- The World Health Organization estimates that more than 55 million individuals worldwide have Alzheimer’s disease or another form of dementia, and that 10 million new cases are diagnosed each year.
- More research is being done on vaccines as a potential method for lowering the risk of Alzheimer’s disease.
- The mechanism behind the flu vaccine’s potential to cut this risk by 40% is yet unknown, according to a recent study.
Alzheimer’s disease cases are on the rise, but it has remained difficult to pinpoint why some people get this type of dementia and others don’t.
According to research, there are many different risk factors, including genetics, lifestyle, and environmental variables. How our immune system may impact our risk of getting Alzheimer’s disease is one area that has not garnered much research until relatively recently.
Recent studies have indicated that certain vaccinations, such as the BCG, a tuberculosis vaccine, and the chicken pox/shingles vaccine, may lower the chance of acquiring Alzheimer’s disease.
The flu vaccine may be protective, according to recent research, although it is unclear if the shots themselves affect risk or just whether preventing an infection does.
The Journal of Alzheimer’s Disease reported these findings.
looking into the connection
A team from The University of Texas Health Science Center in Housten, Texas, set out to look at the relationship between flu vaccines and the risk of dementia specific to Alzheimer’s disease based on prior research that suggests vaccines lessen the risk of dementia.
They formed two groups, each consisting of 935,887 patients, using historical claims data from patients 65 years of age or older who were dementia-free over the 6-year look-back period. While the second group did not receive the flu shot, the first group did. Regarding baseline demographics, medications, and comorbidities, the groups were matched.
The research found that throughout a 4-year follow-up period, people who had at least one flu shot were 40% less likely than those who hadn’t to acquire Alzheimer’s disease. Patients who had gotten a flu shot each year for the previous six years had the lowest risk.
According to other studies, at least six flu shots are required to lower the risk of Alzheimer’s disease, according to lead author Dr. Avram Bukhbinder, who spoke to Medical News Today. For this reason, the researchers utilized a look-back period of six years. He said that they had updated their data analysis to consider the impact across 4, 6, and 8 years.
When the look-back period was increased from 4 to 8 years, influenza vaccination had a similar impact on Alzheimer’s risk, he said.
He continued, “I wasn’t too surprised to find a similar result in this broader population of older adults in the U.S. because previous studies of patients with serious chronic illnesses (such as chronic kidney disease) and of veterans have found an association between influenza vaccination and risk of dementia.
Dr. Nicola Veronese, a senior researcher in geriatrics and internal medicine at the University of Palermo in Italy, echoed his opinions last year after conducting a meta-analysis of five studies that examined the relationship between influenza vaccination and the risk of developing Alzheimer’s disease.
In an interview with MNT, he stated that the report was supportive of earlier studies and applauded the size of the cohort employed.
As a teacher speaking, I thought this paper was confirmed and was really well written. He said this subject might lead to more concrete data about how influenza vaccinations affect illnesses and dementia in general.
A yet elusive mechanism
However, it is too soon to advise receiving the flu shot to lower the risk of Alzheimer’s disease, according to Dr. Heather M. Snyder, vice president of medical and scientific affairs for the Alzheimer’s Association.
“More research is needed to understand the biological mechanisms behind the results in this study. For example, it is possible that people who are getting vaccinated also take better care of their health in other ways, and these things add up to a lower risk of Alzheimer’s and other dementias.”
— Dr. Heather M. Snyder
She continued, “It is also plausible that there are problems with unequal access and/or vaccine reluctance and how this may affect the study population and the research findings.
The authors speculate that flu shots might affect our innate immune system.
Vaccinations against the flu and other diseases “are associated with non-specific protective benefits via long-term reprogramming of innate immune cells,” they say. This might affect how the body gets rid of the chemical that accumulates in the brain and causes diseases like Alzheimer’s or inflammatory reactions.
Another explanation for the results is that they point to a potential age-related interaction between the adaptive immune system and vaccination.
This claim, according to Dr. Veronese, is “more theoretical than practical.”
He continued, “We do not have any direct data demonstrating the alteration in adaptive secondary or primary immune system.