Shingles Vaccine and Brain Health: What the Research Shows
For this group of people in Wales, shingles vaccine eligibility was determined by birth date as of September 2013. People who were age 80, born before September 2, 1933, were not eligible for vaccination, while those born on or after that date were, providing researchers with the opportunity to do a large-scale study comparing vaccinated and unvaccinated people. The study found that at follow-up seven years later, those who received the vaccine had a 20 percent lower risk of developing dementia. The researchers said the study was as close to a randomized, controlled trial — considered the gold standard in research, in which a treatment group is compared with a control group who received no treatment — as you could get without conducting one.
And the research on the link has grown, according to Jason Tetro, a microbiologist in Edmonton, Canada, and the author of The Germ Files and The Germ Code. “Since then other studies have either confirmed or added more valuable information to show that getting the shingles vaccine does indeed help to reduce the risk or severity of dementia,” he says.
Conversely, research has found that people who experienced shingles had about a 20 percent higher risk of later reporting cognitive decline. In a separate observational study following more than 149,000 middle-aged and older adults for over a decade, researchers noted that those who had the virus reactivate were more likely to report early cognitive impairment symptoms, such as memory lapses and confusion that can indicate dementia later on.
While these findings are promising, evidence is still evolving and has a long way to go before the vaccine is recommended to prevent or treat dementia, says William Schaffner, MD, a professor of infectious diseases at Vanderbilt University in Nashville, Tennessee, and a spokesperson for the Infectious Diseases Society of America.
He calls the research “early, but accumulating. It’s provocative, it’s exciting, and it’s absolutely fascinating” from the point of view of how a disease develops.
Researchers are still working to understand the link, though. “The question right now is why – that’s what we’re not totally sure of,” says Ankush Bansal, MD, a lifestyle medicine physician and hospitalist in Westlake, Florida.
One leading theory centers on inflammation, Dr. Bansal says. When the varicella-zoster virus reactivates later in life as shingles, it triggers a widespread inflammatory response in the body. That inflammation goes beyond skin deep, affecting the nervous system and, potentially, the brain.
“Inflammation from shingles may contribute to vascular damage and neurological effects, and reducing that inflammatory burden may lower long-term risk,” he says.
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