Longitudinal Changes in Peak Expiratory Flow Predict Risk for Incident Dementia

Background Impaired respiratory function, measured via peak expiratory flow (PEF), has been associated with increased dementia risk. However, much of the current literature uses cross-sectional measures of PEF, whereas longitudinal relationships between changes in respiratory function and dementia risk are underexplored. Methods Using 10 years of data (2011-2021) from 2,439 adults ages 65 and older in the National Health and Aging Trends Study (NHATS), we examined whether 5-year changes in PEF (2011-2016) were associated with risk for incident dementia over the subsequent 5-year period (2017-2021). PEF slopes for each participant were estimated using linear mixed-effects models and then grouped into quartiles: rapid, moderate, mild, and no declines. Discrete-time Cox proportional hazards models were used to estimate the risk for incident dementia by PEF slope category, while controlling for several health and sociodemographic characteristics. Results After excluding dementia cases during the exposure window (2011-2016), we identified 338 cases of incident dementia (13.9%) between 2017-2021. Rapid PEF declines between 2011-2016 were associated with 85% higher risk for incident dementia between 2017-2021 compared to those with no declines in PEF (HR=1.85; 95% CI [1.24, 2.76]). Results were robust to several sensitivity analyses. Conclusions These findings demonstrate that declines in PEF may precede declines in cognition, suggesting that respiratory function may be an important dementia risk factor in older adults. Additionally, these findings highlight the utility of measuring PEF via a peak flow meter, which is a simple and inexpensive measure of respiratory function.