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Pollution Accelerates Cognitive Decline And Raises Stroke Risk

16 Feb 2012

In the February 13 issue of the Archives of Internal Medicine, one of the JAMA/Archives journals, two studies examine the association between air quality and the risk of ischemic stroke and cognitive decline in older women.

In the first study, Gregory A. Wellenius, Sc.D., of Brown University, Providence, R.I., and his team assessed the link between the risk of ischemic stroke among individuals admitted between 1999 and 2008 to Beth Israel Deaconess Medical Center who were living in the greater Boston area, and the alterations in fine particulate matter (PM) air pollution (PM<2.5 μm in diameter [PM2.5]) levels. In the Boston area during the study period, PM<2.5 levels did not exceed current EPA standards. The team examined 1,705 medical records of individuals hospitalized with ischemic stroke.

According to the researchers, increased risk of acute cardiovascular events have been linked to daily alterations in levels of ambient fine particular matter air pollution [PM<2.5].

The researchers explain:

“We found that ischemic stroke risk was 34 percent higher on days with moderate PM<2.5 levels compared with days with good levels, according to the EPA’s Air Quality Index. Stroke risk was more strongly associated with concentrations of black carbon and NO2 (nitrogen dioxide) markers of traffic pollution than with components linked to non-traffic sources.”

Robert D. Brook, M.D., of the University of Michigan, Ann Arbor, and Sanjay Rajagopalan, M.D., of the Ohio State University Medical Center, Columbus, write in an invited commentary:

“Why are these findings important? Current U.S. and World Health Organization air quality standards focus on daily and annual PM<2.5 mean concentrations. There is no biological basis that these specific durations of exposure are required to instigate strokes or other CV (cardiovascular) events.”

In the second study, Jennifer Weuve, M.P.H., Sc.D, of Rush University Medical Center, Chicago, and her team used data from the Nurses’ Health Study Cognitive Cohort, which included 19,409 women aged between 70 to 81 years in the U.S., in order to assess both coarse and fine air pollution in relation to cognitive decline in older women.

The researchers highlight that extremely little is known regarding the role of particulate matter exposure and cognitive decline.

They explain:

“In this large, prospective study of older women, higher levels of long-term exposure to both PM2.5-10 and PM2.5 were associated with significantly faster cognitive decline.”

According to the researchers, these associations were present at levels of PM exposure common in several regions of the U.S.:

“Therefore, 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.”

Rajiv Bhatia, M.D., M.P.H., of the San Francisco Department of Public Health, explained:

“The strong and growing evidence of the harms of PM2.5 demands scrutiny of societal efforts to reduce exposure.”

Written by Grace Rattue
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

Archives of Internal Medicine


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