Brown University study finds Shingrix linked to 24% lower dementia risk in older adults

# What the study found A team at Brown University analyzed electronic health records and Medicare claims for 509,926 U.S. adults aged 66 and older who were admitted to skilled nursing facilities. People who received at least one dose of the recombinant zoster vaccine (commercially Shingrix) experienced a 24% relative reduction in the risk of being diagnosed with dementia over a four-year follow-up period compared with those who did not receive the vaccine.

# Why researchers caution against interpreting this as proof The study authors and independent clinicians emphasize that the result demonstrates an association, not proof that Shingrix prevents dementia. Observational analyses of health records can show consistent links but cannot by themselves establish causation because unmeasured factors could influence both the likelihood of vaccination and dementia risk.

# Possible explanations researchers consider Researchers have proposed several plausible pathways that could connect shingles vaccination and lower dementia diagnoses:

• Preventing shingles and its complications. Herpes zoster infection can cause complications that may affect brain health.
• Reducing vascular events. The varicella-zoster virus has been linked to vascular problems such as stroke, which can contribute to vascular dementia.
• Broader cardiovascular benefits. Some recent literature reports cardiovascular risk reductions after shingles vaccination, which could indirectly influence dementia risk.

# How this study fits with prior research Neurologists not involved in the Brown analysis noted the new paper aligns with earlier studies that showed similar associations between shingles vaccination and slower cognitive decline or lower dementia incidence. The reporting cites this study as the latest in a series of observational findings on the topic.

# What the study did and did not do

# What readers should take away The data show a consistent and measurable association between receiving Shingrix and lower dementia diagnoses in this study population. That association contributes to an accumulating body of observational evidence but does not by itself demonstrate causation. Clinicians quoted in the coverage describe the finding as "remarkable" while still urging interpretation within the limits of observational research.

# Practical considerations People deciding about shingles vaccination should weigh established benefits of Shingrix—namely, strong protection against shingles and its direct complications—alongside ongoing research into possible additional effects on vascular and cognitive outcomes. Conversations with a primary care clinician can help individuals consider vaccine timing and eligibility in the context of their overall health and risks.