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The tiny particles in vehicle exhaust and other sources of air pollution may hasten cognitive decline in older adults, according to a new US study.
“We decided to examine the link between air pollution and cognitive function in older adults because there is growing evidence that fine particulate matter air pollution affects brain health and development, but relatively little attention has been given to what this means for the aging brain,” said Jennifer Ailshire, who co-wrote the report.
Ailshire is with the Center for Biodemography and Population Health and the Andrus Gerontology Center at the University of Southern California in Los Angeles.
She, along with Philippa Clarke of the Institute for Social Research at the University of Michigan, Ann Arbor, say that based on their results, improvements in air quality may be an important strategy for reducing age-related cognitive decline.
There has been some evidence that people living in more polluted areas have greater rates of cognitive decline, and the link is not explained by wealth or other social factors, the researchers point out in The Journals of Gerontology: Series B.
They gathered information from one wave of a large ongoing survey started in 1986, and focused their analysis on 780 participants who were 55 years of age or older at the time of the 2001/2002 survey.
Routine measurement of air pollution by census tract did not start until the late 1990s, they explain.
Cognitive function was measured by math and memory tests and participants got a score based on the number of cognitive errors they made.
Air pollution levels for each participant’s neighborhood were calculated using fine particulate levels reported by the U.S. EPA’s Air Quality System. Those pollution particles 2.5 microns or smaller (PM2.5) can travel deep into the lungs and enter the bloodstream, past research has shown.
Ailshire and Clarke found the average PM2.5 concentrations in the study participants’ environments were 13.8 micrograms per cubic meter, which is above the EPA’s air quality standard of 12 micrograms per cubic meter.
Then they compared the cognitive error scores to pollution levels and found that people living in high pollution areas, with 15 micrograms per cubic meter or more of PM2.5 had error scores one and a half times those of the participants who lived in low pollution areas with no more than 5 micrograms per cubic meter.
Poverty and other social factors as well as health problems can influence cognitive function, the authors note. And poorer neighborhoods tend to