Results reported at the Alzheimer Association International Conference (AAIC) 2020 showed vaccinations for the flu and pneumonia may reduce the incidence of Alzheimer disease (AD).
In a study of health records from 9,066 people, having a flu vaccination was associated with a lower prevalence of AD (odds ratio 0.83, p <0.0001). Receiving the flu vaccine more frequently was associated with an even lower prevalence of AD (odds ratio 0.87, P=0.0342). The study concluded that patients between the ages of 75 and 84 years who consistently got their annual flu shot had a nearly 6% reduced risk of AD.
The protective association between the flu vaccine and the risk of AD was strongest for those who received their first vaccine at a younger age. Those who received their first flu shot at age 60 benefitted more than those who received their first shot at age 70.
In another study, researchers examined the association between pneumococcal vaccination, with and without an accompanying seasonal flu shot, and the risk of AD among 5,146 participants age 65 years or more from the Cardiovascular Health Study.
In this study, the rs2075650 G allele in the TOMM40 gene was taken into account as a known genetic risk factor for AD. After adjusting for gender, race, birth cohort, education, smoking, and number of G alleles, people who had the pneumococcal vaccination between age 65 and 75 were 25%-30% less likely to have developed AD by . The total number of vaccinations for pneumonia and the flu between age 65 and 75 was associated with a lower risk of AD; however, in this study, the effect was not evident for the flu shot alone.
Individuals with dementia commonly experience viral, bacterial, and other infections. In a third study using records from approximately 1.5 million Danish residents over age 65, it was shown that hospitalized individuals with either infection or dementia were 6.5 times more likely to die than those without both conditions. Dementia or infection alone increase the rate of mortality threefold.
Together these studies show a strong protective effect of flu and pneumonia vaccinations against risk for and of dementia.