[Two studies] have demonstrated that flu and pneumococcal vaccines are linked with a lower risk of Alzheimer’s disease.
In both studies, individuals who had received at least one vaccination—a flu shot in one study, and a pneumonia vaccine with or without a flu shot in the second—were less likely to be diagnosed with Alzheimer’s later in life. While the studies are slightly different, their similar conclusions suggest that vaccines may play a broader role in strengthening a person’s lifelong resistance to some diseases.
Both teams are working to determine the biological mechanisms that explain their findings, but they do have some preliminary thoughts. [Geneticist Svetlana] Ukraintseva, speaking to MedPage Today, proposes that because so many different types of pathogens have been implicated in Alzheimer’s, including viruses, bacteria, and fungi, vaccines could provide benefits simply by keeping people protected from the more general wear and tear of life.
[B]ecause both the flu and pneumonia are known to have effects on the brain, reducing the amount of times one is exposed to them over the course of a life would keep the immune systems primed and protective for longer. Maria Carrillo, chief science officer of the Alzheimer’s Association who was not involved in either study, tells NPR, “every time you have one of these infections you may experience a challenge to your memory and thinking.”