Long-term Exposure to Outdoor Air Pollution and Cognitive Performance: Findings from the Harmonised Cognitive Assessment Protocol Sub-Study of the English Longitudinal Study of Ageing (ELSA-HCAP)

Giorgio Di Gessa, University College London
Mikaela Bloomberg, University College London
Jinkook Lee, University of Southern California
Sara Adar, University of Michigan
Paola Zaninotto, University College London

Although air pollution is linked to worse cognitive performance, specific cognitive domains and air pollution sources remain understudied. This study examined associations between 8-10 years of exposure to NO2, total PM2.5, and source-specific PM2.5 and cognitive scores (total, memory, executive function, language) in older adults. We used data from the 2018 Harmonized Cognitive Assessment Protocol (HCAP) sub-study of the English Longitudinal Study of Ageing (N=1,127). Pollutant concentrations (2008/10-2017) were summarised using means and group-based trajectory modelling. Linear regression models were used to assess the relationships of long-term air pollution exposure with memory, executive function, language, and global cognitive function after adjustment for key individual and neighbourhood-level confounders. Findings suggest that associations between outdoor air pollution trajectories and cognition are mostly inverted j-shaped, suggesting that respondents exposed to the highest residential levels of NO2 and total PM2.5 had worse performance for global cognition [ß=-0.241; 95%CI=(-0.46,-0.02) and ß=-0.334; 95%CI=(-0.55,-0.12) respectively] than those exposed to average levels of pollution. Similar associations were also found for executive function, memory, and language. Higher emissions from industry and residential combustion as well as biofuel, coal, oil and natural gas combustion were associated with worse language scores. Reducing air pollution, particularly in high-exposure areas, may benefit older adults' cognitive health.

Keywords: Longitudinal studies , Health and Morbidity, Population, Environment, and Climate Change

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