Researchers at UTHealth Houston found that older adults receiving a high-dose influenza vaccine showed a significantly lower risk of developing Alzheimer's disease compared to those given standard-dose shots. The study, published in Neurology, analyzed data from nearly 200,000 men and women ages 65 and older. Standard-dose flu vaccination was associated with a 40% reduction in Alzheimer's risk, while high-dose vaccination was linked to a nearly 55% reduction.
The discovery emerged from a conversation between Paul Schulz, MD, a professor of neurology at McGovern Medical School at UTHealth Houston, and local public health officials who asked whether different vaccine doses might affect Alzheimer's risk. Schulz led an earlier 2022 study showing flu vaccination was associated with reduced Alzheimer's risk in older adults.
The high-dose vaccines contain four times as much influenza antigen as standard doses. The Centers for Disease Control and Prevention recommends high-dose formulations as a preferred option for adults 65 and older because their immune systems respond less effectively to conventional vaccines.
The reduction in Alzheimer's risk appeared particularly pronounced among women. However, the study demonstrates an association rather than cause and effect. Schulz stated, "So we started looking, and sure enough, we were able to put together thousands and thousands of people over the age of 65 who got the high- or low-dose vaccine."
Additional research is needed to determine whether high-dose flu vaccination directly reduces Alzheimer's risk and to understand the biological mechanisms that might explain the connection.