Long-term exposure to particulate matter (PM) (coarse PM: 2.5 to 10 µm in diameter [PM2.5-10] and fine PM: <2.5 µm in diameter [PM2.5]) is associated with faster cognitive decline in older women, according to a study published in the Feb. 13 issue of the Archives of Internal Medicine.
Jennifer Weuve, M.P.H., Sc.D., from the Rush University Medical Center in Chicago, and colleagues investigated long-term exposure to air pollution with PM2.5-10 and PM2.5 in relation to cognitive decline in a cohort of 19,409 U.S. women aged 70 to 81 years. Exposure to PM was estimated using geographic information system-based spatiotemporal smoothing models, prior to baseline cognitive testing. Cognition was evaluated via validated telephone assessments, administered three times, at approximately two-year intervals.
The investigators found that elevated levels of long-term exposure to PM2.5-10 and PM2.5 correlated with significantly faster cognitive decline. On a global score, two-year decline was 0.020 and 0.018 standard units worse for each 10 µg/m³ increase in exposure to PM2.5-10 and PM2.5, respectively. These differences in the cognitive trajectory were similar to those between women about two years apart in age in the cohort.
"Higher levels of exposure to ambient PM are associated with worse cognitive decline. Importantly, these associations were present at levels of PM exposure typical in many areas of the United States," the authors write. "If our findings are confirmed in other research, air pollution reduction is a potential means for reducing the future population burden of age-related cognitive decline, and eventually, dementia."