I’ve written several times about how the shingles vaccine reduces the risk of dementia and Alzheimer’s disease, but there’s another large study that confirms the link.

If you’re an older adult, you should seriously consider getting the shingles vaccine. The evidence for its effect is becoming overwhelming and conclusive.

This post will examine this new study about the shingles vaccine effect on the risk of dementia and Alzheimer’s disease

All about shingles and the shingles vaccine

Shingles is a complication of chickenpox, caused by the Varicella zoster virus (VZV). The body’s immune system does not eliminate VZV after chickenpox. Once the symptoms of chickenpox disappear, the virus stays in the dorsal root ganglion, a bundle of nerve fibers at the bottom of the spinal column. The virus stays there, hidden from the body’s immune system.

Even though the body developed an immune response to the original zoster virus infection, several years or decades after the initial infection, the adaptive immune response against the virus wanes or disappears. Due to other unknown factors, possibly stress or other infections like COVID-19 or VZV, the virus “moves” along nerve bundles and initiates a secondary infection with much more serious consequences for the individual.

This second VZV infection, called herpes zoster, is more commonly known as shingles. Shingles usually occurs in adults older than 50, although it can occur at any age, even in young adults. 

Even though the same virus causes chickenpox and shingles, shingles was given a different name, herpes zoster, probably because it was originally thought to be caused by a similar, but unrelated virus.

Shingles is an entirely unpredictable disease. It reactivates due to unknown causes. Once shingles appear, they can be painful, depending on the location of the outbreak. It can cause blindness (from herpes zoster ophthalmicus), disfigurement of the infected area, permanent pain (postherpetic neuralgia), and other conditions.

Shingles can be treated with antiviral drugs, but only if the infection is recognized and treated within 24-72 hours, which means the stricken individual must seek treatment quickly.

Post-herpetic neuralgia pain may last for weeks, months, or even years after the blisters have healed – this is not a trivial disease.

Shingles is not a one-time event. After you develop shingles, it may return in months or years, so it is important to be vaccinated even if you have had shingles.

Almost all individuals in the US aged 50 years and older have been infected with VZV (from chickenpox) and are therefore at risk for shingles. There’s a growing body of evidence that herpes viruses, including VZV, may be linked to cognitive decline.

The only way to prevent a shingles infection is to boost the immune system with a vaccine against the zoster virus. The CDC recommends Shingrix (also known as the zoster vaccine, available in the USA), a relatively new, safe, and effective vaccine that prevents shingles. Shingrix has replaced the older shingles vaccine, Zostavax, because Shingrix is much more effective.

There is another way to prevent shingles — never get chickenpox in the first place. Of course, we have a vaccine for that, the chickenpox (or varicella) vaccine.

The CDC recommends the shingles vaccine for individuals 50 years or older. Additionally, the vaccine should be given to individuals 19 years or older with a compromised immune system. Other countries have different recommendations, so check your country’s public health authorities for recommendations.

So let’s be clear about a couple of things. First, you are at risk of shingles only if you have had chickenpox. Second, children who have received the chickenpox vaccine and never had chickenpox will not be at risk for shingles as they age.

Shingles vaccine and dementia study

In a paper published on 28 April 2026 in Alzheimer’s & Dementia, Susan dos Reis, PhD, University of Maryland School of Pharmacy, Baltimore, and co-authors, analyzed 1.5 million Medicare beneficiaries in the USA. This study focused on individuals who received the newer recombinant shingles vaccine, Shingrix. Many previous studies examined the effect of the older vaccine, Zostavax.

The cohort included 502,845 people who received both doses of the recombinant zoster vaccine and 1,005,690 unvaccinated controls. In both groups, 60% of participants were female, 93% were white, and 55% were aged 70 to 79.

Dementia diagnoses were based on claims data. Findings were adjusted for medical comorbidities, prescription medications, healthcare utilization, and certain preventive vaccinations.

Here are the key results of the study:

• Over follow-up periods of 3 years or less, people who received the recombinant shingles vaccine had 33% lower risk of any dementia type, 28% lower risk of Alzheimer’s disease, and 33% lower risk of vascular dementia.
• The incidence of any type of dementia was 10.45 per 1,000 person-years for older adults who received the two-dose shingles vaccine and 15.73 per 1,000 person-years in the unvaccinated group.
• Over more than 3 years of follow-up, researchers observed a 26% lower risk for any dementia type, 17% lower for Alzheimer’s disease, and 34% lower risk for vascular dementia, they added.

The authors concluded:

The data provide consistent evidence of a significantly lower risk of dementia, including Alzheimer’s disease and vascular dementia, following the two-dose recombinant zoster vaccine vaccination. Our findings align with several studies that demonstrate a lower risk of Alzheimer’s disease and vascular dementia following herpes zoster vaccination.

Summary

This new study shows that the shingles vaccine significantly reduces the risk of developing dementia, especially Alzheimer’s disease and vascular dementia.

Just a reminder that this is an observational study, so it shows correlation, not causation. However, the evidence of correlation is prodigious. As we get more evidence, including this study, the causal relationship between the shingles vaccine and lowering the risk of dementia is becoming overwhelming.

I also want to remind the reader that no one believes that the shingles vaccine has any direct effect on the brain to reduce the risk of dementia and Alzheimer’s disease. The vaccine may have some effect on the development of the disease, but more research would be required into that type of effect.

However, it’s more likely that by preventing shingles, a disease that may increase the risk of developing dementia, we reduce the risk.

The most important thing about the shingles vaccine is that it prevents the painful and disfiguring disease. This study shows us another benefit of the shingles vaccine in reducing the risk of dementia and Alzheimer’s disease.

Citations

• Dos Reis S, Tran P, Mohanty K, Amill-Rosario A, Johnson A, Ryan K, Alsdurf H, Oraichi D, Yun H. Reduced risk of dementia with recombinant zoster vaccine in US adults age 65 or older. Alzheimers Dement. 2026 May;22(5):e71407. doi: 10.1002/alz.71407. PMID: 42050365; PMCID: PMC13124665.

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