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

A large observational study published in the Annals of Internal Medicine has found that older adults who received the Shingrix shingles vaccine were 24 percent less likely to receive a dementia diagnosis over four years than those who went unvaccinated. Researchers analyzed electronic health records and Medicare claims for more than 509,000 U.S. adults aged 66 and older.

Dementia was diagnosed in 18.8 percent of vaccinated participants during the study period, compared with 24.6 percent of those who did not receive the vaccine. Based on that gap, the researchers estimate that roughly one dementia case could be prevented for every 17 people who receive the vaccine, a substantial potential effect if the relationship holds up under further scrutiny.

The study's authors were careful to note that their design, which compared outcomes for people who chose to get vaccinated against those who did not, can only establish an association rather than prove that Shingrix directly prevents dementia. Differences in overall health behavior between the two groups could partly explain the gap. Shingrix, introduced in 2017, remains the only shingles vaccine currently available, and researchers say the findings support further randomized studies to test whether the protective effect is real and what might explain it.