Shingles Link to Dementia: New Study Reveals Surprising Connection

Shingles Vaccination Lowers Dementia Risk

Researchers analyzed electronic health records of more than 100 million people in the United States between 2007 and 2023. After adjusting for over 400 different variables – including chronic conditions, demographics, prescriptions, and doctor visits – they found that the risk of being diagnosed with dementia within three years of vaccination was 27 to 33 percent lower.

The study also revealed that those who had multiple shingles episodes experienced a 7 to 9 percent increased risk of dementia three to nine years after their second outbreak, compared to those who had only one episode.

More Shingles Episodes Equal Higher Dementia Risk

Dementia is influenced by a complex interplay of factors, including genetics, environment, and viral infections. As the number of Americans diagnosed with the disease each year continues to rise, effective treatments remain limited and preventative options, beyond lifestyle changes, are scarce. Despite promising research, the biological mechanisms linking varicella-zoster to dementia remain unclear.

Several theories exist. Researchers suggest that the varicella-zoster virus, even when it doesn’t cause noticeable symptoms, continuously reactivates and may directly affect parts of the brain involved in dementia.

How Could Varicella-Zoster Virus Trigger Dementia?

Another theory centers on the body’s natural immune response to infections – inflammation – and whether viral reactivation has toxic effects on the brain. “It’s not necessarily that the virus is directly attacking brain cells, but that the inflammatory response to the presence of the virus is causing problems,” said Anupam Jena, a physician at Massachusetts General Hospital. Or could it be related to the medications used to treat the painful, debilitating symptoms? “We don’t know,” Jena said.

However, the study’s findings suggest that those who received multiple doses of the shingles vaccine were better protected against dementia. This reinforces previous research indicating that two doses of the Shingrix vaccine, rather than one, reduce varicella-zoster virus reactivation. The findings could influence future vaccination recommendations and strategies.

Does Varicella-Zoster Virus Contribute to Neurodegeneration?

Gaining a better understanding of whether the varicella-zoster virus contributes to neurodegeneration is a step toward better dementia treatments, said Patrick Schwab, the study’s lead author and senior director for machine learning and artificial intelligence at GSK, a biopharmaceutical company that manufactures one of the shingles vaccines.

The study found that individuals who received two doses of Shingrix, a newer vaccine containing inactivated parts of the virus manufactured by GSK, had an 18 percent lower risk of dementia five years after vaccination. This was compared to those who received one dose of Zostavax, an older vaccine made from live, weakened zoster viruses. (Zostavax was discontinued in the U.S. in 2020.)

Researchers also found that women over 50 who received Zostavax had a 35 percent lower risk of dementia three years after vaccination. Women between 80 and 89 who received two doses of Shingrix had a 39 percent lower risk three years after vaccination. “The consistency of the findings was really remarkable,” said Schwab, who also leads the biomedical AI group at GSK. “And that’s what ultimately made the study so exciting.”

One “tricky aspect of the study,” Schwab noted, was that it could only measure varicella-zoster cases that were listed as a herpes zoster diagnosis in clinical records. This means it was a “proxy for general reactivation.”

What Does This Mean for Patients?

Shingles vaccines are already recommended for older adults (typically over 50) and people with weakened immune systems. Some doctors said the evidence is now compelling enough that they will discuss dementia prevention as an additional benefit with their patients. Jena, the Joseph P. Newhouse Professor of Health Policy at Harvard Medical School, said he recently addressed the research when teaching a group of medical residents who had never heard of the connection.

Jena had peer-reviewed an earlier study co-authored by Geldsetzer that examined more than 280,000 adults in Wales. It found that people who received the shingles vaccine had a 20 percent lower risk of dementia over a seven-year period.

He said the latest study adds to the robustness of the findings and provides “pretty good quality evidence.” When examining the effectiveness of both vaccines in preventing dementia, researchers found that the brain benefits weren’t permanent, appearing to wane with the vaccines’ diminishing protection.

AM Barrett, chair and professor of neurology at UMass Chan Medical School, said current options for reducing dementia risk are limited and not particularly effective. Barrett, a neurologist who also serves as chief of neurology at the VA Central Western Massachusetts Healthcare System, expressed concern that the topic could become politicized, contributing to growing distrust in medicine and vaccine hesitancy.

“Unfortunately,” she said, “people who aren’t personally affected by dementia might see this as an attempt to talk them into getting an unnecessary vaccine.” However, she added that vaccination is a relatively inexpensive and widely available intervention. “You want to be able to play with your grandkids for five more years and drive well for five more years,” she said. “That’s priceless.”

We are currently testing machine translations. This article was automatically translated from English to German.

This article first appeared on November 9, 2025, at Washingtonpost.com – it is now also available to readers of the IPPEN.MEDIA portals in translation as part of a cooperation.