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New Research Suggests Shingles Vaccine May Lower Dementia Risk

Recent studies in Wales have investigated the relationship between shingles vaccination and the incidence of dementia among residents born on either side of a significant cutoff date: September 2, 1933. By matching individuals based on their use of preventive health services, prior health diagnoses, and levels of education, researchers were able to draw comparisons regarding dementia occurrence related to their vaccination status.

The findings confirmed that the shingles vaccine effectively reduces the number of cases, echoing results from earlier clinical trials. More notably, being eligible for the vaccine correlated with a 1.3 percent decrease in the absolute risk of receiving a dementia diagnosis. This reduction equates to an 8.5 percent decrease in relative risk. However, with less than half of those eligible having received the vaccine, the adjusted figures suggest a more substantial relative risk reduction of 20 percent, highlighting the vaccine’s potential significance.

To validate their findings, the researchers employed a difference-in-difference analysis, which produced similar results. This approach helps ensure that the association between vaccination and dementia diagnoses is not merely a byproduct of increased healthcare engagement among those diagnosed with shingles. Furthermore, the analysis compared health outcomes before and after the vaccination cutoff and found no other relevant changes within the two populations, indicating that NHS policies remained stable during this period.

In a related draft manuscript shared on Med arXiv, researchers also observed a similar protective effect of shingles vaccines when linked to mortality rates attributed to dementia, reinforcing the credibility of their findings.

Possible Explanations for the Findings

Researchers have proposed three potential mechanisms to explain the observed reduction in dementia risk associated with shingles vaccination. The most straightforward explanation is that the vaccine directly mitigates the reactivation of the varicella zoster virus, which could, in turn, delay or reduce the onset of dementia.

Alternatively, they suggest that the relationship might be indirect. It is possible that dementia is connected to immune system activity, and the vaccine may alter this dynamic in some beneficial way. Lastly, it is worth considering whether treatment for shingles could inadvertently raise the likelihood of developing dementia or intensify diagnosis rates due to increased medical attention.

Source
arstechnica.com