By Kathleen Doheny
WebMD Health News
Reviewed by Louise Chang, MD
Nov. 16, 2012 -- Air pollution may be bad for older brains, a new study shows.
Older adults who live in areas of high pollution did not do as well on tests of memory and other thinking skills, according to a new study.
"We know that air pollution is harmful for a child's developing brain," says researcher Jennifer Ailshire, PhD. She is a National Institute on Aging postdoctoral fellow at the Andrus Gerontology Center of the University of Southern California.
"Now we are starting to understand that air pollution is also harmful for the aging brain," she says.
She presented the findings today at the Gerontological Society of America meeting in San Diego.
Air Pollution and Health
Air pollution has long been linked to a higher risk of heart and breathing problems in older adults. It has also been linked to breathing problems in children.
Her new study, Ailshire says, is one of the first to examine the effects of air pollution on the memory and other thinking skills of older men and women who reflect the general population.
She evaluated nearly 15,000 men and women, age 50 and older. They took part in the 2004 Health and Retirement Study. They were interviewed and tested by phone.
''They are asked to do memory tests -- given a list of words and asked to repeat them," Ailshire says. "They are asked to name the date, the president, and do some counting tests." Language is also tested.
The test scores range from 1 to 35.
Ailshire then looked at the 2004 annual average level of fine air particulate matter from the Environmental Protection Agency's monitoring systems around the country.
She found that exposures to these small particulates ranged from low to high. Some were at or above the level that the Environmental Protection Agency says could be linked with health problems.
When Ailshire compared exposures and test scores, she found that every 10-point increase in air pollution exposure was linked with a one-third point drop in the score.
That may seem small, but she says it is the equivalent of aging three years.
Those who live in busy urban areas, such as Los Angeles, Pittsburgh, Birmingham, Ala., and Atlanta, are more likely to be exposed to this type of pollution, she says. It's produced by road dust, among other sources. Levels are higher in sprawling urban areas with heavy traffic.
Long-Term Exposure to Air Pollution
The findings echo those of Jennifer Weuve, ScD, MPH. She is an assistant professor at the Institute for Healthy Aging at Rush University Medical Center, Chicago.
She reviewed the findings.
In her own study, published earlier this year in the Archives of Internal Medicine, she evaluated nearly 20,000 women who were enrolled in the Nurses' Health Study Cognitive Cohort.
Long-term exposure to air pollution, she also found, was linked with worse declines in thinking skills.
The new study, Weuve says, is more representative of the general population than hers. It includes men as well as women.
Reducing Exposure to Air Pollution
The smaller particles of pollutants can be inhaled deep into the lungs, some research suggests.
"Some experts have found the particles can actually get into the brain," Weuve says.
"We know that air pollution produces sort of a cascade of inflammatory responses in people," Ailshire says. "In general, inflammation is not good." It's linked to heart disease and other problems.
To reduce exposure, do not exercise outdoors on high pollution days, Weuve says.
"When commuting, drive with the air recirculating button on," she says. "If you have central air or forced air heating, you can install HEPA filtration. That can help keep the air in your home cleaner."
These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.
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