Shingles Vaccine May Help Protect Against Dementia
A growing body of research suggests the shingles vaccine may do more than prevent a painful rash — it may also help protect the aging brain.
Exactly how isn't fully understood yet, but the pattern across multiple large studies keeps showing up.
What the Newest Study Found
A study published June 16 in the Annals of Internal Medicine found that nursing facility patients who received at least one dose of the shingles vaccine within a year of admission had a 5.8% lower risk of developing dementia over the following four years.
The findings, drawn from health records of more than 509,000 people aged 66 and older admitted to U.S. nursing facilities between 2017 and 2022, suggest as many as 1 in 17 dementia cases could potentially be prevented through vaccination.
"That's huge," said Kaley Hayes, the study's lead author and associate director of pharmacoepidemiology at Brown University School of Public Health, who said she was surprised by how robust the protection appeared.
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Why the Pattern Keeps Repeating Internationally
This isn't an isolated American finding. Similar results have turned up across multiple countries using very different study designs.
A study of more than 282,000 older adults in Wales, published last year in Nature, found shingles vaccination was associated with a 3.5% reduced dementia risk over seven years. A study of over 101,000 Australians, published in the Journal of the American Medical Association, linked vaccine eligibility to a 1.8% reduced risk over 7.4 years, while a Canadian study of more than 232,000 adults found a 2% reduction over 5.5 years.
The Canadian and Australian studies were specifically designed to sidestep a common bias problem: rather than comparing people who chose to get vaccinated, researchers compared people based on whether they were simply eligible by birth date, regardless of whether they actually got the shot.
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Why Shingles and Dementia Might Actually Be Connected
The leading theory centers on what shingles does to the brain when the virus reactivates, not just the skin.
Shingles can cause a "war zone" of inflammation in the brain, said Dr. Jennifer Pauldurai, medical director of the Inova Brain Health and Memory Disorders Program in northern Virginia, in remarks to NBC News. "When the brain is stressed or challenged with any kind of illness, underlying risks for dementia become more apparent," she said.
Dr. Timothy Chang, an assistant professor of neurology at UCLA's Mary S. Easton Center for Alzheimer's Research and Care, said reactivated shingles virus may trigger buildup of amyloid and tau, the proteins associated with Alzheimer's disease. He also theorized the vaccine could help by boosting overall immune function, reducing neuroinflammation more broadly rather than only blocking the virus itself.
Shingles has also been tied to increased stroke and heart disease risk, said Hayes, offering yet another path by which it could damage brain health — even small, repeated vascular damage from the virus could affect long-term cognitive function.
A Meaningful Difference Between Men and Women
Not everyone appears to benefit from the vaccine's protective effect equally, and the gap shows up consistently across different studies.
In Hayes' research, the link between vaccination and reduced dementia risk was notably weaker among men. The Wales study found the same pattern, with a stronger protective association in women than men — a difference researchers believe may reflect how differently men and women's immune systems respond to vaccination and develop dementia in the first place.
Ann Philbrick, a professor at the University of Minnesota College of Pharmacy, called it promising that the newer Shingrix vaccine appears to offer comparable protection to the older, discontinued Zostavax shot that much of the earlier research focused on.
Why So Few Eligible People Have Actually Gotten It
For Philbrick, the most surprising part of the new study wasn't the dementia link. It was how few people who could benefit from it have actually received the vaccine.
Fewer than 2% of vaccine-eligible nursing facility patients in Hayes' study — a population whose health was already vulnerable — had received even one dose. More broadly, only about a third of U.S. adults 50 and older, and 43.8% of those 60 and older, had received at least one dose of either shingles vaccine as of 2022, with lower rates among Black and Hispanic adults than white adults.
Cost isn't the main barrier, since Shingrix is typically covered by Medicare Part D, Medicaid, and most commercial insurance. The bigger obstacle is logistical: it requires scheduling an appointment, then a follow-up for the second of two required doses.
Key Takeaways
- A study of over 509,000 nursing facility patients found the shingles vaccine was linked to a 5.8% lower dementia risk over four years.
- Similar protective effects have been found in Wales, Australia, and Canada, with reductions ranging from 1.8% to 3.5%.
- Researchers believe shingles-related brain inflammation and buildup of Alzheimer's-linked proteins may explain the connection.
- The protective effect appears weaker in men than in women across multiple studies.
- Fewer than 2% of eligible nursing facility patients, and only about a third of US adults 50+, have received the vaccine.
