Older adults who received the recombinant zoster vaccine (Shingrix) after being admitted to a skilled nursing facility showed a 24% lower risk of receiving a new dementia diagnosis over a four-year period, according to a study published in the Annals of Internal Medicine. Researchers analyzed Medicare data from more than 500,000 patients and found that vaccination, which is used to prevent shingles, may offer neuroprotective benefits.
Study Methodology and Findings
Researchers from Brown University, the University of Delaware, and the Providence Veterans Affairs Medical Center conducted a target trial emulation to assess the link between the shingles vaccine and dementia. The study followed 509,926 Medicare beneficiaries aged 66 and older who were admitted to skilled nursing facilities between 2017 and 2022.
Participants were required to have no prior dementia diagnosis and be eligible for the Shingrix vaccine. Among the study population, 8,843 individuals received at least one dose of the vaccine. After four years of follow-up, the data indicated that 18.8% of vaccinated adults were diagnosed with dementia, compared to 24.6% of those who remained unvaccinated.
"This translates to about one in 17 dementia cases potentially being prevented," said lead study author Kaley Hayes, an assistant professor at Brown University’s School of Public Health.
Contextualizing Neuroprotective Benefits
The results add to an emerging body of research suggesting that certain vaccines may protect against cognitive decline. While earlier studies focused on a prior shingles vaccine, this analysis specifically examined the recombinant vaccine (RZV), which has been the only shingles vaccine available in the U.S. since 2017.
"It fits into this large puzzle that’s just starting to come together that the vaccines are effective at preventing shingles and also appear to have neuroprotective benefits as well," said Hayes.
Limitations and Future Research
Despite the findings, the study authors emphasized that the results do not definitively prove that the vaccine causes a reduction in dementia risk. Vaccinated individuals in the study were, on average, slightly younger and exhibited better baseline health than their unvaccinated counterparts. Although the research team adjusted for these disparities, the authors noted that unmeasured confounding factors could still influence the results.
Clinical trials will be necessary to establish a direct causal relationship between the vaccine and dementia prevention. The researchers acknowledged that the study was funded by GlaxoSmithKline, the manufacturer of Shingrix, but stated that the company had no involvement in the study design, data analysis, or the decision to publish the findings.
Frequently Asked Questions
What is the current shingles vaccine recommendation for older adults?
The sources do not provide information on current CDC recommendations.
Does this study prove the vaccine prevents dementia?
No. The study identifies an association between vaccination and a lower risk of dementia diagnosis but does not prove the vaccine is the direct cause of this reduced risk. Further randomized clinical trials are required to confirm these findings.
Who was included in the study?
The study included Medicare beneficiaries aged 66 and older admitted to skilled nursing facilities for short- or long-term care between 2017 and 2022. All participants had no prior history of dementia at the start of the observation period.
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