Moderate level of fine particle pollution is associated with a 56 per cent higher risk of developing Parkinson's disease, new research in the US has found.
Previous studies have shown that fine particulate matter, or PM2.5, can cause inflammation in the brain, which is "a known mechanism by which Parkinson's disease could develop," according to lead researcher Brittany Krzyzanowski from Barrow Neurological Institute, Arizona.
The researchers also found that the relationship between air pollution and Parkinson's disease was not the same in every part of the country, and that it varied in strength by region. They have published their findings in the journal Neurology.
Parkinson's disease is a degenerative disorder of the central nervous system characterised by tremors and impaired muscular coordination.
In this study, the researchers identified nearly 90,000 people with the neurological disease from the US's Medicare dataset of about 22 million people. Those identified were then geocoded to the neighbourhood of their residence, which enabled the researchers to calculate the rates of the disease within each region.
The average annual concentrations of fine particulate matter in these specific regions were also calculated.
Thus, the researchers at Barrow 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.
They found that the Mississippi-Ohio River Valley was a Parkinson's disease hotspot, along with other US states including central North Dakota, parts of Texas, Kansas, eastern Michigan, and parts of Florida.
Further, people living in the western half of the US were found to be at a reduced risk of developing Parkinson's disease compared with the rest of the nation.
"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," said Krzyzanowski.
Although the authors had not explored the different sources of air pollution, Krzyzanowski noted there was relatively high road network density in the Mississippi-Ohio River Valley and the rust belt makes up part of this region as well.
"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," said the lead researcher.
The researchers said that such population-based geographic studies had the potential to reveal important insight into the role of environmental toxins in the development and progression of Parkinson's.
"These same methods can be applied to explore other neurological health outcomes as well," said Krzyzanowski.
The team hopes that the study findings will help enforce stricter policies aimed at lowering air pollution levels and decreasing the risk for Parkinson's disease, and other associated illnesses.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
