Shingles is caused by the varicella-zoster virus, the same virus responsible for chickenpox. The virus remains dormant in nerve cells and can reactivate later in life, particularly as the immune system weakens with age.

While the vaccine is designed to prevent this painful condition, researchers theorized it might also protect brain health. Some viral infections have been linked to a higher risk of dementia, suggesting that preventing reactivation of the varicella-zoster virus could play a role in preserving cognitive function.

Findings Consistent Across Multiple Countries

Intrigued by their findings, Geldsetzer’s team replicated the study using health records from England, Australia, New Zealand, and Canada—and observed the same strong protective effect against dementia in every dataset.

Interestingly, the benefit was more pronounced in women than in men, possibly due to women’s stronger immune response to vaccines or the fact that shingles is more common in women.

Does the Newer Shingles Vaccine Offer the Same Protection?

One key question remains unanswered: Would the newer shingles vaccine, Shingrix, provide the same dementia protection?

The original vaccine, Zostavax, used a live but weakened form of the varicella-zoster virus to trigger immunity. However, it has since been replaced by Shingrix, a more effective genetically engineered version that contains only select viral proteins. While Shingrix provides 97% protection against shingles (compared to 51% for Zostavax), its effect on dementia risk is still unknown.

Geldsetzer hopes these findings will encourage further research into Shingrix’s potential cognitive benefits. "Investing resources into investigating these pathways could lead to breakthroughs in treatment and prevention," he concluded.

If confirmed, these results could position the shingles vaccine as a dual-purpose tool—not just for preventing a painful viral infection, but also for protecting against dementia in aging populations.