Shingles Vaccine Linked to a Significant Decline in Dementia-Related Deaths
A recent study reveals a compelling connection between the shingles vaccine and a dramatic reduction in dementia-related deaths. The research, conducted in Wales, highlights the potential of zoster vaccination to slow the progression of dementia.
The findings, presented at the Clinical Trials on Alzheimer's Disease (CTAD) meeting, indicate that individuals with dementia who received the live-attenuated zoster vaccine experienced a remarkable 29.5 percentage point decrease in dementia-related deaths over a 9-year period. This is a significant finding, as it suggests that the vaccine may have a therapeutic effect on dementia, potentially averting deaths and reducing mortality rates.
Furthermore, the study found that zoster vaccination was associated with a 3.1 percentage point decrease in mild cognitive impairment cases during the same period. This suggests that the vaccine not only benefits those with dementia but also has a positive impact on cognitive health in general.
The research, led by Dr. Pascal Geldsetzer, builds upon previous studies. In a Nature study, Geldsetzer and his team discovered that shingles vaccination reduced the risk of developing dementia by 3.5 percentage points over 7 years, with a stronger protective effect in women. This finding, combined with the current study, suggests that the vaccine may have a dual benefit, preventing or delaying dementia and improving outcomes for those already affected.
The unique vaccine eligibility criteria in Wales played a crucial role in the study. People born before September 2, 1933, were ineligible for the vaccine, while those born on or after that date became eligible after the vaccination program began in 2013. This allowed researchers to compare two groups with similar characteristics, removing selection bias and strengthening the study's conclusions.
Additional research supports the link between shingles vaccines and dementia. A 2024 study involving 200,000 older adults in the U.S. found that the recombinant subunit zoster vaccine (Shingrix) was associated with a larger reduction in dementia risk compared to the live zoster vaccine. Furthermore, a study this year involving over 400,000 U.S. patients suggested that AS01-adjuvanted vaccines for respiratory syncytial virus and recombinant zoster vaccines may reduce dementia incidence, indicating a potential role for the adjuvant.
The CTAD study utilized data from the SAIL Databank and focused on two groups of adults born near the 1933 eligibility cutoff. The findings revealed that among those without baseline cognitive impairment, 7.3% developed mild cognitive impairment over 9 years, while in the dementia group, 49.1% died with dementia recorded as the underlying cause.
Dr. Geldsetzer emphasized the vaccine's potential therapeutic benefits, stating that it may not only prevent deaths from dementia but also reduce mortality among individuals already affected by the condition. The study also noted that the protective effects of zoster vaccination were more pronounced in women than in men.
While the study primarily assessed the live-attenuated zoster vaccine, it's important to note that the recombinant zoster vaccine is available in many countries, including the U.S. The CDC recommends this vaccine for healthy adults aged 50 and older or individuals with weakened immune systems aged 19 and up.
However, the analysis had limitations, as it focused on individuals born near the 1933 threshold and may not be applicable to younger age groups. The researchers relied on electronic health records and death certificates for data, which may have influenced the study's scope.
Dr. Geldsetzer is currently raising funds for a randomized controlled trial to further investigate the relationship between live-attenuated shingles vaccines and dementia. He believes that a positive outcome would have significant implications for clinical medicine, population health, and dementia research.
