MONDAY, April 6, 2026 (HealthDay News) -- For adults aged 65 years and older, the risk for incident Alzheimer dementia (AD) is lower for those who receive a high- versus standard-dose of inactivated influenza vaccine (IIV), according to a study published online April 1 in Neurology.
Avram Samuel Bukhbinder, M.D., from The McGovern Medical School at UTHealth in Houston, and colleagues conducted a retrospective cohort study using data from 2014 to 2019 from the IQVIA PharMetrics Plus for Academics to examine the risk for AD among adults 65 years and older after high-dose IIV (H-IIV) versus standard-dose IIV (S-IIV). Participants were 65 years and older with at least two years of continuous medical and pharmaceutical coverage and no previous diagnostic or pharmacotherapeutic indicators of cognitive impairment: 120,775 unique participants were included in the H-IIV group and 44,022 unique participants were included in the S-IIV group.
The researchers observed an association for H-IIV with significantly lower AD risk during month 1 to 25 postvaccination (minimum number needed to treat, 185.2 at 25 months). The risk reduction persisted longer in women than men after sex stratification.
"Understanding the mechanisms through which influenza vaccines and immunogenic enhancements influence AD pathology and presentation could inform the targeted interventions and public health strategies to mitigate the growing population burden of AD," the authors write.
One author disclosed ties to the pharmaceutical industry.