Summary: Exposure to air pollution has previously been linked to an increased risk of Alzheimer’s disease. Now researchers are providing preliminary data linking air pollution to an increased risk of Parkinson’s disease. The new study, which took into account geographic data and rates of Parkinson’s disease diagnosis, found that those who live in the Mississippi-Ohio River Valley are at particularly high risk of being diagnosed with the disease. of Parkinson’s.
According to a preliminary study published today, February 23, 2023, which will be presented at the American Academy of Neurology’s 75e The annual meeting will be held in person in Boston and live online April 22-27, 2023.
The study focused on fine particles, PM2.5, which measure less than 2.5 microns in diameter. Fine particles come from motor vehicle exhaust, the combustion of fuels by power plants and other industries, and forest and grass fires.
“We used geographic methods to look at rates of Parkinson’s disease in the United States and compared them to regional levels of air pollution,” said study author Brittany Krzyzanowski, PhD, of the Barrow Neurological Institute in Phoenix, Arizona.
“We found a nationwide association between Parkinson’s disease and air pollution exposure, with people exposed to the highest levels of fine particulate matter having an increased risk of Parkinson’s disease compared to people exposed to the highest levels. the lowest.
“We also identified a Parkinson’s disease hotspot in the Mississippi-Ohio River Valley, which is an area that has some of the highest levels of fine particulate pollution in the nation.”
The study involved more than 22.5 million people enrolled in Medicare in 2009. From this group, the researchers identified 83,674 people with Parkinson’s disease. Researchers mapped where study participants lived in the United States and calculated rates of Parkinson’s disease for various regions.
The researchers also calculated average levels of air pollution exposure for study participants using the zip codes and counties they lived in as well as an air pollution data source. on the average annual concentrations of fine particles.
The researchers then divided the participants into four groups based on average exposure to air pollution. People in the most exposed group had an average annual exposure of 19 micrograms per cubic meter (µg/m3) of fine particles. People in the least exposed group had an average annual exposure of five µg/m3.
In the most exposed group, 434 new cases of Parkinson’s disease developed per 100,000 people, compared to 359 cases in the least exposed group.
After adjusting for other factors that may affect the risk of Parkinson’s disease, such as age, smoking and use of medical care, the researchers found an association between Parkinson’s disease and average annual exposure to fine particles, with people in the most exposed group having a 25% increased risk of Parkinson’s disease compared to people in the least exposed group.
For geographic analysis, the researchers divided exposure to fine particles into 10 levels.
The researchers found the strongest association between air pollution and Parkinson’s disease in the Rocky Mountain region, which includes Lake County, Colorado, southwest of Denver, and its surrounding counties. The risk of Parkinson’s disease in these counties increased by 16% when passing a level of exposure to fine particles to the next level.
Air pollution was also associated with higher rates of Parkinson’s disease in the Mississippi-Ohio River Valley hotspot, which includes Tennessee and Kentucky, but the association was weaker in those regions. , with a 4% increase in risk when passing a fine level. exposure to fine particles to the next.
“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 up to about 15 µg/m3 of fine particulate matter, where the risk of Parkinson’s disease seems to level off.
Krzyzanowski said: “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. reducing air pollution levels.
A limitation of the study was that it focused on fine particulates, which contain a variety of air pollutants, some of which may be more toxic than others. Krzyzanowski noted that air pollution is also associated with a variety of other health risks, including dementia, which could decrease the likelihood of a Parkinson’s diagnosis, and this may explain the relatively higher association. weak between Parkinson’s disease and particles in the Mississippi-Ohio River Valley. .
Funding: The study was supported by the US Department of Defense, the National Institutes of Health, including the National Institute for Environmental Health Sciences, and the Michael J. Fox Foundation for Parkinson’s Disease Research.
About this air pollution and Parkinson’s disease research news
Author: Nathalie Conrad
Contact: Natalie Conrad – Ont.
Picture: Image is in public domain
Original research: The results will be presented at the American Academy of Neurology’s 75e Annual meeting