Influenza and pneumonia vaccination may be protective against the development of Alzheimer disease (AD) in older patients, according to new research presented at the Alzheimer’s Association International Conference (AAIC) 2020 in Chicago, Illinois.

Although some evidence suggests that vaccines may protect against cognitive decline, no comprehensive studies have specifically assessed the association between influenza or pneumonia vaccination and AD risk. At AAIC 2020, 2 presentations separately discussed observing a reduced risk of AD in patients who received the influenza and pneumonia vaccines.

In order to assess whether influenza vaccination affects AD prevention, a team out of The University of Texas Health Science Center in Houston obtained health records of 9066 vaccinated and unvaccinated patients. “To analyze the effects of frequency of vaccination, we divided the number of vaccinations by the length of time from the first vaccination timestamp to AD onset or the end of the observation,” the authors explained. Survival analysis was performed for the entire cohort and AD development was considered the end outcome.

Findings of the analysis revealed a “strong inverse relationship” between receiving the influenza vaccine and AD. Results of the study not only showed that influenza vaccination significantly decreased the prevalence of AD (odds ratio [OR], 0.8309; P <.0001), but that the frequency of receiving the vaccine had a “significant impact to inhibit AD onset” as well (OR, 0.8736; P =.0342). Findings of the analysis determined that receiving the influenza vaccine at a younger age was associated with a smaller AD risk compared to receiving it at an older age (ie, a hazard ratio increase of 1.0924 was observed when the age of first vaccination increased by 1; P <.0001).

In the second presentation, a team out of the Duke University Social Science Research Institute analyzed the association between pneumococcal vaccination, with or without an accompanying influenza vaccine, and AD risk. A total of 5146 patients >65 years old from the Cardiovascular Health Study were included in the analysis and a known AD genetic risk factor (the rs2075650 G allele in the TOMM40 gene) was taken into account.

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Findings of this analysis revealed an association between pneumonia vaccination between 65 and 75 years old and a reduced risk of AD afterwards (OR, 0.70; P <.04). Additionally, patients who were vaccinated against pneumonia that were non-carriers of the rs2075650 G allele, which is a risk factor for AD, were found to have the largest reduction in AD risk (OR, 0.62; P <.04). The researchers also reported, “Total count of vaccinations against pneumonia and the flu between ages 65 and 75 was also associated with a lower risk of AD occurrence later in life (OR = 0.88; P<0.01); however, the effect was not seen for the flu alone.”

While this research is promising, additional large-scale clinical trials are necessary to assess whether vaccines can be used as a public health strategy to decrease the risk of AD and dementia.

References:

  1. Amran A. Influenza vaccination is associated with a reduced incidence of Alzheimer’s disease. Paper presented at: Alzheimer’s International Conference 2020; July 27, 2020; Chicago, IL.
  2. Ukraintseva, S. Repurposing of existing vaccines for personalized prevention of Alzheimer’s disease: Vaccination against pneumonia may reduce AD risk depending on genotype. Paper presented at: Alzheimer’s International Conference 2020; July 27, 2020; Chicago, IL.