High-Dose Flu Vaccine Reduces Alzheimer’s Risk in Older Adults

A high-dose influenza vaccine is associated with a significantly lower risk of Alzheimer’s disease in adults aged 65 and older compared to standard-dose vaccines, according to a retrospective cohort study published in the journal Neurology.

Researchers led by a team at the McGovern Medical School at UTHealth in Houston analyzed health data from approximately 165,000 older adults. The study found that the high-dose flu vaccine reduced the risk of Alzheimer’s disease by nearly 55% over a period of roughly two years.

Comparison With Standard-Dose Vaccines

The study compared nearly 121,000 seniors who received the high-dose flu shot with more than 44,000 who received the standard dose. While the high-dose version showed a nearly 55% reduction in risk, previous research by the same team indicated that the standard-dose vaccine was linked to a 40% reduced risk of developing Alzheimer’s over a four-year period.

The high-dose influenza vaccine is designed specifically for older adults because their immune systems often become less effective at fighting infection as they age. This version of the vaccine contains four times the antigen—the component that generates an immune response—than standard-dose vaccines.

Due to these factors, the U.S. Centers for Disease Control and Prevention (CDC) recommends that all adults aged 65 and older receive the high-dose vaccine.

Immune Response and Inflammation

Medical researchers are exploring the link between vaccination and a reduced risk of neurodegeneration. A leading hypothesis suggests that inoculation may strengthen immune defenses while simultaneously dampening inflammation, which is believed to play a role in the development of Alzheimer’s disease.

The study also noted differences in how the vaccine affected different genders. While both men and women experienced a lower risk of Alzheimer’s after receiving the high-dose vaccine compared to the standard dose, the effect appeared to be more consistent and lasted longer in women.

Public Health Context and Awareness

Alzheimer’s is the most common form of dementia. As of 2025, the disease affected more than 7 million seniors, and that number is expected to more than double by 2050.

Despite the CDC recommendations, some medical professionals may not be fully aware of the availability of the high-dose option. Dr. Paul Schulz, a professor of neurology at the University of Texas Health Science Center at Houston and a senior researcher on the study, expressed surprise regarding this gap in knowledge.

I was stunned that, as a physician, I didn’t know a higher dose was offered

Dr. Paul Schulz

The findings contribute to a growing body of evidence linking vaccination and immune system activity to a reduced risk of dementia in the elderly population.