Your Shingles Jab Might Cut Dementia Risk. Here's Why.

A 68-year-old patient sat in my clinic last week and asked me a question that genuinely caught me off guard. "Doctor, my friend told me the shingles vaccine can prevent dementia. Is that just TikTok nonsense or is it actually true?"

Here is the honest answer. It is not TikTok nonsense.

Across four serious, peer-reviewed papers published between 2024 and 2026, the shingles vaccine has been linked to a meaningful reduction in the risk of dementia. We are not talking about a fringe paper in an obscure journal. We are talking about Nature. Nature Medicine. Nature Communications. Cell. These are four of the most prestigious journals in biomedical science, and they have, more or less independently, arrived at the same message.

And in Singapore, the timing could not be better. As of 1 September 2025, Shingrix is part of the National Adult Immunisation Schedule (NAIS) for adults aged 60 and above. If you or your parents are 60 or older, this is a conversation that matters this week, not "one day."

Let me walk you through why.

The Wales Natural Experiment That Started the Avalanche

In April 2025, a team led by Eyting and colleagues published a paper in Nature that is, to my mind, one of the cleanest real-world studies we have on vaccines and dementia.

Here is what made it special. When the NHS in Wales rolled out the live shingles vaccine (Zostavax), they set a strict eligibility rule by date of birth. If you were born before 2 September 1933, you were never eligible. If you were born on or after that date, you got offered the jab. So two groups of older adults, separated by literally a week or two in age, effectively became a randomised trial by accident. Same genetics, same postcodes, same NHS, same everything. Just a birthday.

That turned 0.01% vaccine uptake just above the cut-off into 47.2% uptake just below it. Almost pure chance, which is the gold standard for saying "this vaccine caused the effect," not just "people who took the vaccine happened to do better."

The result over the next seven years: among people who received the shingles jab, the probability of a new dementia diagnosis was about 20% lower than in the group who missed eligibility by a week. And the vaccine did not reduce any other common cause of death or illness. It specifically moved the dementia needle.

But Singapore Doesn't Use That Vaccine Anymore

Fair point. The Wales study used the older live Zostavax vaccine, which has largely been retired in Singapore and most high-income countries. What we use now is Shingrix, a recombinant (non-live) vaccine that is more effective against shingles itself.

So does the newer vaccine also help the brain?

In July 2024, a team from Oxford published a study in Nature Medicine that looked at more than 200,000 US adults who had received either Zostavax or Shingrix (the US switched between them in October 2017, which gave researchers another natural experiment). Those who got Shingrix had a 17% increase in dementia-free time over six years. In people who eventually did develop dementia, that translated to roughly 164 extra days living without a dementia diagnosis. Better than the old vaccine, on top of a baseline benefit.

Then in 2026, researchers at Kaiser Permanente published in Nature Communications what is arguably the strongest evidence yet. They followed 65,800 adults aged 65 and above who had received two doses of Shingrix, matched with 263,200 unvaccinated peers on age, sex, ethnicity, and a huge range of other health factors. Two doses of Shingrix were associated with a 51% reduction in dementia risk.

Fifty. One. Percent.

The effect was seen in both sexes (hazard ratio 0.45 in women, 0.55 in men), and it held up after careful adjustment for the "healthy vaccinee" bias (the tendency for healthier people to get vaccinated in the first place).

And If You Already Have Dementia?

In December 2025, researchers published in Cell what might be the most surprising finding of all. In people who already carried a dementia diagnosis, receiving the shingles vaccine was associated with lower mortality and slower dementia-related death rates. It is not a cure. But it hints that the benefit is not purely about preventing the disease. Something about the vaccine may also slow its progress.

Why on Earth Would a Skin Vaccine Touch Your Brain?

This is the bit that makes your GP raise an eyebrow. Here is the best current explanation.

If you had chickenpox as a child (and roughly 95% of adults have, even if you do not remember it), the varicella-zoster virus never fully left your body. It retreats into your nerve cells and goes dormant. Decades later, when your immune system weakens with age, stress, or illness, it can reactivate and crawl down a nerve to produce the classic painful shingles rash.

Here is the newer bit. A 2025 study in Nature Medicine based on records from over 100 million US patients showed that even "silent" reactivations (where the immune system controls the virus before you ever notice a rash) appear to drive low-grade inflammation in the nervous system. Chronic neuroinflammation is one of the strongest known drivers of Alzheimer's disease and other dementias.

The Shingrix vaccine does two useful things. It blunts reactivations, reducing that inflammatory load. And the AS01 adjuvant inside it (the bit that revs up your immune response) appears to have broader, trained-immunity effects on the brain that may be independently protective.

We do not yet know exactly which of these mechanisms is doing the heavy lifting. That is an active research area. But the epidemiology keeps pointing in the same direction across countries, vaccine types, and study designs. That kind of consistency is rare in biology.

Why This Matters Especially in Singapore

Let me bring this home.

According to the Well-being of the Singapore Elderly (WiSE) 2023 study, the prevalence of dementia among Singaporeans aged 60 and above is approximately 8.8%. That translated to around 74,000 older Singaporeans with dementia in 2022. By 2030, projections suggest this could reach 152,000 as our population ages. By that same year, 1 in 4 Singapore citizens will be 65 or older. That is not a distant statistic. That is your parents. That is you, sooner than you think.

