Shingles Vaccine May Help Protect Against Dementia, Study Suggests

 

  A new study has found a surprising benefit of the shingles vaccine: it may reduce the risk of developing dementia. The research, published in JAMA on April 23, supports the idea that viral infections — especially those caused by herpesviruses — might play a role in the development of Alzheimer’s disease and other forms of dementia.

The Study: What Researchers Discovered

    Researchers analyzed electronic health records from across Australia to explore the effects of the country’s free shingles vaccination program, which began in 2016. The program offered the vaccine to adults aged 70 to 79, but those who turned 80 before November 1, 2016, were not eligible.

    This created a unique situation similar to a clinical trial, with one group eligible for the vaccine and another group not — despite being born just a few days apart. Because the groups were so similar in age and background, researchers were able to isolate the effect of the vaccine more confidently than in previous studies.

Key Findings

• Over a 7.4-year follow-up period, the dementia diagnosis rate was 1.8 percentage points lower in those eligible for the shingles vaccine.
• 3.7% of vaccinated individuals were diagnosed with dementia, compared to 5.5% in the non-vaccinated group.
• The difference was not seen for other conditions like heart disease, diabetes, or hypertension, suggesting a specific protective effect against dementia.

Why This Matters

    These findings support the “viral hypothesis” of Alzheimer’s disease, which proposes that viruses — particularly herpesviruses — may contribute to brain degeneration. The varicella-zoster virus, which causes chickenpox and shingles, can lie dormant in the nervous system for years and may reactivate later in life. This reactivation could potentially damage brain tissue and trigger or accelerate dementia.

    The shingles vaccine prevents this virus from reactivating, which could help reduce that risk.

    Dr. Sten Vermund, Dean of the University of South Florida College of Public Health, who was not involved in the study, said:

    “It is very hard to see how anything other than the vaccine could explain the strong protective effect.”

Why This Study Stands Out

    Past studies have shown that people who get vaccinated tend to have better health outcomes in general — they exercise more, eat healthier, and visit doctors regularly. This makes it difficult to say whether the vaccine itself or healthy habits were behind the reduced dementia risk.

    This new study eliminates much of that bias by comparing two nearly identical age groups — the only difference was whether they were just young enough to qualify for the free vaccine.

    Dr. Pascal Geldsetzer, senior author of the study and assistant professor at Stanford University, explained:

    “All that’s different about these two groups is if they were born a few days earlier or a few days later.”

    This design makes the study feel like a pseudo-clinical trial, offering stronger evidence than traditional observational research.

How Does the Vaccine Protect the Brain?

    Although the exact mechanism is still unclear, there are two main theories:

1. Direct prevention of viral reactivation:
   The shingles vaccine stops the varicella-zoster virus from waking up and possibly harming brain tissue through inflammation or the buildup of harmful proteins.
2. Immune system tuning:
   The vaccine may help modulate the immune system in a way that indirectly slows down or reduces brain degeneration linked to dementia.

More research is needed to determine which — or both — of these theories is correct.

Are There Any Limitations?

    Yes, like any study, this one has its limits.

• It was not a randomized controlled trial (RCT) — the gold standard in medical research.
• It did not examine genetic risk factors, such as the APOE4 gene variant, which is strongly linked to Alzheimer’s.
• It’s unclear whether the vaccine works better in certain groups of people.

Still, experts say the evidence is compelling, especially since a similar study conducted in Wales also found a 20% lower dementia risk among people who had received the shingles vaccine.

    Dr. Geldsetzer and his team now plan to launch a formal clinical trial to test the shingles vaccine’s protective effects against dementia. They’re seeking private and philanthropic funding to make this happen.

    If confirmed, this research could have enormous implications. The shingles vaccine is already widely available, low-cost, and safe — and it could become a powerful tool in preventing or delaying dementia, one of the most challenging health conditions facing aging populations.

  The shingles vaccine might do more than protect you from a painful rash — it could help guard your brain, too. While more research is needed, this study provides strong evidence that preventing viral reactivation may be a key part of reducing dementia risk.

    If you're eligible for the shingles vaccine, it may be worth discussing with your healthcare provider — not just for your skin, but for your brain.

Disclaimer: The health tips shared on this blog are for informational purposes only and are not a substitute for professional medical advice. Always consult a qualified healthcare provider before making changes to your health routine. Content is based on publicly available sources and edited for clarity.