Researchers at the University of Texas Health Center in Houston found that people who received at least one flu vaccine were 40 percent less likely to develop Alzheimer’s disease within four years than their unvaccinated peers. This is reported in an article published in the Journal of Alzheimer’s Disease.
The researchers compared the risk of developing Alzheimer’s disease among patients with and without prior influenza vaccination by analyzing a nationwide sample of 935,887 influenza vaccinated patients and 935,887 unvaccinated patients.
During a four-year follow-up, approximately 5.1 percent of vaccinated patients developed Alzheimer’s disease. Among the unvaccinated, the incidence was 8.5 percent. The vaccines had a protective effect, with its strength increasing with the number of years a person received the annual influenza vaccine. The risk of developing a neurodegenerative disease was lowest among those who were vaccinated each year.
According to the authors of the paper, the mechanisms underlying this relationship require further study. The effect is not expected to be specific to influenza vaccines. Previous studies have shown a reduction in the risk of dementia associated with various vaccinations in adulthood, including tetanus, polio and herpes. It is likely that some vaccine-preventable diseases contribute to an increased risk of dementia.