Long-Term Exposure to Multiple Environmental Factors and Late-Life Cognitive Decline

Individual environmental exposures have been linked to later-life cognition, but their combined effects, particularly on cognitive decline, remain unclear. Using data from 18,462 participants in the Nurses' Health Study cognitive substudy, we assessed the independent and joint associations of long-term exposure to multiple environmental factors with cognitive function and decline, using generalized estimating equations (GEE) and quantile g-computation models, allowing exposures to operate in both protective and harmful directions. Cumulative average exposures to air pollution, seasonal temperature, noise, greenness, light at night (LAN), and neighborhood socioeconomic status (nSES) from 1988 onward were assigned to updated residential addresses. In multiexposure GEE models, each interquartile-range increase in greenness and nSES was associated with 0.026 (95% CI: 0.013, 0.040) and 0.017 (0.005, 0.029) standard-unit increases in cognitive function, respectively. Higher summer temperature was associated with a 0.011 (-0.023, 0.000) standard-unit decrease. Jointly, each quartile increase across all exposures corresponded to a 0.013 (0.001, 0.024) standard-unit higher cognitive score. Higher summer maximum temperature and LAN were associated with faster cognitive decline only in single-exposure models, while no significant joint association with decline was observed. These findings suggest that enhancing protective exposures (greenness, nSES) may help offset the adverse effects of harmful exposures (high temperature, LAN) and support healthier cognitive aging.