Air pollution by fine particles is a risk factor for Parkinson’s: American study | 25% increase in risk found in areas most exposed to long-term PM2.5

People living in areas with high levels of air pollutants called fine particulate matter (PM2.5) – sources of which include power plants, motor vehicles and fires – are at greater risk of Parkinson’s diseaseaccording to an American study.

“We found a nationwide association between Parkinson’s disease and exposure to air pollution, with people exposed to the highest levels of fine particulate matter having an increased risk of Parkinson’s disease compared to those exposed to the highest levels of fine particulate matter. people exposed to the lowest levels,” said Brittany Krzyzanowski, PhD, the study’s lead. author from the Barrow Neurological Institute in Arizona, said in a Press release from the American Academy of Neurology (AAN).

The Mississippi-Ohio River Valley is a particular “hot spot” for Parkinson’s disease, Krzyzanowski added, with “some of the highest levels of fine particle pollution in the country. »

The findings of the study, “Fine particulate matter and the risk of Parkinson’s disease in Medicare beneficiarieswill be presented at the 75th Annual Meeting of the AAN, which will take place in Boston and virtually from April 22-27.

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Fine particles consist of smoke, aerosols, soot, etc.

“By mapping national levels of Parkinson’s disease and linking them to air pollution, we hope to create a better understanding of regional risks and inspire leaders to take action to reduce disease risk by reducing levels air pollution,” Krzyzanowski said.

Both genetic and environmental factors appear to influence the risk of Parkinson’s disease, a progressive neurodegenerative disease widely known for its movement-related symptoms.

Growing evidence suggests air pollution is an environmental risk factor for Parkinson’s disease. A European report has also established a link between long-term exposure to air pollutants such as PM2.5 and greater risk of dying from Parkinson’s disease.

PM2.5 are particles less than 2.5 micrometers in diameter – about 30 times smaller than a human hair – made up of smoke, soot, aerosols, mold spores, dander, etc. These particles come from motor vehicles, power plants powered by fossil fuels, other industries, and forest and grass fires.

Krzyzanowski and colleagues studied potential links between higher PM2.5 exposure and Parkinson’s risk in the United States

“We used geographic methods to look at rates of Parkinson’s disease across the United States and compared those rates to regional air pollution levels,” Krzyzanowski said.

The researchers used 2009 data from Medicare, the government-funded health insurance program for people 65 or older and people with certain disabilities. Of the more than 22.5 million people enrolled in Medicare that year, 83,674 had been newly diagnosed with Parkinson’s disease.

Disease rates were mapped and calculated for several regions of the United States. Average levels of air pollution exposure, derived from annual PM2.5 concentrations, were established for this group of 2009 patients using their ZIP codes of residence and counties.

These people were then divided into four groups based on their average PM2.5 exposure. Those most exposed had an average annual exposure of 19 micrograms per cubic meter (mcg/m3), while those in the least exposed group were exposed, on average, to five mcg/m3 of PM2.5 each year.

Among people in the most exposed group, 434 out of 100,000 people received a new diagnosis of Parkinson’s disease, compared to 359 new cases in the least exposed group.

After adjusting for factors known to influence Parkinson’s risk, such as age, gender, race, smoking and use of medical care, the researchers found that disease risk increased by 25% between most exposed and most exposed groups.

Exposure Risks Noted in Rocky Mountain Region, Mississippi-Ohio River Valley

The researchers then divided PM2.5 exposure into 10 levels for more detailed geographical assessment.

The link between PM2.5 exposure and Parkinson’s risk was strongest in the Rocky Mountain region, which included Lake County, Colorado — southwest of Denver — and its neighboring counties. Moving from one level of exposure to another in these counties was associated with a 16% increase in the risk of Parkinson’s disease.

In the Mississippi-Ohio River Valley, which includes Tennessee and Kentucky, higher PM2.5 exposure was also linked to higher rates of Parkinson’s, but this association was weaker than in the Rocky Mountain region.

Here, the risk of Parkinson’s disease was 4% higher for each increase in exposure level.

“Finding a relatively weaker association where we have some of the highest PD risks and fine particulate levels in the country is consistent with the threshold effect we observed in our data,” Krzyzanowski said.

“In the Mississippi-Ohio River Valley, for example, the risk of Parkinson’s disease increases with increasing exposure to air pollution until about age 15. [mcg/m3] particulate matter, where the risk of Parkinson’s disease appears to plateau,” Krzyzanowski added.

The researchers noted that this weaker link may be due to an apparent plateau effect between 12 and 19 mcg/m3, and the fact that air pollution is also associated with an increased risk of other health problems, including dementia, which may affect the likelihood of a diagnosis of Parkinson’s.

“Using state-of-the-art geospatial analysis techniques, we identified a nationwide association between PD [Parkinson’s disease] and PM2.5, the strength of which varied by region,” the researchers wrote in the summary.

Since PM2.5 contains a variety of air pollutants, some more toxic than others, “further investigation of specific subfractions of PM2.5 may provide insight into the regional variability of the PM2 association. ,5-PD,” the team added.

This work was supported by the U.S. Department of Defense, the National Institute of Environmental Health Sciences, and the Michael J. Fox Foundation for Parkinson’s Disease Research.