Peak Expiratory Flow Predicts Incident Dementia in a Representative Sample of U.S. Older Adults: The National Health and Aging Trends Study (NHATS).

Abstract

Dementia is an increasingly important public health problem with various risk factors. Respiratory function, measured via peak expiratory flow (PEF), may be a modifiable dementia risk factor. We investigated the association between PEF and incident dementia in 5 935 older adults from the National Health and Aging Trends Study (NHATS) from 2011 to 2014. Baseline PEF, expressed as a standardized residual (SR) percentile, was analyzed as a predictor of incident dementia using discrete-time proportional hazards models, while controlling for several health and sociodemographic covariates. After 14 332 person-years of follow-up, 9.0% (N = 536) had incident cases of dementia. Compared to the lowest PEF category (SR-percentile < 10%), the highest PEF category (SR-percentile ≥ 80%) had 49% lower risk of incident dementia (hazard ratio [HR] = 0.51; 95% confidence interval [CI; 0.37, 0.71]), and the second highest PEF category (SR-percentile 50%-80%) had 25% lower risk of incident dementia (HR = 0.75; 95% CI [0.56, 1.00]). A sensitivity analysis using multiple imputation to account for missing PEF measurements yielded similar associations with incident dementia. These associations suggest a dose-dependent relationship such that higher PEF categories were more protective against incident dementia. PEF may be considered as an easily administered, low-cost measure of respiratory function and a potentially modifiable dementia risk factor. Improving PEF may reduce dementia risk through vascular mechanisms, such as increased brain oxygenation. Future research should explore potential causal pathways between PEF and dementia.