A team of researchers at Johns Hopkins Medicine has uncovered new evidence that connects air pollution to brain changes linked to Lewy body dementia, a serious and currently incurable condition.
Lewy body diseases, which include Parkinson’s disease and Lewy body dementia, are marked by abnormal clumps of a protein called alpha-synuclein. These clumps, known as Lewy bodies, interfere with normal brain function and cause symptoms such as memory problems, confusion, and movement difficulties.
The research, which builds on years of research showing that PM2.5 is linked to a higher risk of dementia, involved analysing hospital records from more than 56 million U.S. patients. It was found that people living in areas with higher levels of PM2.5 pollution were significantly more likely to develop Lewy body-related conditions.
Each increase in pollution levels was linked to a 17% higher risk of Parkinson’s disease dementia and a 12% higher risk of dementia with Lewy bodies.
Co-author of the study, Xiao Wu, of Columbia University, said: ‘The statistical association we uncovered is even stronger than what previous studies found when lumping all Alzheimer’s and related dementias together — highlighting Lewy body formation as a potentially pivotal pathway that warrants deeper biological investigation.’
To explore why this happens, the team exposed mice to PM2.5 over several months. In normal mice, pollution triggered brain shrinkage, cell death and memory decline – similar to what’s seen in Lewy body dementia. In contrast, mice genetically engineered to lack the alpha-synuclein protein did not show these changes.
Lead investigator Xiaobo Mao, Ph.D., of Johns Hopkins said: ‘We have identified a novel strain of Lewy bodies formed after exposure to air pollution. By defining this strain, we hope to establish a specific target for future drugs aimed at slowing the progression of neurodegenerative diseases marked by Lewy bodies.’
Importantly, the effects were consistent across samples of pollution collected from China, Europe, and the U.S., suggesting PM2.5 may have similar harmful impacts worldwide.
Shizhong Han, Ph.D., lead investigator at the Lieber Institute said: ‘This suggests that pollution may not only trigger the build-up of toxic proteins but also drive disease-related gene expression changes in the human brain.’
While genetic factors play a significant role in neurodegenerative disease, the researchers say people can potentially control their exposure to pollution.
Xiaodi Zhang, Ph.D., a first author of the study and postdoctoral fellow at the school of medicine, added: ‘Our next goal is to figure out which specific components in air pollution are driving these effects. Understanding that could help guide public health efforts to reduce harmful exposures and lower the risk of disease.’
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