flu vaccination

by Dr. Noel Peterson, ND, DAAPM

What is the most feared disease in America?

Cancer? Stroke? Heart disease?

No, it turns out that Alzheimer’s disease (aka dementia) is the most feared disease in America.

What if you could reduce the risk of Alzheimer’s by over 40% with a simple flu vaccination? Reporting In the June 2022 issue of the Journal of Alzheimer’s Disease, researchers from the University of Texas School of Public Health  compared the incidence of Alzheimer’s Disease (AD) in  935,887 matched pairs of flu-vaccinated and unvaccinated individuals (1,871,774 total patients) who had not experienced dementia during the preceding six years and had not yet turned 65 at the beginning of the follow-up. They found that even a single flu vaccination reduced the risk of AD by 40%,They also observed that yearly vaccination continued to reduce AD incidence during the 6 year follow-up.

The greater the number of flu vaccinations a patient had, the greater the reduction in Alzheimer’s

Furthermore, the greater the number of flu vaccinations a patient had during the 4-year followup, the greater the reduction in AD. Up to 6 vaccinations were followed, and reduction reached over 50% at 48 months. Researchers observed a declining AD protection after 4 years since the last flu vaccination.

How does flu vaccination protect against Alzheimer’s Disease?

We know that during influenza infection, injury to the brain can occur from direct viral invasion of nervous tissues and as collateral damage from our systemic immune response to influenza infection. Neurologic complications commonly manifest as headache, encephalopathy, demyelination, and long-term neuropsychiatric sequelae such as depression and persistent cognitive impairment.

Further research is needed to understand the mechanisms underlying the apparent protective benefits of influenza vaccination on AD risk. These mechanisms—as well as those underlying the effects of other adulthood vaccinations on the risk of all-cause dementia—can be divided into at least three broad, non-exclusive categories: 1) influenza-specific mechanisms, such as mitigating the harm caused by influenza infection; 2) non-influenza-specific training of the innate immune system and 3) non-influenza-specific changes in adaptive immunity.

Flu vaccination reduces “inflammaging”

One innate immunity-related mechanism may be that flu vaccination reduces the sustained low-grade systemic elevation of disease causing proinflammatory cytokines known as “inflammaging.” The brain’s microglia cells are critical to the regulation of brain inflammaging, and also for the removal of AD causing  amyloid beta plaques from the brain. It has been shown that vaccination can enhance the removal of these plaques by our microglia.

Several other adult vaccinations are associated with lower risk of dementia

Regardless of the exact mechanism, the growing body of evidence suggests that other adulthood vaccines (including those for tetanus and diphtheria, zoster, and tuberculosis) are associated with a lower risk of developing dementia.

What about flu vaccination and the risk of stroke?

Researchers at the University of Calgary reported in The Lancet Public Health  that  the flu vaccine reduced the risk of stroke among all adults by around 25%, even in individuals who are not at high risk for stroke. Investigators evaluated the health records of over four million Albertans over a nine-year period and found that vaccination lowered the risk of stroke by 22-26% for at least 6 months following vaccination.

Is the flu vaccine safe?

Ok, so vaccination reduces the risk of AD, but is it safe? Hundreds of millions of Americans have safely received flu vaccines over the past 50 years, and there has been extensive research and side effect surveillance supporting the safety of flu vaccines. Information on vaccine safety and more can be found on the CDC influenza information site here.

According to the CDC, During the 2018–2019 flu season, adults aged ≥ 65 constituted 57% of influenza-related hospitalizations and 75% of influenza-related deaths. Vaccination reduced the risk of being admitted to an ICU with flu by 82%.

One more thought about reducing the risk of Alzheimer’s: Get your COVID vaccination. From what we have seen, Long COVID is very hard on people’s brains, and my guess is that we will see a decrease in AD in those that got their COVID vaccine and boosters, and therefore either did not come down with, or had milder cases of COVID. I took my flu vaccination in my right shoulder at the same time as my COVID booster in the left arm. Oh boy! Did I have a 12 hour case of what felt like the flu. So maybe it’s best to have them on separate days? With the added benefit of reducing your risk of Alzheimer’s Disease by 40% or more, isn’t it time you got your flu vaccine?