High-Dose Flu Vaccine Associated with Lower Risk of Alzheimer's in Older Adults

A large observational study published in Neurology found that “receiving a high-dose flu vaccine is associated with a significantly lower risk of Alzheimer’s disease than a standard-dose vaccine in adults aged 65 and older.” CIDRAP has the news.

Researchers analyzed health data from about 165,000 older adults who received either a high-dose or standard-dose influenza vaccine. The high-dose flu vaccine “reduced the risk of Alzheimer’s in those 65 and older by nearly 55% over a roughly two-year period.” The standard-dose vaccine was also tied to a 40% reduced risk of the same. The CDC recommends “all adults 65 years and older receive the high-dose vaccine.”

One hypothesis about the link between vaccination and reduced risk of neurodegeneration is that “inoculation strengthens immune defenses while dampening inflammation. Inflammation is thought to play a role in the development of Alzheimer’s disease.” The shingles vaccine has also been linked to slowed neurodegeneration.

The study’s large sample size is a key strength, and comparing groups of vaccinated adults is a new step forward in the research. However, there is a risk of “healthy-user bias, or the possibility that people who receive high-dose vaccines may seek healthcare in ways that also affect dementia risk.” The results regardless align with the existing body of research.