One of the most intriguing developments in dementia prevention over the past two years has nothing to do with a new Alzheimer’s drug. It concerns a vaccine that millions of adults are already eligible for: the shingles vaccine. A series of large studies has found that people who receive it go on to develop dementia less often than those who do not — and the size of the effect has surprised even the researchers who found it.

This is a genuinely interesting finding, and one worth understanding clearly, because it sits at the intersection of two things I care about: preventing dementia, and separating real signal from hype.

What the Studies Found

The most rigorous evidence comes from a 2025 study in Nature that took advantage of a natural experiment in Wales. When the shingles vaccine was rolled out there, eligibility was determined by an exact date of birth cutoff: people born just before a certain date were ineligible, and those born just after were eligible. Because that cutoff is essentially arbitrary, it created two groups that were nearly identical except for their access to the vaccine — the closest thing to a randomized trial that observational data can offer.

The result: those who were eligible for and received the vaccine were significantly less likely to be diagnosed with dementia over the following seven years. A separate 2024 study in Nature Medicine, examining the newer recombinant vaccine (Shingrix), found a similar protective association, with vaccinated individuals experiencing a longer dementia-free period.

Key Point

The Welsh natural experiment is important because its design mimics randomization. That makes it much harder to dismiss the shingles-dementia link as a statistical artifact of healthier people simply being more likely to get vaccinated.

Why Would a Shingles Vaccine Affect the Brain?

There are two leading explanations, and again, they may both be partly true.

The first is specific to the virus. Shingles is caused by reactivation of the varicella-zoster virus, a member of the herpesvirus family. There is a long-standing hypothesis that herpesviruses contribute to Alzheimer’s pathology — that latent viral reactivation in the nervous system drives inflammation and amyloid deposition over time. By preventing reactivation, the vaccine might interrupt that process.

The second is more general. The newer recombinant vaccine contains an adjuvant that broadly stimulates the immune system, and some of the protective signal has been seen with other adjuvanted vaccines as well. This raises the possibility that part of the benefit comes from training the immune system in a way that is protective for the aging brain, not solely from blocking one specific virus.

“We do not yet know the mechanism with certainty. But we do not need to fully understand why a well-tolerated, already-recommended vaccine helps in order to recommend it — the case for getting it was already strong.”

What This Means for You

Here is the practical part, and it is refreshingly simple. The shingles vaccine is already recommended for essentially all adults aged 50 and older, and for some younger immunocompromised adults, specifically to prevent shingles and its complications — which include a debilitating chronic pain syndrome. That recommendation stands entirely on its own merits.

The emerging dementia data is best understood as a substantial potential bonus, not as a reason to think of the vaccine as an anti-Alzheimer’s treatment. If you are eligible and have not been vaccinated, this is one more good reason to do so. If you have already received it, there is nothing further to do on that front.

A few important caveats. This research does not prove the vaccine prevents dementia; even the natural-experiment design falls short of a purpose-built randomized trial, which is now underway. And the vaccine is not a substitute for the broader work of brain health — it is one modifiable factor among many.

The Bigger Picture

What I find most valuable about this line of research is how it expands our sense of what “dementia prevention” includes. We tend to focus on the familiar levers — blood pressure, exercise, sleep, hearing. The shingles-vaccine story is a reminder that infection and inflammation belong on that list too, and that it is worth accounting for the full range of the 45% of dementia risk that is potentially modifiable. In my practice, staying current on recommended vaccinations is a routine part of a comprehensive brain health assessment, alongside the metabolic, vascular, and lifestyle factors that get more of the attention.

References

  1. Eyting M, Xie M, Michalik F, et al. A natural experiment on the effect of herpes zoster vaccination on dementia. Nature. 2025;641(8062):438-446. doi:10.1038/s41586-025-08800-x
  2. Taquet M, Dercon Q, Todd JA, Harrison PJ. The recombinant shingles vaccine is associated with lower risk of dementia. Nat Med. 2024;30(10):2777-2781. doi:10.1038/s41591-024-03201-5
  3. Livingston G, Huntley J, Liu KY, et al. Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. The Lancet. 2024;404(10452):572-628. doi:10.1016/S0140-6736(24)01296-0

Published July 2026 · Medically reviewed by Nadir Bilici, MD, DipIBLM. See our editorial policy.