Association of midlife air pollution and road proximity exposure with 29-year cognitive decline

Midlife ambient air pollution exposures may be etiologically relevant to late-life cognition. We considered whether midlife air pollution and traffic exposures are associated with midlife to late-life cognitive change. Our sample included Atherosclerosis Risk in Communities (ARIC) cohort study participants with cognitive testing at Visit 2 (1990-1992, ages 48-67), which was repeated at Visit 4 (1996-1998), Visit 5 (2011-2013), Visit 6 (2016-2017), and Visit 7 (2018-2019). At participant addresses, we estimated: [i] 1990-1992 average ambient air pollutant concentrations for 18 pollutants using Community Multiscale Air Quality chemical transport model output fused with observed annual concentrations, and [ii] distance to major roads and road density within a 500-meter radius. We used meta-analysis of site-specific adjusted linear mixed-effects models to quantify associations between each exposure and 29-year cognitive change. Among 12,700 eligible participants, mean age was 57 years, 56 % were female, 24 % identified as Black, and 79 % had at least a high school education. There was no statistical support linking higher exposures to criteria air pollutants, most PM components, or roadway proximity in midlife and cognitive change. However, there was some suggestion that higher midlife exposures to nitrates, copper, iron, lead, and zinc may be associated with greater 29-year decline in executive function and that higher midlife exposures to copper and lead may be associated with greater declines in a global z-score. Our cohort study does not support a link between midlife exposures to most air pollutants and mid- to late-life-cognitive change. Confirmation or repudiation of suggestive findings in an independent dataset is warranted.