Traffic-related air pollution, adherence to healthy lifestyles, and risk of cognitive impairment: A nationwide population-based study

Background: Traffic-related air pollution (TRAP) is a risk factor for cognitive function, whereas healthy lifestyles are associated with better cognition. We aimed to examine their joint effects on cognition among the Chinese elderly.Methods: The data from the Chinese Longitudinal Healthy Longevity Survey was used. Participants' cognitive performance was assessed by the Chinese version of the mini-mental state examination. Residential proximity to major roadways was obtained through self-report and categorized into five categories: > 300 m, 201-300 m, 101-200 m, 50-100 m, and < 50 m, serving as a surrogate for TRAP. Six lifestyle behaviors (smoking, drinking, exercise, body mass index, sleep duration, and dietary diversity) were taken into account to calculate healthy lifestyle scores. The scores ranged from zero to six and were then divided into three groups: healthy (5-6), intermediate (2-4), and unhealthy (0-1). Logistic regression models were applied to investigate the joint effects of TRAP and healthy lifestyle scores on cognition.Results: Compared to participants living < 50 m from major roadways and adopting an unhealthy lifestyle, those living > 300 m from major roadways and adopting a healthy lifestyle had a significantly decreased risk of cognitive impairment. Stratified analysis indicated that the associations between TRAP and cognitive impairment were more pronounced among participants adopting an unhealthy lifestyle compared to the participants adopting a healthy lifestyle. Conclusions: TRAP may impair cognitive function, and its detrimental impacts may be lessened by healthy lifestyles.