New Study Suggests Shingles Vaccine May Slow Cognitive Decline
A follow-up study indicates the vaccine may have not only preventive but also therapeutic potential against dementia, reducing the risk of mortality in those already diagnosed
A new follow-up study, published in the journal Cell, adds evidence that the shingles vaccine, a two-dose shot recommended for adults 50 and older to protect against the painful viral infection, may offer benefits beyond typical prevention.
The research suggests the vaccine could possess therapeutic properties against dementia by slowing the progression of the disease, leading to a reduced risk of dying from the condition.
Preventive and Therapeutic Potential
Dr. Pascal Geldsetzer, assistant professor of medicine at Stanford University and senior author of the new study, called the finding unexpected and exciting. He noted: “That means that the vaccine doesn’t just have a preventive potential, but actually a therapeutic potential as a treatment, because we see some benefits already among those who have dementia.”
This new research builds upon a previous study by the same team, which had already found evidence that shingles vaccination may offer a “dementia-preventing” or “dementia-delaying” effect.
Unique Study Design
Both studies analyzed the health records of over 282,500 older adults in Wales, where a shingles vaccination program was introduced in September 2013. The program had unique age-eligibility rules: people who were 79 were eligible for the vaccine for one year, while those 80 or older were not.
This minimal difference in age allowed researchers to compare two groups who should be largely similar in all other characteristics (physical activity, diets, etc.), differing only in the probability of being vaccinated. This design helps researchers be more confident that the link observed represents a cause-and-effect relationship rather than mere correlation. The researchers also analyzed similar health records in Australia to strengthen their findings.
Key Findings
-
Reduced Mild Cognitive Impairment (MCI): Among older adults with no prior record of cognitive impairment, those who received the shingles vaccine saw a 3.1 percentage point reduction in their risk of being newly diagnosed with MCI over a nine-year period, compared to the unvaccinated group. This protective effect appeared stronger in women.
-
Reduced Mortality Risk: Among older adults already living with dementia, those who received the shingles vaccine experienced a 29.5 percentage point drop in their risk of dying due to the disease over a nine-year period, suggesting the vaccine may play a role in slowing dementia progression.
Potential Mechanisms
While the study did not pinpoint the exact mechanism, Dr. Geldsetzer offered two main theories:
-
Reduced Inflammation: The virus that causes shingles (varicella-zoster) remains dormant in the nervous system, and its reactivation causes constant interaction with the immune system and leads to inflammation. Since inflammation is a key process in dementia, reducing these reactivations through vaccination might offer benefits.
-
Overall Immune System Boost: The vaccine may provide a broad boost to the immune system, strengthening the body’s ability to fight off infections in general. A growing body of research links various infections to increased dementia risk, so a stronger immune response could help lower that risk.
Evaluation and Next Steps
Other scientists view the study as a crucial advance, as it provides the closest to causal evidence possible for the shingles vaccine’s benefits.
However, experts note that the findings may not generalize to newer, more widely used vaccines and stress the need for future mechanistic studies and a randomized clinical trial to “conclusively test” this link before vaccination can be recommended solely for the purpose of dementia risk reduction.
Source: https://edition.cnn.com/2025/12/02/health/shingles-vaccine-dementia-progression-study-wellness
