Study Finds That Flu Vaccine Is Tied To A Lowered Risk Of Alzheimer’s Disease


According to the Centers for Prevention and Disease (CDC), the current estimate for people in the United States with Alzheimer’s disease is around 5.8 million people, with another 200,000 individuals below 65 with younger-onset Alzheimer’s.

Meanwhile, a new study suggests that getting the flu vaccine may actually help lessen the risk of Alzheimer’s disease among older adults, despite not getting inoculated yearly.

This new study looked at 1.87 million adults aged 65 and above without prior history of dementia. Half of these individuals received at least one flu vaccine over a four-year period, while the other half didn’t get any. During the period of the study, the people that got the vaccine were said to be 40% less likely to develop Alzheimer’s disease than those that did not.

The lead study author, Avram Bukhbinder, MD, from the Massachusetts General Hospital in Boston, shared in a statement, “We found that flu vaccination in older adults reduces the risk of developing Alzheimer’s disease for several years.”

Moreover, researchers also discovered that the protective effect of inoculations also showed to increase in step with the total number of annual flu shots that people received during the study.

Dr. Bukhbinder, who did the study while at the John P. and Katherine G. McGovern Medical School at UTHealth in Houston, said, “The rate of developing Alzheimer’s was lowest among those who consistently received the flu vaccine every year.”

Conducting the Study

The team matched people in the study by vaccinated and unvaccinated pairs that were similar in age with similar medical histories, medications, and usage of healthcare visits. At the beginning of the study, the participants were 74 years old on average, with 57% of them female.

The researchers reported in the Journal of Alzheimer’s Disease on June 13 that overall, 5.1% of those who got at least one flu vaccine developed Alzheimer’s disease during their follow-up as compared to the 8.5% of non-vaccinated patients.

One main limitation to the study was that it relied on the data from health insurance claims while only including people who had benefits from both medical care and prescription drugs. The researchers noted that what this meant is that the findings may not apply to individuals with different types of insurance plans.

Although the study was not designed to prove how exactly a flu vaccine may directly help prevent Alzheimer’s disease, it’s still possible that these inoculations could trigger changes in the immune system that may just ward off cognitive decline, suggested the study team.

In addition, a study published in the European Archives of Psychiatry and Clinical Neuroscience in June 2021 shared how infections from the influenza virus and other types of viral infections, such as COVID-19, have also been linked with changes in the central nervous system, which could possibly contribute to cognitive decline.

Other Vaccinations That Are Linked to Lowered Risk of Dementia

The study team also noted that there are various kinds of vaccinations, such as the ones for herpes, tetanus, polio, and influenza, that have been associated with a decreased risk of dementia before.

But according to Dr. Bukhbinder, one open-ended question is whether the COVID-19 vaccine may also be linked to a reduced risk of Alzheimer’s disease. However, more research is needed to determine the true impact of vaccinations on people that have already been diagnosed with Alzheimer’s disease.

Dr. Bukhbinder pointed out, “Future research should also assess whether flu vaccination is also associated with the rate of symptom progression in patients who already have Alzheimer’s dementia.”