In three new studies, researchers found Flu (influenza) and pneumonia vaccinations are linked to a reduced risk of Alzheimer’s disease.
The research was conducted by a team at The University of Texas Health Science Center at Houston and elsewhere.
Previous research has suggested vaccinations may have a protective factor against cognitive decline, but there have been no large, comprehensive studies focused on influenza (flu) vaccine and Alzheimer’s disease risk, specifically.
In one study, the researchers found at least one flu vaccination was linked to a 17% reduction in Alzheimer’s incidence.
More frequent flu vaccination was linked to another 13% reduction in Alzheimer’s incidence.
Vaccination against pneumonia between ages 65 and 75 reduced Alzheimer’s risk by up to 40% depending on individual genes.
People with dementia have a higher risk of dying (6-fold) after infections than those without dementia (3-fold).
In addition, the team found the protective association between the flu vaccine and the risk of Alzheimer’s was strongest for those who received their first vaccine at a younger age, for example, the people who received their first documented flu shot at age 60 benefitted more than those who received their first flu shot at age 70.
The findings suggest that regular use of a very accessible and relatively cheap intervention—the flu shot—may significantly reduce the risk of Alzheimer’s dementia.
In the second study, a team at Duke University tested associations between pneumococcal vaccination, with and without an accompanying seasonal flu shot, and the risk of Alzheimer’s disease.
The researchers found that pneumococcal vaccination between ages 65-75 reduced the risk of developing Alzheimer’s by 25-30%.
The largest reduction in the risk of Alzheimer’s (up to 40%) was observed among people vaccinated against pneumonia who were non-carriers of the Alzheimer’s risk gene.
The total number of vaccinations against pneumonia and the flu between ages 65 and 75 was also linked to a lower risk of Alzheimer’s; however, the effect was not evident for the flu shot alone.
In the third study, a team from the University of Copenhagen found that people with both dementia and such hospital visits died at 6.5 times higher rate compared with people who had neither.
Study participants with either dementia alone or infection-related contacts alone had a threefold increased rate. The rate of mortality was highest within the first 30 days following the hospital visit.
The researchers also found that for people living with dementia the mortality rates remained elevated for 10 years after the initial infection-related hospital visit, and mortality rates from all infections (including major infections like sepsis to minor ear infections) were higher compared with people without dementia or without an infection-related hospital visit.
The study findings were presented at the Alzheimer’s Association International Conference (AAIC) 2020.
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