Study Finds Routine Vaccinations Associated with Lower Dementia Risk

Stanford researchers have discovered new evidence suggesting that the shingles vaccine may slow the progression of dementia, building on previous findings that linked vaccination to a reduced risk of developing the condition.

In a groundbreaking study, researchers found that older adults who received the shingles vaccine Zostavax were not only 20% less likely to develop dementia over a seven-year period, but those already diagnosed with dementia showed significantly improved outcomes.

“For the first time, we now have evidence that likely shows a cause-and-effect relationship between shingles vaccination and dementia prevention and treatment,” said Dr. Pascal Geldsetzer, assistant professor of medicine and senior author of the study, in comments to Fox News Digital.

The research team leveraged a unique opportunity in Wales, where eligibility for the shingles vaccine was strictly determined by birth date for several years. This created a natural experiment where people born just before the cutoff received the vaccine, while those born just after did not. The resulting groups were nearly identical in age, health profiles, and backgrounds, differing only in vaccination status.

This methodological approach helped researchers avoid some of the biases common in observational studies, allowing for more reliable conclusions about the vaccine’s effects on cognitive health.

After initial analysis released in April, the team conducted deeper investigation into patient records and found the benefits extended across the entire spectrum of cognitive decline—from early signs to advanced stages of dementia.

Over a nine-year follow-up period, vaccinated individuals were less likely to be diagnosed with mild cognitive impairment. More strikingly, among those who already had dementia at the start of the vaccination program, the difference in outcomes was substantial. Nearly half of unvaccinated Welsh seniors with dementia died from the condition during the follow-up period, compared to only 30% of those who received the vaccine.

The findings suggest that the shingles vaccine could be beneficial not just for preventing dementia but also for slowing its progression in those already diagnosed.

Dr. Geldsetzer explained the biological mechanism potentially at work: “There is a growing body of research showing that viruses that preferentially target your nervous system and hibernate in your nervous system for much of your life may be implicated in the development of dementia.”

The chickenpox virus, which causes shingles when it reactivates in older adults, remains in the body for life. When it flares up, it can trigger inflammation in or around the brain, according to the Mayo Clinic. By preventing these viral reactivations, the shingles vaccine may reduce inflammation, which has been consistently linked to increased dementia risk.

This research adds to the growing evidence of connections between infectious diseases and neurodegenerative conditions. Preventing or controlling chronic infections may offer a new avenue for addressing dementia, a condition that affects millions worldwide and has limited treatment options.

Despite the promising results, the research team acknowledged an important limitation of their study. People who choose to get vaccinated often have different health behaviors than those who don’t, and these differences could influence outcomes.

“We have very little, if any, information on these behaviors in electronic health records or medical claims data,” Geldsetzer noted. Information about patients’ dietary habits, physical activity levels, and other lifestyle factors that might impact dementia risk was not available in the data.

The researchers emphasized that while their findings are promising, randomized clinical trials would be needed to definitively confirm whether the shingles vaccine can genuinely slow dementia progression.

“If the shingles vaccine really prevents or delays dementia—and, with this new study, also appears to have benefits for those who already have dementia—then this would be a hugely important finding for clinical medicine, population health and research into the causes of dementia,” Geldsetzer concluded.

With dementia affecting approximately 55 million people worldwide and numbers expected to rise with aging populations, any intervention that could prevent or slow the condition would represent a significant public health breakthrough.