Ilaria Rosella Pagliaro Emerging research shows that common vaccines, including shingles, flu, and RSV shots, may lower dementia risk through mechanisms like reduced infections, immune activation, and stroke prevention.
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In recent years, a growing number of studies have highlighted a striking possibility: vaccines, beyond shielding us from viral infections, may also offer a protective effect against dementia—one of the most devastating neurodegenerative diseases, still without a cure. Among them, the shingles (herpes zoster) vaccine stands out as the most promising, associated with a 20% lower risk of developing dementia.
This vaccine was first rolled out in 2006 to prevent the painful skin rash caused by the varicella-zoster virus. But it soon caught the attention of scientists for a different reason. A 2025 study published in Nature followed nearly 300,000 older adults in Wales, comparing people born just weeks apart who had different access to the vaccine depending on their birthdate. After seven years, those who had been vaccinated showed a 3.5% lower absolute risk of dementia—equivalent to a 20% relative reduction.
The latest and more potent version of the vaccine, known as Shingrix, is now recommended by the Centers for Disease Control and Prevention (CDC) for everyone over 50, and for younger adults with weakened immune systems. Yet as of 2022, only about one-third of eligible Americans had received at least one dose.
Other vaccines, same unexpected benefits
The shingles vaccine isn’t the only one showing this kind of connection. Evidence is mounting that seasonal flu, RSV (respiratory syncytial virus), and Tdap (tetanus, diphtheria, pertussis) vaccines might also play a role in protecting the brain.
A large U.S. study of more than 200,000 older adults confirmed that both Zostavax (the older live vaccine) and Shingrix (the newer recombinant vaccine) were linked to lower dementia risk, with Shingrix offering a clear edge. On average, it gave people 164 extra dementia-free days compared to Zostavax.
In 2022, another investigation published in the Journal of the American Geriatrics Society found that individuals who received both the shingles and Tdap vaccines had half the risk of developing dementia compared to those who had not been vaccinated at all.
The influenza vaccine shows similar advantages. A study involving 1.8 million Americans aged over 65 found a 40% reduction in Alzheimer’s risk among those vaccinated. Another 2024 analysis of more than 70,000 people recorded a 17% drop in overall dementia risk.
RSV vaccines are newer on the scene, but they’re already showing intriguing data. Arexvy, recommended for adults over 60, was associated with a 29% decrease in dementia diagnoses in the 18 months following vaccination. Researchers at Oxford University highlighted that this benefit appears despite RSV typically causing only mild symptoms in older adults.
Why might vaccines work against dementia?
While the correlation between vaccines and dementia risk reduction is compelling, scientists are cautious. Most of these studies are observational, meaning they can’t prove direct cause and effect. Still, several plausible biological explanations are emerging.
One involves preventing severe infections. Illnesses like influenza, shingles, and RSV can accelerate brain aging. A 2024 Nature Aging paper showed how such infections trigger inflammatory cascades that promote brain atrophy, increasing dementia risk.
Another focuses on vaccine adjuvants. Some vaccines, including Shingrix and Arexvy, contain an adjuvant called AS01, which boosts the immune response. Laboratory studies suggest this substance may activate immune cells that protect neural tissue, though human evidence remains limited.
A third hypothesis involves stroke prevention. The herpes zoster virus has been linked to a higher likelihood of stroke, a well-established dementia risk factor. By preventing shingles, vaccines may indirectly lower the risk of cerebrovascular events too.
Interestingly, several analyses have observed that the protective effect seems stronger in women than in men, though the reasons for this gender difference are still unclear.
A revolutionary idea: preventing dementia through vaccines
The notion that a simple vaccination could help safeguard the brain from dementia is nothing short of revolutionary. In a world where side effects often mean trouble, this could be a rare example of a beneficial “side effect” with population-level impact.
As Dr. Robert H. Shmerling wrote for Harvard Health Publishing, “Getting vaccinated today protects you from painful diseases like shingles, and potentially, from much more.”
Of course, vaccines aren’t a magic shield. They work best when part of a healthy lifestyle. The 2024 Lancet Commission estimated that up to 45% of dementia cases could be prevented or delayed through lifestyle changes—regular physical activity, blood pressure control, reduced alcohol intake, and treating hearing loss all play crucial roles.
Still, the idea that routine vaccines could become a tool in dementia prevention opens a fascinating new frontier in public health. It’s a story that’s only beginning to unfold.
Source: Nature
