google, among others.
He lives in Brooklyn, New York, where he likes to spend his time making music, fixing too-old electronics, and having fun with his family and the dog who has taken up residence in their home.
Don Rauf has been a freelance health writer for over 12 years and his writing has been featured in HealthDay, CBS News, WebMD, U.S. News & World Report, Mental Floss, United Press International (UPI), Health, and MedicineNet. He was previously a reporter for DailyRx.com where he covered stories related to cardiology, diabetes, lung cancer, prostate cancer, erectile dysfunction, menopause, and allergies. He has interviewed doctors and pharmaceutical representatives in the U.S. and abroad.
He is a prolific writer and has written more than 50 books, including Lost America: Vanished Civilizations, Abandoned Towns, and Roadside Attractions. Rauf lives in Seattle, Washington.
