Air pollution and impulsive choice in aging: evidence from delay discounting

Heightened air pollution exposure is associated with an increased risk for developing neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease, yet it is unclear how pollution impacts the aging brain more broadly. Rodent research has shown that higher air pollution exposure is associated with increased impulsive behavior, operationalized as a preference for immediate reward in delay discounting tasks. We examined this relationship in middle-aged and older humans by analyzing associations between residential pollution exposure and time-based reward preferences. One hundred three (103) adults aged 40-80 completed a delay discounting task. We estimated long-term residential exposure to fine particulate matter (PM_2.5), a prominent air pollutant, using participant address information and satellite pollution data. We found that higher residential PM_2.5 exposure was significantly associated with a higher preference for more immediate rewards, even after controlling for demographic factors including income and education. A preference for immediate rewards has been independently associated with a higher risk of addictive behaviors, including substance abuse and gambling disorders, indicating that PM_2.5 exposure may increase the emergence of these conditions. We discuss these results in detail along with potential underlying biological mechanisms, implications on human behavior, and future research directions.