Fine particulate matter is associated with lower executive functioning in middle-aged and older adults: Cardiometabolic disease as a mediator

Background PM2.5 pollution is expected to worsen in many places due to climate change, as a result of hotter temperatures, less precipitation, and increases in wind speed. PM2.5 exposure has adverse effects on humans that may accelerate the aging process, such as worsening cognitive functioning and cardiometabolic disease. Less is known about whether physical and mental health conditions mediate the relationship between PM2.5 exposure and aging-related cognitive and functional limitations. Methods Longitudinal data from the Midlife in the United States study (MIDUS 2: 2004-05; MIDUS 3: 2013-14) were used, with a sample of approximately 5000 individuals aged 32 to 84. Based on individuals’ residential addresses at each wave, we identified census tract-level PM2.5 exposure as defined by five-year annual averages. Missing data were handled using multiple imputation by chained equations. We examined cross-sectional and longitudinal associations between PM2.5 exposure and aging-related limitations (i.e., executive functioning and functional limitations), and tested cardiometabolic disease and depressive symptoms as mediators. Results Higher PM2.5 exposure was associated with lower executive functioning cross-sectionally and longitudinally, but not with functional limitations. The cross-sectional association between PM2.5 and executive functioning was partially mediated by cardiometabolic disease, accounting for 8.1% of the estimate. Depressive symptoms were not a significant mediator. Conclusions Findings suggest the importance of considering the indirect ways in which climate change may impact health of middle-aged and older adults.