Air Pollution Tied to Stroke, Cognitive Slide

I do wonder how much is correlation vs. cause, you could also say stroke is tied to breathing.
And debunked here: Although they don't say why it is bad
More bad statistics presented as science by a gullible media.
http://junkscience.com/2012/02/14/warning-over-air-pollution-link-to-stroke-research/

http://www.medpagetoday.com/Cardiology/Strokes/31158?utm_source=cardiodaily&utm_medium=email&utm_content=aha&utm_campaign=02-13-12&eun=gd3r&userid=424561&email=oc1dean@yahoo.com&mu_id=

Airborne pollution can have serious consequences for the brain and the heart even at typical levels of exposure, according to the results of two studies published in the Feb. 13 issue of Archives of Internal Medicine.

In one analysis, researchers led by Gregory Wellenius, ScD, of Brown University in Providence, R.I., found that short-term exposure to fine particulate matter – even at levels allowed by the EPA – can increase the risk of ischemic stroke.

In the other study, a team led by Jennifer Weuve, ScD, of Rush University Medical Center in Chicago, and colleagues found that long-term exposure to particulate matter speeded up cognitive decline in older women.

The first report "adds to the already strong evidence linking (particulate matter) to cardiovascular effects," wrote Rajiv Bhatia, MD, of the San Francisco Department of Public Health, in an accompanying commentary.

And, he added, the cognition study suggests that "we may not fully understand the breadth of (particulate matter) health burdens."

Bhatia concluded that controlling particulate matter is technically feasible, but needs "increased efforts to assess exposure at the community level, more stringent and creative regulatory initiatives, and political support."

Wellenius and colleagues studied links between daily variation in fine particulate matter – particles less than 2.5 micrometers in diameter – and stroke incidence in the Boston area.

They drew data from medical records of 1,705 patients admitted to a single institution with neurologist-confirmed ischemic stroke between April 1, 1999, and Oct. 31, 2008.

Fine matter concentrations were measured at a central monitoring station, using EPA guidelines that define moderate air quality as between 15 and 40 micrograms per cubic meter of air and good air quality as 15 micrograms or lower.

The study period included only days in which the air quality was good or moderate; the researchers excluded 11 days in which it exceeded 40 micrograms per cubic meter.

They found that the estimated odds ratio of ischemic stroke onset was 1.34 (95% CI 1.13 to 1.58) following a 24-hour period classified as moderate, compared with a period in which the air quality was good. The risk increase was significant at P<0.001.

They also found that the relationship between higher particulate levels and increased risk of stroke was linear, strongest within 12 hours of exposure, and was seen among patients with strokes caused by large-artery atherosclerosis or small-vessel occlusion but not cardioembolism.

The risk was more strongly associated with markers of traffic pollution – such as black carbon and NO₂ – than with particles linked to nontraffic sources, they reported.

Although the findings add to the evidence linking stroke and air pollution, there are some "unique" aspects, according to Robert Brook, MD, of the University of Michigan Ann Arbor, and Sanjay Rajagopalan, MD, of the Ohio State University Medical Center in Columbus.

Specifically, they noted in an accompanying commentary, "the extremely rapid increase in stroke risk is an important novel insight" that suggests that current regulatory focus on daily and yearly average concentrations may be missing the boat.

For the cognition study, Weuve and colleagues turned to the long-running Nurses' Health Study, which began in 1976 with more than 121,000 participants.

Between 1995 and 2001, participants 70 or older with no history of stroke were asked to take part in a study of cognition and 19,049 agreed. Cognitive testing was done by telephone three times, with about two years between interviews.

The researchers tracked changes in cognition, looking for associations between both fine and coarse particulate matter, defined, respectively, as smaller than 2.5 micrometers in diameter and between 2.5 and 10 micrometers.

Particulate matter was measured using EPA monitoring data, adjusted to estimate local exposure for each participant.

Analysis showed that higher levels of long-term exposure to both grades of pollution were associated with "significantly faster cognitive decline," the researchers found. Specifically:

• The two-year decline on a global score was 0.020 units worse for every increase of 10 micrograms per cubic meter in long-term exposure to coarse particles.
• Similarly, the two-year decline was 0.018 units worse for every increase of 10 micrograms per cubic meter in long-term fine particle exposure.

The differences, Weuve and colleagues reported, were similar to those between women in the study who were approximately two years apart in age.

The associations, they reported, were found at pollution levels typical in many areas, suggesting that pollution control might be a way to reduce the "future population burden of age-related cognitive decline, and, eventually, dementia."