Older adults who received the recombinant shingles vaccine were 24 percent less likely to be diagnosed with dementia within four years, according to a large observational study published in Annals of Internal Medicine.
Researchers at Brown University estimate that about one in 17 dementia cases in this population could potentially be prevented by vaccination.
The team used Medicare claims and electronic health records from 509,926 adults aged 66 and older who entered more than 5,500 skilled nursing facilities between 2017 and 2022.
Dementia developed in 18.8 percent of vaccinated participants compared with 24.6 percent of the unvaccinated over the four-year follow-up.
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What the study actually shows
The researchers used a technique called target trial emulation, which is designed to make observational data behave more like a randomized clinical trial.
Only 8,843 of the more than half a million participants had received the recombinant shingles vaccine, sold as Shingrix and introduced in the United States in 2017.
Lead author Kaley Hayes, an assistant professor at Brown University's School of Public Health, said the estimated benefit translates to "about one in 17 dementia cases potentially being prevented."
The study cannot prove that Shingrix itself caused the lower dementia rate.
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People who accepted the vaccine tended to be slightly younger and healthier than those who did not, and although the team adjusted for those differences, they could not fully account for the association.
Randomized clinical trials would be needed to confirm a causal link.
Why a shingles shot might protect the brain
Shingles is caused by reactivation of the varicella-zoster virus, the same virus behind chickenpox, which lies dormant in nerve tissue after childhood infection.
A 2025 review in Nature Medicine described how varicella-zoster reactivation can lead to long-lasting cognitive impairment through vasculopathy, amyloid deposition and neuroinflammation.
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If preventing shingles also blunts these downstream effects, the vaccine could plausibly lower dementia risk as a side benefit.
What it means if you are 50 or older
Shingrix is currently the only shingles vaccine available in the United States.
The Centers for Disease Control and Prevention recommends two doses separated by two to six months for immunocompetent adults aged 50 and older, whether or not they recall a previous case of shingles.
The vaccine is also recommended for adults 19 and older who are immunocompromised.
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The dementia finding sits alongside earlier research linking Shingrix to a lower risk of other conditions in older adults, and it adds a second reason to consider vaccination beyond preventing the painful rash and nerve complications that shingles itself can cause.
Anyone weighing the shot can ask a primary care doctor or pharmacist whether they are up to date.
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This article is made and published by Mie Hermansen, who may have used AI in the preparation.