Pulmonary function and trajectories of cognitive decline in aging population

Abstract

Background: The number of older people with cognitive impairment is increasing worldwide. Impaired lung function might be associated with cognitive decline in older age; however, results from large longitudinal studies are lacking. In this study, we examined the longitudinal associations between pulmonary function and the trajectories of cognitive decline using prospective population-based SHARE data from 14 countries. Methods: The analytic sample included N = 32,049 older adults (Mean age at baseline = 64.76 years). The dependent variable was cognitive performance, measured repeatedly across six waves in three domains: verbal fluency, memory, and numeracy. The main predictor of interest was peak expiratory flow (PEF). The data were analyzed in a multilevel accelerated longitudinal design, with models adjusted for a variety of covariates. Results: A lower PEF score was associated with lower cognitive performance for each domain as well as a lower global cognitive score. These associations remained statistically significant after adjusting for all covariates Q4 vs Q1 verbal fluency: unstandardized coefficient B = -3.15; numeracy: B = -0.52; memory: B = -0.64; global cognitive score B = −2.65, all p < .001). However, the PEF score was not found to be associated with the rate of decline for either of the cognitive outcomes. Conclusions: In this large multi-national longitudinal study, the PEF score was independently associated with lower levels of cognitive functions, but it did not predict a future decline. The results suggest that pre-existing differences in lung functions are responsible for variability in cognitive functions and that these differences remained stable across aging.

Keywords

• Pulmonary function
• Peak expiratory flow
• Cognitive decline
• Cross-cultural
• Longitudinal