A new study shows the seasonal flu shot can lower the risk of Alzheimer’s disease in millions of Amerians.Researchers at the Alzheimer’s Association International Conference reported today that at least one flu shot was linked to a 17% reduction in Alzheimer’s. More frequent vaccinations were associated with another 13% reduction. Researchers also found the protective association between the vaccine and the risk of Alzheimer’s was strongest for those who received their first vaccine at a younger age. For example, those who go their first documented flu shot at age 60 benefited more than those who first received it at 70.While the study doesn’t explain why flu vaccinations are linked to a reduced risk of Alzheimer’s disease, some experts speculate the vaccine may impact brain inflammation that could lead to the disease, said Dr. Steven DeKosky, professor of neurology at the University of Florida and deputy director of UF’s McKnight Brain Institute.“The vaccine activates the immune system to defeat the flu virus itself,” he said. “The activation may have beneficial effects that fight off or slow down the inflammation associated with AD.” However, the Mayo Clinic says most scientists believe Alzheimer’s disease is caused by a combination of genetic, lifestyle and environmental factors that affect the brain over time.