From breath to brain: influenza vaccination as a pragmatic strategy for dementia prevention.

Abstract

Aging populations require scalable strategies to delay or prevent dementia. Beyond the prevention of neurological injury associated with seasonal influenza, vaccination may help mitigate vascular and neuroinflammatory injury underlying cognitive impairment. Influenza infection can cause a marked short‑term increase in myocardial infarction risk, and acute infections have also been associated with transient increases in stroke risk. Experimental models show prolonged microglial activation and synaptic loss even from non-neurotropic strains - processes likely modulated by vaccination. Epidemiologic data consistently support this evidence; a 2023 meta-analysis, including observational studies, of ~ 2.09 million adults identified a 31% lower risk of incident dementia; US matched cohorts demonstrated 40% lower risk of Alzheimer's disease (absolute decrease 3.4%); Veterans Health data showed a 0.86 hazard ratio for dementia; and UK Biobank data showed lower risk for all-cause (0.83 h), and vascular dementia (0.58 h) with a dose-response association by vaccination term. Randomized trials suggest fewer adverse cardiovascular events in vaccine recipients giving even more biological plausibility to this concept. Despite that, prevention through influenza vaccination is not fully realized in older adults due to low levels of perceived risk, vaccine confidence, and variations in clinical practice guidance. This public health perspective reviews the physiopathological and epidemiological evidence in support of influenza vaccination as a pragmatic, dementia risk-modifying intervention within healthy aging strategies and encourages the inclusion of vaccination status in hospital discharge and chronic-care pathways, integration of cognitive outcomes in monitoring, and equity-centered research to eliminate barriers to behavioral and implementation.