Pascal Geldsetzer on the Link Between the Shingles Vaccine and Dementia

Pascal Geldsetzer, MD, PhD, Assistant Professor of Medicine in Primary Care and Population Health at Stanford, joins The Future of Medicine to discuss a striking line of research: evidence that shingles vaccination may reduce the risk of dementia.

Geldsetzer and his team study “natural experiments” — real-world situations that can allow researchers to get closer to determining cause and effect without conducting a traditional randomized clinical trial. In the case of shingles vaccination, age-based eligibility rules created unusually comparable groups of people: those born just before a cutoff were not eligible for the vaccine, while those born just after it were.

Using these natural experiments, Geldsetzer’s team has found evidence across several countries that shingles vaccination is associated with a substantial reduction in dementia risk. In one analysis, the researchers estimated that vaccination reduced the risk of dementia over seven years by about 20%. Similar patterns have appeared across different datasets and health systems, as well as in studies examining mild cognitive impairment and outcomes among people already living with dementia.

The conversation explores why a vaccine designed to prevent shingles might affect the brain. Geldsetzer discusses possible roles for the virus that causes chickenpox and shingles, inflammation, blood vessel health, and broader effects of vaccination on the immune system. He also explains an important open question: much of the strongest evidence comes from an older live-attenuated shingles vaccine, so additional research is needed to understand whether newer shingles vaccines have similar effects on dementia.

Thank you for listening!

Call to action: If you enjoy The Future of Medicine, subscribe for more conversations with leading scientists shaping the next era of healthcare. Please rate and review the podcast to help others discover these important discussions. Share with friends and colleagues who are curious about how science becomes medicine.