Shingles Vaccine Linked to 24% Lower Dementia Risk in Older Adults

Study Findings on Dementia Risk

Older adults who received the Shingrix shingles vaccine were 24% less likely to be diagnosed with dementia over a four-year period. The findings are based on an analysis of health records and Medicare data from more than 500,000 adults aged 66 and older who were admitted to skilled nursing facilities for either short-term or long-term care.

Researchers estimate that the difference in risk could result in approximately one dementia case being prevented for every 17 people vaccinated. The study specifically compared individuals who received at least one dose of the recombinant shingles vaccine, known as RZV or Shingrix, against those who remained unvaccinated.

Research Methodology and Publication

The research was led by Daniel Harris, an assistant professor of epidemiology at the University of Delaware College of Health Sciences. The study's results were published in the *Annals of Internal Medicine*, a peer-reviewed medical journal.

According to source materials, the two-year investigator-initiated study received funding from GlaxoSmithKline, the manufacturer of the Shingrix vaccine. The research involved collaborators from Brown University.

Potential Biological Mechanisms

While the study establishes a link, researchers are examining why the vaccine may protect the aging brain. An editorial in *Clinical Infectious Diseases* has proposed three possible explanations for the observed reduction in dementia risk.

One theory suggests that the vaccine may reduce the cumulative burden of virus reactivation. This includes episodes of reactivation that may be so mild they go unnoticed by the patient but can still inflame and injure brain tissue over time.

Clinical Context

Shingrix is currently the only available and recommended shingles vaccine in the United States. The study focused on adults in skilled nursing facilities, a population that is known to be at a high risk for dementia.

Previous research has indicated that an older version of the shingles vaccine, Zostavax, may also provide protection against dementia. However, this recent study focuses on the updated recombinant version currently in use.