ST. LOUIS — Are older adults who receive both herpes zoster (HZ) and a tetanus, diphtheria, pertussis (Tdap) vaccine less likely to experience cognitive issues than seniors who receive only one or the other vaccine?
That question was addressed in a new study analyzing how receipt of recommended vaccines affects the incidence of dementia in two patients cohorts—the VHA and MarketScan claims data.
Researchers from Saint Louis University School of Medicine and the Harry S. Truman VAMC in Columbia, MO, determined that receipt of HZ alone or Tdap alone, compared with no vaccination, was associated with a statistically significant 25% and 18% lower risk for dementia, respectively.
“Results were robust, and conclusions unchanged after accounting for potential healthy adherer bias, socioeconomic status and results from a negative outcome control analysis,” the authors write in the Journal of the American Geriatric Society.1
They add, “Receipt of both vaccinations was associated with a lower dementia incidence compared with receiving only one type of vaccination and no vaccination, which suggests vaccinations have a common mechanism in the link with incident dementia.”
Background information in the articles points out that multiple types of vaccinations are associated with lower risk for dementia, but it has remained unknown whether receipt of multiple vaccines is associated with an even greater decrease in incident dementia as compared with receiving only one type.
The study concludes that dementia risk is lowest in patients who receive both herpes zoster (HZ) and tetanus, diphtheria, pertussis (Tdap) vaccinations, as compared with receipt of only one or the other type of vaccination.
To conduct the study, researchers replicated primary analysis in a VHA cohort in private sector medical claims data. Considered to be eligible were patients were 65 or older and free of dementia for two years prior to baseline. Records were reviewed for 80,070 veteran patients and 129,200 in the MarketScan data. The mean age for VHA patients was 76.8 ± 7.6 years, with 4.4% female and 90.9% white; in the MarketScan data, patients’ mean age was 70.5 ±5.9, and 65.4% were female.
At index, according to the report, patients either had both HZ and Tdap, only HZ, only Tdap, or neither vaccination. Confounding was controlled with generalized boosted propensity scores and inverse probability of treatment weighting. Competing risk (VHA) and Cox proportional hazard (MarketScan) models estimated the association between vaccination status and incident dementia.
Results indicate that, in both cohorts, having both HZ and Tdap vaccinations compared with no vaccination was significantly associated with lower dementia risk (VHA HR = 0.50; 95% CI: 0.43-0.59; MarketScan HR = 0.58; 95% CI: 0.38-0.89). Also in both cohorts, compared with neither vaccination, patients with only one or the other vaccination types had a significantly lower risk for dementia. Incident dementia was determined to be lower in patients with both vaccinations versus only one vaccination type.
“Receiving two types of vaccinations versus one type was associated with lower dementia risk,” the authors conclude. “Vaccinations may have non-specific associations with incident dementia. Low cost and accessible, common adult vaccinations may be an overlooked intervention for reducing dementia risk.”
- Wiemken TL, Salas J, Morley JE, Hoft DF, Jacobs C, Scherrer JF. Comparison of rates of dementia among older adult recipients of two, one, or no vaccinations. J Am Geriatr Soc. 2021 Dec 12. doi: 10.1111/jgs.17606. Epub ahead of print. PMID: 34897645.