Shingles itself is not a gentle illness either. Globally, about 1 in 3 people will develop shingles at some point in their lifetime, and by age 85 the risk climbs to roughly 1 in 2. In Singapore, local primary care data show annual incidence rates of 410 to 829 cases per 100,000 in adults aged 50 and above. For the subset who develop post-herpetic neuralgia (nerve pain that can outlast the rash by months or years), it can genuinely be debilitating.

So even before you factor in the dementia benefit, there is a strong standalone case for the vaccine.

What You Should Actually Do

If you are 60 or above (or immunocompromised between 18 and 59), here is my practical take.

1. Book the full two-dose course. One is not enough.

Shingrix is given as two doses, 2 to 6 months apart. The 51% dementia reduction in the Kaiser Permanente study specifically refers to two doses. Plenty of people start the course and never go back for the second. Do not be that person. Put the second dose in your calendar the day you book the first.

2. Check your subsidies.

At CHAS GP clinics and polyclinics under NAIS, eligible Singaporeans can expect to pay around $76 to $300 out of pocket for the complete two-dose course, depending on your CHAS card status, per capita household income, or whether you are a Pioneer Generation or Merdeka Generation senior. Healthier SG enrolees can receive it fully subsidised at their enrolled polyclinic. From mid-2026, MediSave500/700 and Flexi-MediSave can also be used to cover the post-subsidy cost. At a non-NAIS private clinic without subsidy, expect to pay somewhere between $375 and $950 for the two-dose course depending on the clinic. Ask about bundled pricing.

3. Do not wait until you turn 65.

Dementia risk rises steeply from the late 60s, but the immunity you build with Shingrix starts protecting you from day one. Every year you delay is a year of preventable low-grade viral reactivation. If you are 60 now, start now. If your parents are in their 70s and haven't had it, book theirs too.

4. If a parent has early dementia, still discuss it.

The Cell 2025 study specifically suggested benefit in people already diagnosed. It is not a treatment, and it is not a substitute for standard dementia care, cognitive rehab, or the cardiovascular and metabolic basics. But the mortality signal is striking enough that it is worth raising with the treating doctor, especially if the patient has never been vaccinated.

5. Keep doing the boring basics.

A vaccine is an add-on, not a replacement. The Lancet Commission on dementia prevention still tells us the biggest modifiable risk factors are managing blood pressure, blood sugar, and cholesterol, staying physically active, treating hearing loss, addressing depression, avoiding smoking and excess alcohol, staying socially engaged, and getting enough good-quality sleep. These remain the heavyweight champions. The vaccine sits on top of all of that.

What This Is Not Saying

A bit of honesty. Most of these studies are observational, not randomised controlled trials. The Wales natural experiment is the closest thing we have to a true causal design, and it is a pretty strong design, but no study is perfect.

There could still be residual confounding. People who choose to get vaccinated may also happen to sleep more, exercise more, eat better, or show up to their doctor earlier. Researchers have worked hard to adjust for this (matching, stratifying, using natural experiments). Still, the honest read is that we cannot yet say with 100% certainty exactly how much of the benefit is vaccine and how much is "healthy vaccinee."

A randomised controlled trial with 200,000 people followed for 10 years is probably never going to happen, for ethical and practical reasons. So this convergence of evidence is the best signal we are likely to get. It is, by any reasonable standard, a strong one.

The Bottom Line

If you are 60 or older in Singapore, the Shingrix conversation is a this-month conversation, not a someday conversation. Two shots, 2 to 6 months apart, now on NAIS and subsidised. The evidence that it meaningfully lowers dementia risk sits on four top-tier peer-reviewed papers published in two years, and the effect sizes range from 17% to 51% depending on the study design.

We do not often get interventions in medicine where the evidence quietly converges from four different angles in such a short window. When it does, you do not wait.

Book it. Get both doses. Tell your parents. Keep lifting, sleeping, walking, connecting, and eating your greens. It all compounds.

Your future brain will thank you.

References

1. Eyting M, Xie M, Michalik F, et al. A natural experiment on the effect of herpes zoster vaccination on dementia. Nature. 2025;641:438-446. 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. Nature Medicine. 2024;30(10):2777-2781. DOI: 10.1038/s41591-024-03201-5
3. Rayens E, Sy LS, Qian L, et al. Recombinant zoster vaccine is associated with a reduced risk of dementia. Nature Communications. 2026;17:2056. DOI: 10.1038/s41467-026-69289-0
4. Pomirchy M, Bommer C, Pradella F, et al. The effect of shingles vaccination at different stages of the dementia disease course. Cell. 2025;188(26):7331-7345.e10. DOI: 10.1016/j.cell.2025.10.040
5. Taquet M, Todd JA, Harrison PJ. Varicella-zoster virus reactivation and the risk of dementia. Nature Medicine. 2025. DOI: 10.1038/s41591-025-03972-5
6. Subramaniam M, Abdin E, Shafie S, et al. Prevalence of dementia in Singapore: Changes across a decade. Alzheimer's & Dementia. 2025. DOI: 10.1002/alz.14485
7. Ministry of Health Singapore. New Vaccines Against Shingles and Pneumococcal Disease Added to National Adult Immunisation Schedule. MOH Newsroom; 2025. URL: moh.gov.sg
8. Ministry of Health Singapore. Subsidies and MediSave Coverage for Shingles Vaccine. MOH Newsroom; 2025. URL: moh.gov.sg
9. 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
10. Chen MI, Lee VJM, Koh CHK, et al. Public health impact of herpes zoster vaccination on older adults in Singapore: a modeling study. Human Vaccines & Immunotherapeutics. 2024. DOI: 10.1080/21645515.2024.2348839