Vaccine May Reduce Risk of Dementia and Shingles
As we age, the likelihood of developing both dementia and shingles tends to increase. But what if there was a single vaccine that could shield us from both conditions?
There’s already some solid evidence pointing to an older shingles vaccine—known as Zostavax—being effective against dementia. Now, a newer vaccine, Shingrix, has not been studied as thoroughly, which is something a research team from Brown University aimed to change.
In their recent investigation, researchers examined data from 509,926 individuals who were admitted to nursing facilities between January 2017 and December 2022. This demographic served as a practical health benchmark since these individuals are already at heightened risk for both dementia and shingles.
Over a follow-up period of four years, the findings revealed that 18.8 percent of those who received a Shingrix vaccination within a year of their admission developed dementia. In contrast, the figure rose to 24.6 percent among those who did not get vaccinated. That’s a notable 24 percent reduction in risk.
“This study focuses on the latest vaccine within an older, at-risk adult population that has not been current with their shingles vaccinations and is clearly entering a skilled nursing facility,” comments Kaley Hayes, a pharmacoepidemiologist at Brown University.
She further notes, “It contributes to a growing understanding that vaccines are not just effective for preventing shingles but may also offer protective benefits for brain health.”
Shingrix has since taken the place of Zostavax in many regions because it’s more effective and provides longer-lasting results. Importantly, this research isn’t the first to draw a link between this vaccine and lower dementia risk.
The strengths of this study lie in its substantial sample size, real-world context, and its focus on those particularly vulnerable due to age and nursing care needs. However, during the research period, only 8,843 out of the nearly 510,000 participants chose to receive the Shingrix vaccine—an uptake deemed relatively low. Researchers hope the demonstrated 24 percent reduction in dementia risk could persuade more individuals to seek this protection.
“That statistic equates to roughly one in 17 dementia cases that might be avoidable,” Hayes mentions.
Of course, there are limitations to consider. Since this is an observational study, establishing a direct cause-and-effect relationship is tricky. Additionally, there’s a potential “vaccine bias,” meaning those in better health—who may have a lower risk for dementia—might be more inclined to get vaccinated.
It’s also unclear why this association exists, but that’s a question for future research.
“We can’t definitively explain why the risk of dementia is reduced with shingles vaccination, although we have several hypotheses,” Hayes shares. “One clear factor is likely the reduction of shingles infections, which can cause neuroinflammation and elevate stroke risk.” She mentions emerging theories that vaccines fostering robust immune responses could also play a role.
Notably, the study was funded by GlaxoSmithKline, the company behind Shingrix. Researchers maintain that GlaxoSmithKline had no influence over study design, data analysis, or publication choices.
Given the alignment with previous studies, coupled with longstanding connections between shingles vaccines and dementia risk, there’s a compelling case that Shingrix continues the positive impact previously attributed to Zostavax.
With the CDC advocating for shingles vaccinations for adults over 50 in the U.S., researchers suggest that admission to nursing facilities could serve as an opportune moment to inquire about vaccination.
“Our cognitive health is intricately linked to our overall physical well-being,” Hayes concludes. “It’s remarkable that a vaccine designed to combat a physical condition also seems to support brain health.”
The research findings were published in the Annals of Internal Medicine.
