A lifecourse approach to the relationship between lung function and cognition function in late life: findings from the Mysore studies of Natal effect on Ageing and Health (MYNAH) in South India

Abstract

Background: Emerging evidence from high income settings indicates that lung function may be an independent determinant of cognitive abilities in late life. Despite a high burden of chronic lung disorders and neurocognitive disorders, there are limited data exploring the relationship between lung and cognitive function in later life in low- and middle-income (LMIC) settings. Methods: Between 2013 and 2016, 721 men and women from the Mysore Birth Records Cohort in South India, aged 55-80 years, were retraced and underwent standardised assessments for sociodemographic characteristics, cardiometabolic risk factors, lung function, cognitive function and mental health. Approximately 20 years earlier, a subset of them had assessments for cardiometabolic risk factors (n=522) and lung function (n=143). Results: Forced Expiratory Volume at one second (FEV1) and six seconds (FEV6) were higher among men than women. Women had higher immediate and delayed recall scores compared to men. Multivariate models indicated that those with lower FEV1 (lts) and FEV1/FEV6 ratio in late life had lower composite cognitive score (SD, standard deviation), independent of growth and environment in early life and childhood, attained education, socioeconomic position, cardiometabolic disorders in mid-and late life and lifestyle factors (0.29 SD per litre 95% confidence interval [CI] (0.10, 0.50) p=0.006 for FEV1 and 1.32 SD (0.20, 2.50) p=0.02 for FEV1/FEV6 ratio). Lung function in midlife was unrelated to cognitive outcomes in late life. Conclusions: Causality cannot be inferred from cross sectional associations. Therefore, causality is best explored in longitudinal studies with serial, but contemporaneous measurements of both lung and cognitive function. Mechanistic studies that examine the role of shared risk factors like environmental pollutants and biomass exposure on this relationship are urgently required in LMICs.