New research links air pollution to Parkinson’s Disease

New research, funded by the Michael J. Fox Foundation for Parkinson’s Research, the U.S. Department of Defense and the National Institute of Environmental Health Science claims to have identified a link between air pollution and Parkinson’s disease. 

Researchers at Barrow Neurological Institute found that people living in regions with median levels of air pollution have a 56% greater risk of developing Parkinson’s disease compared to those living in regions with the lowest level of air pollution.

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Brittany Krzyzanowski, PhD, a researcher at Barrow Neurological Institute, who led the study said: ‘Previous studies have shown fine particulate matter to cause inflammation in the brain, a known mechanism by which Parkinson’s disease could develop. Using state-of-the-art geospatial analytical techniques, we were, for the first time, able to confirm a strong nationwide association between incident Parkinson’s disease and fine particulate matter in the U.S.’

The population-based geographic study identified nearly 90,000 people with Parkinson’s disease from a Medicare dataset of nearly 22-million. Those identified with having Parkinson’s disease were geocoded to the neighborhood of residence, enabling researchers to calculate the rates of Parkinson’s disease within each region.

The average annual concentrations of PM2.5 in these regions were also calculated. After adjusting for other risk factors, the researchers were able to identify an association between a person’s previous exposure to fine particulate matter and their later risk of developing Parkinson’s disease.

The study found that the relationship between air pollution and Parkinson’s disease differs around the country, but as the main pollutant being studied was PM2.5, its chemical composition is likely to vary from area to area. The Mississippi-Ohio River Valley was identified as a Parkinson’s disease hotspot, and here studies have identified heavy metals within PM2.5, including manganese and zinc linked to iron and steel manufacturing. 

Krzyzanowski said: ‘Regional differences in Parkinson’s disease might reflect regional differences in the composition of the particulate matter. Some areas may have particulate matter containing more toxic components compared to other areas. This means that the pollution in these areas may contain more combustion particles from traffic and heavy metals from manufacturing which have been linked to cell death in the part of the brain involved in Parkinson’s disease.’

Other hotspots were found in central North Dakota, parts of Texas, Kansas, eastern Michigan, and the tip of Florida. People living in the western half of the U.S. are at a reduced risk of developing Parkinson’s disease compared with the rest of the nation.

The research also found that while the risk of Parkinson’s disease increased up to 13 µg/m³, it tended to plateau out at this level. This, the team say, is significant:  ‘Recently, the U.S. Environmental Protection Agency proposed to revise the primary (health-based) annual PM2.5 standard level from 12 µg/m³ to 9-10 µg/m³ due to growing evidence of health effects at levels lower than the previous regulatory standard. Our study provides important additional evidence supporting this proposal.’

Read the full study here


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