Research comparing Welsh residents born on either side of September 2, 1933, focused on their engagement with preventative health services, past health diagnoses, and educational attainment. The study assessed dementia rates between these groups, with an initial confirmation that the shingles vaccine proved effective in lowering the incidence of the condition, yielding results consistent with findings from earlier clinical trials.
The findings indicate that eligibility for the vaccine correlates with a 1.3 percent decrease in the absolute risk of being diagnosed with dementia. When assessed in relative terms, this represents an 8.5 percent reduction in relative risk. It is noteworthy that, with fewer than half of eligible individuals receiving the vaccine, the overall relative risk reduction approximates 20 percent—an impressive figure.
To validate these results, researchers utilized a difference-in-difference analytical method, yielding similar outcomes and ruling out the chance that individuals seeking healthcare for shingles or other ailments were more likely to receive a dementia diagnosis. A comparison of health outcomes between pre-vaccine and post-vaccine populations revealed no significant changes, and no adjustments to NHS policy were made in relation to the September 2 cut-off date.
In an additional study shared on the Med arXiv platform, researchers unearthed comparable findings using data from the UK’s NHS, indicating a potential protective effect of the shingles vaccine against mortality associated with dementia. The consistency of these outcomes suggests a credible effect.
Understanding the Mechanism
The researchers propose three possible explanations for these findings. The most straightforward is the notion that preventing the reactivation of the varicella zoster virus directly mitigates the risk of dementia. Another possibility is that the vaccine may have an indirect impact—modifying immune system responses linked to dementia. Finally, there is the speculative idea that treatment for shingles might inadvertently influence the onset of dementia or increase the likelihood of such diagnoses.
