Older adults who receive a higher dose of the influenza vaccine have a significantly lower risk of developing Alzheimer's disease than those who get the standard dose, according to new research led by UTHealth Houston. The work extends a line of investigation the group has been pursuing for several years into the relationship between routine vaccination and dementia risk.
The team's 2022 study, led by Paul Schulz, MD, professor of neurology at McGovern Medical School at UTHealth Houston and director of the Neurocognitive Disorders Center at UTHealth Houston Neurosciences, found that people 65 and older who received a flu vaccine had a reduced risk of Alzheimer's compared with those who did not. The new finding sharpens that picture by suggesting the size of the dose, not just the fact of vaccination, tracks with the degree of risk reduction.
That distinction matters because it points toward a possible mechanism worth testing rather than a simple correlation between vaccination and generally healthier behavior. If a stronger immune response is doing the work, it gives researchers a specific hypothesis to pursue in future studies of how the immune system interacts with the aging brain.
The stakes are considerable. Alzheimer's disease, the most common form of dementia, affects more than 7 million Americans aged 65 and older as of 2025, roughly 1 in 9 people in that age group, and that number is projected to more than double by 2050. Even a modest shift in risk across a population that large would register.