Shingles Vaccination Linked to Lower Dementia Risk in Older Adults, suggests study
Researchers have found in a cohort study using target trial emulation that older adults, particularly those in skilled-nursing facilities, were less likely to receive a dementia diagnosis if they had been vaccinated against herpes zoster (shingles). The findings are consistent with previous studies conducted in other countries, suggesting a potential association between shingles vaccination and a reduced risk of dementia. However, researchers cautioned that factors such as residual confounding and the “healthy vaccinee” effect may have influenced the results, so a direct causal relationship cannot yet be confirmed. The study was published in the Annals of Internal Medicine by Kaleen N. and colleagues.
Data were obtained from a comprehensive set of Medicare fee-for-service claims data seamlessly linked with electronic health record data collected from skilled-nursing facilities in the US. In particular, the study considered patients aged 66 years and above that were newly enrolled into a skilled-nursing facility for either post-acute or long-term care purposes from January 1, 2017, to December 31, 2022. Only patients without any previous history of dementia diagnosis and eligible for receiving the recombinant zoster vaccine (RZV) were considered for inclusion in the study. The treatment group was determined by administering one or more doses of RZV in the facility or within a period of 12 months after the patient's first admission to the facility if he/she got discharged before that period. In order to control for the complexity associated with the timing bias regarding vaccination, the researchers used a very sophisticated "clone-censor-weight" statistical approach.
Key findings:
- The target trial emulation approach was able to identify a national sample of 509,926 eligible patients without dementia at baseline.
- In the total population, a selected group of 8,843 patients (1.73%) received at least one dose of the RZV within 12 months following their first skilled nursing facility admission.
- Among this group, the overwhelming majority, precisely 87.0% of subjects, received their doses of the vaccine after discharge from the skilled nursing facility.
- Administration of the recombinant vaccine was found to decrease the absolute risk of dementia by 5.8 percentage points within a period of 4 years (95% CI, 3.9 to 7.5 percentage points lower).
- Statistical results revealed a strong risk ratio coefficient of 0.76 (95% CI, 0.69 to 0.84) in favor of the vaccination group.
- The overall risk of dementia within a period of 4 years was decreased to 18.8% within a group that was given at least one RZV dose, as opposed to 24.6% in the control group.
- The effect of the vaccine was significantly weaker among male patients and patients who previously used the older live-attenuated herpes zoster vaccine.
Overall, the administration of RZV either while admitted to a skilled nursing facility or within one year was found to be associated with a reduced risk of developing dementia. These powerful findings from the target trial simulation study offer an essential empirical basis for longevity medicine in the contemporary world, indicating the potential use of targeted viral prevention as an extremely effective approach.
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