Air Pollution May Hurt Cognition, Increase Strokes

By: HEIDI SPLETE, Cardiology News Digital Network – 02/13/12. The increased stroke risk was highest within 12-14 hours of exposure to PM2.5 and was most strongly associated with traffic-related pollution, the researchers noted.

The mean age of the patients was 73 years; 55% were white, and 68% were women. The most common determined causes of the strokes were small-vessel strokes (26%), cardioembolism (25%), and large-artery atherosclerosis (20%).

When the patients were examined by clinical subgroups, increased pollution levels were associated with stroke in patients with large-artery atherosclerosis (odds ratio 1.24) and small-vessel strokes (1.19), but not in patients with strokes due to cardioembolism. There was no evidence that comorbid diabetes, hypertension, atrial fibrillation, or a history of stroke increased susceptibility to pollution-related strokes, the researchers noted.

Although the observed relative risk of stroke was modest, the findings suggest that “if the association between stroke and pollution is causal and a linear dose-response occurs, a 2-microgram/m3 reduction in mean PM2.5 levels (approximately 20%) during this time period might have averted approximately 6,100 of the 184,000 stroke hospitalizations observed in the U.S. Northeast region in 2007 alone,” the researchers said.

If pollution levels decline, further data on stroke timing and patient demographics can be used to show whether pollution control impacts stroke risk, they added.

In a related finding, Jennifer Weuve, Sc.D., of Rush University Medical Center, Chicago, and colleagues found that long-term exposure to both coarse and fine PM was significantly associated with faster cognitive decline in older adults. They reviewed data from 19,409 women aged 70-81 years in the Nurses’ Health Study Cognitive Cohort and used geographic information to estimate short-term exposure (1 month) and long-term exposure (7-14 years) before the women underwent baseline cognitive testing. Read Full Article