Quick version
Over a period of about 10 years, several large studies have shown that people who have been vaccinated against shingles are less likely to develop dementia compared to those who are unvaccinated. The numbers show that up to 15–50 percent of those who were vaccinated have about a 20 percent lower risk of dementia during the first seven years after receiving an older shingles vaccine. Research on the modern vaccine shows a similar or slightly greater risk reduction.
These findings still represent associations in observational studies rather than clear proof, but the results are consistent enough that researchers view the shingles vaccine as a potential piece of the puzzle in long-term dementia prevention.
What is the connection between shingles and dementia?
The herpes zoster virus remains latent after chickenpox
Shingles is caused by the varicella zoster virus, the same virus that causes chickenpox. After a person has had chickenpox, the virus remains dormant in nerve cells near the spinal cord and the brain. It can therefore reactivate and cause shingles later in life, often when the immune system becomes weakened.
Believed to cause inflammation in the nervous system
Long-term, low-grade inflammation in the brain is commonly seen in patients with dementia. Many viral infections, including herpes viruses, are believed to worsen inflammation. A shingles virus that reactivates several times can cause more severe inflammation in the nervous system.
Because the shingles virus can lead to inflammation in the nervous system, it is believed to contribute to an increased long-term risk of dementia. The shingles vaccine reduces the risk of both shingles and silent reactivations of the virus, and may therefore indirectly reduce inflammation in the brain.
What does the research show about shingles vaccination and dementia risk?
Several large studies have been conducted
In 2013, Wales introduced a vaccination program where a strict age limit determined who was eligible for the free vaccine. This allowed researchers to compare similar groups. Just over 280,000 people were followed for about seven years, and the results showed that those offered the shingles vaccine had about a 20% lower risk of developing dementia. A similar study conducted in Australia also showed around a 20% lower relative risk of dementia after vaccination.
More recent studies on the modern recombinant shingles vaccine (such as Shingrix) also show a reduced risk of dementia. In a larger study, vaccinated individuals had, on average, a longer period without a dementia diagnosis compared to comparable unvaccinated individuals. Other analyses show that the vaccine also appears to reduce the risk of cardiovascular disease in people over 50.
How large is the risk reduction?
The results regarding shingles vaccination are consistent but vary slightly between studies. Overall, the risk of dementia is estimated to be about 15–20% lower for individuals who have been vaccinated compared to those who have not.
- Approximately 15–30% lower risk of receiving a dementia diagnosis during the first 5–7 years after vaccination.
- The effect is seen in both men and women.
- The protection appears to be strongest in the first years and may decrease over time.
Can the shingles vaccine prevent dementia?
Strong association – but no definitive proof
There are clear associations, but large randomized studies are still lacking. Therefore, researchers say that the shingles vaccine “may” help prevent dementia, but that it is not yet fully proven.
Why the vaccine may protect the brain
- Lower risk of viral reactivation: fewer reactivations of herpes zoster in the nervous system
- Trained immune system: some vaccines stimulate the immune system and may suppress low-grade inflammation
- Fewer complications: even if you do get sick, the vaccine reduces the risk of severe shingles, pain, and hospitalisation, which may benefit brain health.
Future research
Several questions remain unanswered — for example, whether the protection applies to all forms of dementia, whether booster doses are needed, whether genetic factors influence the effect, and whether the vaccine can slow already developing dementia. To determine definitively whether the vaccine actually reduces dementia risk, randomized studies, longer follow-up, and direct comparisons between vaccine types are needed.
The doctor answers and explains
Erik Lind is a specialist in geriatrics with many years of experience working with older patients, particularly in memory assessments, brain health, and preventive care. Here he comments on the research and gives his expert assessment of what the findings mean in practice for older adults and other risk groups.
How strong do you consider the evidence to be that the shingles vaccine reduces the risk of dementia?
– Much suggests that the shingles vaccine can reduce the risk of developing dementia by around 20–30% in older populations, but this is mainly based on observational data. It is not yet definitively proven that the vaccine causes this reduced risk, and more controlled research is ongoing. The mechanisms underlying this connection may revolutionize the way we prevent dementia.
Which age groups do you believe have the most to gain from vaccination, considering a possible effect on dementia risk?
– The relative risk reduction is greater the older the patient is, and women generally get better protection from vaccination.
What would you like to see in future studies in order to recommend vaccination specifically for dementia prevention?
– The studies have been conducted on older populations (mainly 70+). Since dementia diseases typically appear at older ages, a study where younger individuals are vaccinated would take a very long time to complete, but it would give a clearer picture of the long-term effect. A study examining how the vaccine affects — and potentially reduces — dementia that appears at younger ages would also be interesting.
How should an older person think about vaccination when also considering brain health?
– Get vaccinated!
Which other measures are as important or more important than vaccination for preventing dementia?
– It is difficult to generalize, but in general, lifestyle factors are the single most important modifiable factors that individuals can influence to reduce their risk. Without particular order, I recommend avoiding excessive/chronic stress, sleeping regularly and enough, maintaining an active social life and staying mentally engaged. It is also important to exercise, avoid overweight and processed foods, drink alcohol in moderation, and avoid all forms of tobacco.
Having well-managed chronic diseases — such as hypertension, hyperlipidemia, diabetes, inflammatory diseases, and other chronic conditions — is also essential for reducing long-term dementia risk. Even though hereditary factors exist, one can reduce the risk of dementia and often delay onset by managing these risk factors.
Having a regular doctor and routinely following up on one’s health is also an important part of dementia prevention.
Recommendations for shingles vaccination in Sweden
The Public Health Agency of Sweden recommends that adults at increased risk of shingles get vaccinated, often from age 65. Two doses are given a few months apart. The vaccine is not part of a national vaccination program, meaning that price and availability may vary between regions.