Regular vaccination against influenza seems to protect against dementia. In Germany alone, that could make a difference for 40,000 people a year.

A current study supports an exciting hypothesis: According to this, regular flu vaccinations could lead to a lower risk of dementia. A large population consisting of over 120,000 US veterans with an average age of 75.5 years (± 7.3) was examined. Only 3.8% were female, 91.6% had a white skin color. The medical files of the study participants were analyzed between September 1, 2009 and August 31, 2019. The inclusion criterion was that the patients included in the analysis had no diagnosis of dementia two years before the start of the study and at the time of inclusion in the study.

Dementia: effects of covariates not taken into account

The subjects were then classified into groups depending on whether and how many flu vaccinations they had received during the study period. It was then analyzed in how many people newly developed dementia (defined according to the existence of the corresponding ICD-9 / ICD-10 codes in the medical records over the course of time). The effect of covariates such as age, ethnicity, gender, marital status and insurance status – all factors that influence the risk of dementia – were factored out, and the frequency of doctor visits was also analyzed in order to reduce possible early detection bias.

Overall, the median observation period was 80 months for the vaccinated and 81 months for the unvaccinated. 15,933 study participants developed dementia during this phase. The analysis showed that the use of flu vaccinations was associated with a lower risk of dementia. However, the effect only came to bear if a total of more than six flu vaccinations were administered within the observation period. In this survey, the risk of dementia was significantly reduced by the vaccinations by 12 percent (HR: 0.88).

Influenza vaccination: save 40,000 Germans from dementia every year

“This effect is not insignificant. With around 330,000 new cases of dementia in Germany every year, regular flu vaccinations could save almost 40,000 people from being diagnosed with dementia every year. However, it must be emphasized that this is a retrospective evaluation, one with a high number of study participants and careful implementation, but that it is not of evidence but can only show an association. Several such association studies are already available, not only on flu vaccinations, but also on vaccinations against diphtheria or tetanus. Experimental studies have also indicated a connection between vaccinations and a lower risk of dementia. The hypothesis generated by the current study can therefore also be substantiated pathophysiologically, flanked by data from animal experiments, ”explains DGN dementia expert Prof. Richard Dodel, Essen.

Vaccination increases the activity of the microglia

Put simply, the authors explain this as follows: The vaccinations lead to an increase in the activity of microglia, the brain’s immune cells, so to speak. They recognize disease-causing substances and waste products and break them down. Animal experiments have shown that the increased microglial activity after vaccination leads to beta-amyloid being broken down more. In Alzheimer’s disease, beta-amyloid accumulates, is deposited there between the nerve cells like a coating and damages the nerve cells.

“The basic idea of ​​many Alzheimer’s therapies is to smuggle beta-amyloid out of the body before the protein can cause damage to the brain. If prospective studies now show that repeated flu vaccinations have exactly this effect and break down beta-amyloid, that would be a breakthrough for dementia therapy. The available data suggest this, but are not yet conclusive. The observed positive effect of vaccinations on the risk of dementia could ultimately also be due to the fact that people who receive regular vaccinations also live more healthily and thus have a lower risk of illness. We therefore now need further, prospective studies to unambiguously clarify the connection, ”is Dodel’s conclusion.

Vaccinations: Don’t just discuss risks

“There is currently a lot of discussion about the potential risks of vaccinations, in general, but especially with regard to vaccination against SARS-CoV-2. But there are not only potential risks, there are also potential additional benefits of vaccination that have so far not been mentioned in the discussions. For an informed decision, everything should be considered if possible, ”emphasizes DGN General Secretary Prof. Peter Berlit.

This article is based on a press release by the DGN. We have linked the study here and in the text.

Image source: Robina Weermeijer, unsplash