Common vaccine linked to 24% lower dementia risk in older adults

A recent study led by researchers at Brown University appears to strengthen the link between shingles vaccination and a reduced risk of dementia diagnoses in older adults.

The study, published in The Annals of Internal Medicine, evaluated electronic health records and Medicare claims for more than 509,926 U.S. adults 66 and older who were admitted to skilled nursing facilities.

Individuals who received at least one dose of the recombinant shingles vaccine, commercially known as Shingrix, experienced a 24% relative reduction in dementia risk over a four-year period compared to people who did not receive the shot, the researchers found.

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However, the findings show an association and do not prove that the vaccine directly prevents dementia, the researchers noted.

Dr. Ajeet Sodhi, a clinical neurologist and neuro-interventionalist in Orlando, Florida, noted that while the finding is "remarkable," it builds upon a growing foundation of scientific literature rather than standing alone.

"This is maybe the third or fourth study, and they all came to the same conclusion," Sodhi, who was not involved in the study, told Fox News Digital. "It seems that by giving patients the shingles vaccine called Shingrix, in the next couple of years, we see a clinically significant decline in the development of dementia."

Researchers have proposed several possible explanations for the association, including the vaccine's role in preventing shingles and its potential complications. The virus has also been linked to vascular events such as stroke, which can contribute to vascular dementia.

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Sodhi noted that recent medical literature continues to support larger cardiovascular benefits as well.

"In addition to the study that we're talking about today, there was a study published just this week that showed the shingles vaccine results in a clinically significant reduction in the incidence of both cardiovascular disease and cerebrovascular disease," he told Fox News Digital.

"So that's heart attacks and strokes."

The neurologist emphasized that while the data shows a strong correlation, the vaccine is not currently classified as a direct therapeutic treatment for cognitive decline.

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"It's not at this time considered a treatment," he noted. "This association is ... very, very suggestive, but we can't say one-to-one it proves that this treats dementia. And this finding, honestly, is kind of like icing on the cake."

Shingles is caused by the varicella-zoster virus, the same virus responsible for chickenpox, according to Mayo Clinic.

After a person recovers from chickenpox, the virus lies dormant in nerve tissue near the brain and spinal cord, where it can reactivate decades later as a painful rash with fluid-filled blisters.

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The primary function of the vaccine remains the prevention of the severe nerve pain and rash caused by shingles reactivation.

Shingles can lead to severe complications, including post-herpetic neuralgia, a debilitating condition causing long-term nerve pain that persists after the rash clears, according to Cleveland Clinic.

The Centers for Disease Control and Prevention recommends two doses of Shingrix for adults 50 and older, as well as adults 19 and older who are or will be immunocompromised. The vaccine is FDA-approved to prevent shingles and related complications — not to prevent or treat dementia.

The study received funding from GSK, the maker of Shingrix; the authors stated that the company had no role in the study’s design, analysis or publication.

For individuals concerned about memory loss or family medical history, experts recommend consulting a doctor early.

"The common theme in all of this is the sooner you seek evaluation, the better it is for the treatment," Sodhi advised. "The treatment is more likely to work the earlier you are in the onset of the disease."