An analysis of data from nearly 200 people aged 65 and over found that a high dose of flu vaccine was associated with a lower risk of Alzheimer's, especially in women. * The researchers emphasize that this is a correlation that was discovered in clinical findings and the reason still needs to be examined.
A new study by researchers at UTHealth Houston raises an intriguing possibility: Not only may getting the flu vaccine be associated with a reduced risk of Alzheimer's disease, but the strength of the dose may also matter. According to the study, published in the journal Neurology, people aged 65 and older who received a high-dose flu vaccine had a lower risk of developing Alzheimer's than their peers who received the standard dose.
Alzheimer's is the leading cause of dementia, and according to the data cited in the study, more than seven million Americans aged 65 and over were living with the disease in 2025. This is about one in nine people in this age group, and projections speak of more than doubling by 2050. Against this background, any hint of a factor that might reduce the risk of the disease attracts a lot of attention.
The new study also builds on previous work from the same research center. In 2022, the group led by Prof. Paul Schultz reported that among people aged 65 and older, getting the flu vaccine was linked to a 40% reduction in the risk of Alzheimer’s. Now the researchers are trying to find out if there is a difference between the types of doses, after public health officials asked whether the high dose, sometimes given to older people, changes the picture.
What did the study find?
Researchers analyzed data from nearly 200 adults aged 65 and older, both men and women, and compared those who received a high-dose flu vaccine with those who received the standard dose. The findings showed that the group that received the high dose had a lower risk of Alzheimer's. The protective effect was more pronounced in women.
According to the report, while the standard dose of the flu vaccine has previously been linked to a 40% reduction in the risk of Alzheimer's, the high dose was linked to a nearly 55% reduction in risk among those aged 65 and older. This is a significant gap, which may indicate that the strength of the immune response also affects mechanisms related to brain health, although at this point the researchers do not claim to have directly proven such a mechanism.
Why is there a high dose at all?
As we age, our immune systems become less effective at fighting off infections. For this reason, the U.S. Centers for Disease Control and Prevention (CDC) recommends that people 65 and older get a high-dose flu vaccine, which is four times stronger than the standard version given to the general public. However, the boosted vaccine is not widely available, so some older adults still get the standard dose.
The practical significance of the study is still cautious. This is a broad analysis of real-world data, not a randomized controlled trial designed to test Alzheimer's prevention. Therefore, it is more accurate to say that the study found a strong association between high-dose flu vaccination and a decreased risk of the disease, rather than that the vaccine itself has been proven to prevent it. Still, given the ongoing increase in the prevalence of Alzheimer's and the fact that it is a well-known, available, and routine medical measure, the findings are expected to arouse great interest and spur further research.
If the findings are confirmed in further studies, it is possible that in the future high-dose flu vaccination will be seen not only as a tool for protecting against flu complications in older adults, but also as part of the broader discussion about reducing the risk of degenerative brain diseases. For now, the study adds an important layer to a hypothesis that has already been strengthened in recent years: high-dose flu vaccination may also be associated with better cognitive health in older adults.
for the scientific article DOI: 10.1212/WNL.0000000000214782
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