Influenza vaccination may be associated with a reduced risk of developing Alzheimer disease (AD), according to new findings presented at the Alzheimer’s Association International Conference.

“Analysis of a large clinical database suggests that there is a strong inverse relationship between AD and influenza vaccination,” the authors of the study wrote. “This result provides evidence that influenza vaccination may be a confounding factor in epidemiological studies of risk factors of Alzheimer Disease,” they added.

The authors arrived at their conclusion after examining data from the Cerner Health Fact EHR dataset that included 311,424 patients with clinically diagnosed AD. Patients aged less than 60 years were excluded. Ultimately, through propensity score matching, the researchers achieved a balanced data set of 9066 vaccinated and unvaccinated patients with propensity score matching.

The researchers divided the number of vaccinations by the length of time from first vaccination to AD onset or end of observation in order to determine the impact of vaccination frequency on AD risk. They also performed a survival analysis for all patients, with development of AD as the end outcome.

The results of the study indicated that influenza vaccination is associated with a significantly decreased prevalence of AD (odds ratio [OR] 0.8309). In addition, the researchers found that the frequency of influenza vaccination was significantly associated with inhibited AD onset (OR 0.8736).

Findings from a time-to-event analysis demonstrated that influenza vaccination at an earlier age is associated with a lower risk of AD compared with vaccination at an older age. The hazard rate was found to increase by 1.0924 with each yearly increase in age of first influenza vaccination.

“Future studies may shed light on biological mechanisms to more deeply understand a promising, readily available candidate for preventing AD,” the researchers concluded.

—Christina Vogt

Reference:
Amran A, Bukhbinder A, Ramesh S, et al. Influenza vaccination is associated with a reduced incidence of Alzheimer’s disease. Paper presented at: Alzheimer’s Association International Conference; July 27-31, 2020; Virtual. https://www.alz.org/aaic/downloads2020/AAIC2020-Vaccines.pdf