A large-scale study analyzing data from over half a million individuals suggests that the shingles vaccine may substantially decrease the risk of developing dementia. The research, published in the Annals of Internal Medicine, found that individuals who received the recombinant zoster vaccine, commonly known as the shingles jab, were 24% less likely to be diagnosed with dementia compared to those who did not.
Dementia is an umbrella term for a group of conditions, including Alzheimer's disease, that affect memory, thinking skills, and behavior. It is the leading cause of death in the UK, claiming over 77,000 lives annually. While there is currently no cure for dementia, researchers are exploring potential preventative measures.
The study's participants had an average age of 79, with nearly two-thirds being women, demographics that are known to have a higher risk of developing dementia. After a four-year follow-up period, vaccinated participants had a 19% incidence of dementia, in contrast to 24% among the unvaccinated group.
Scientists hypothesize that the link may stem from shingles itself, a viral infection causing painful rashes and nerve pain. Contracting shingles has been theorized to increase dementia risk, potentially by triggering neuroinflammation—inflammation of the brain and spinal cord—which is strongly associated with stroke and dementia. Kaleen Hayes, associate director of pharmacoepidemiology at Brown University School of Public Health, which led the study, suggested that the vaccine might prevent this inflammatory pathway by activating the immune system.
While the exact reasons for the observed reduction in dementia risk are not yet fully understood, the findings align with previous research. An October study from Case Western Reserve University reported that the shingles vaccine was associated with a 50% lower risk of vascular dementia and a 25% lower risk of heart attack or stroke in adults aged 50 and over. Previous work has also indicated broader cardiovascular benefits from the vaccine.
Experts not directly involved in the latest study acknowledged its significance. Barak Gaster, director of cognition in primary care at the University of Washington, noted the potential to incorporate this evidence into conversations about vaccine importance, highlighting shingles' painful nature and the added possibility of brain protection. However, others, like David Reuben, MD, professor of geriatrics at the David Geffen School of Medicine, urged caution, stating that the research is still in its early stages and that individual practice should not be altered based on these findings alone.
The study's observational nature means it cannot definitively prove a causal relationship between the vaccine and reduced dementia risk. Nonetheless, the findings contribute to a growing body of evidence suggesting a protective effect. Researchers are planning a large-scale clinical trial in the UK to further investigate this potential link. The shingles vaccine is currently offered by the NHS to individuals aged 65 to 79 and to immunocompromised patients over 18. However, uptake in the UK has been lower than expected, with less than half of eligible individuals over 65 receiving the jab within the first year of its availability.