Low cognitive ability in early adulthood is associated with reduced lung function in middle age: The Vietnam experience study

Abstract

Objective: Reduced lung function has been linked to poorer cognitive ability later in life. In the present study, the authors examined the converse: whether there was a prospective association between cognitive ability in early adulthood and lung function in middle age. Methods: Participants were 4256 male Vietnam-era US veterans. Cognitive ability was assessed by the Army General Technical Test on enlistment when participants were, on average, 20 years old (range: 17-34). Data on ethnicity and place of service were extracted from army files. Smoking behaviour, alcohol consumption, basic socio-demographics and whether participants had a physician-diagnosed chronic disease were determined by telephonic interview in middle age in 1985. Forced expiratory volume in one second (FEV1) was measured by spirometry at a 3-day medical examination in 1986. Height and weight were also measured. Results: In linear regression models, poor cognitive ability in early adulthood was associated with reduced lung function in middle age, first adjusting for age and height, β=0.17, p<0.001, then additionally adjusting for circumstantial, socio-demographic, lifestyle and health factors, β=0.12, p<0.001. The same results were obtained when the analysis was confined to nonsmokers. Conclusion: Not only is lung function related to subsequent cognitive ability, but poor cognitive ability earlier in life is also associated with reduced lung function in middle age.