Exposure to ambient PM2.5 and cognitive function in older adults in Mexico

Abstract

Background: Recent observational studies have shown that chronic exposure to fine particulate matter (PM2.5) is associated with a poorer cognitive function in older adults. However, evidence of the association with cognitive test performance has not always been consistent. Furthermore, most of the available studies are cross-sectional and have been carried out in developed countries. Objective: To evaluate the association between exposure to ambient PM2.5 and cognitive function in adults participating in the Mexican Health and Aging Study (MHAS), in 2012 and 2015. Methods: Measures of cognitive function, sociodemographic and health data were obtained for each MHAS participant in 2012 and 2015 waves. A total of 1544 for 2012 and 693 for 2015 adults aged 50 years and older, who had exposure and cognitive test data, composed the preliminary analytical samples. Cognitive function was assessed using a modified version of the screening portion of the Cross-Cultural Cognitive Examination (CCCE), including tests of orientation, verbal learning memory, verbal recall memory, visual scanning, visuospatial abilities, visual memory, verbal fluency, and numeracy. Long term exposures to PM2.5 were estimated by a spatial analysis using concentrations from monitors and the Inverse Distance Weighting (IDW) method, 1, 2 and 5 years preceding cognitive testing of each participant. Association between exposure to PM2.5 and cognitive function was estimated using linear regression models. Preliminary Results: Adjusted linear regression models for 2012, showed statistically significant lower scores in 2nd and 3rd PM2.5 exposure tertiles, compared with lower exposure tertiles, for verbal learning memory (-0.175 to -0.184), visual scanning (-2.26 to -2.64) and visual memory (-0.23 to -0.39) tests. Conclusions: Environmental exposure to PM2.5 seems to affect neurocognitive functioning in Mexican adults 50 years and older, a complementary analysis will be performed and presented.