Annual influenza vaccination may become an accessible strategy for preventing dementia in older adults. This conclusion was reached by Italian researchers. According to them, seasonal flu shots may protect the brain not only from the consequences of infection but also from vascular and inflammatory damage. The study was published in the journal Aging Clinical and Experimental Research (ACER).

Influenza is not only a respiratory infection. The disease is accompanied by pronounced systemic inflammation and increases the risk of cardiovascular complications. Previous studies have shown that during the first week after influenza infection, the risk of myocardial infarction rises sixfold. Strokes and other vascular events, in turn, increase the likelihood of cognitive decline and dementia.

In 2023, a meta-analysis combining data from more than 2 million people showed that vaccinated individuals had a 31% lower risk of developing dementia compared with those who were unvaccinated. Another large study involving nearly 936,000 matched pairs of adults aged over 65 found that vaccination was associated with a 40% reduction in the risk of Alzheimer’s disease over approximately four years of follow-up. The absolute risk reduction was 3.4%, meaning that one case of the disease could potentially be prevented for every 29 vaccinated individuals.

An analysis of data from the U.S. Veterans Health Administration system demonstrated about a 14% reduction in dementia risk. The protective effect was more pronounced among those who received the vaccine regularly over several years. A similar association was identified in a study using the UK Biobank database: the overall risk of dementia was lower (hazard ratio 0.83), while the risk of vascular dementia was even lower (0.58).

The authors highlighted two main possible mechanisms. The first is vascular protection: by preventing influenza, vaccination reduces the likelihood of heart attacks and strokes, thereby limiting cumulative brain damage. The second is an anti-inflammatory effect. Animal experiments show that the influenza virus can activate microglia — the brain’s immune cells — and cause synaptic loss even without direct viral invasion of nervous tissue. Vaccination may potentially reduce such inflammatory surges.

“Influenza vaccination should be considered not only as protection against seasonal infection but also as a possible measure to reduce cardiovascular and cognitive risks,” the researchers noted.

According to the authors, it is especially important to increase vaccination coverage among people over 65 and to use enhanced vaccines designed with age-related immune system changes in mind.