Air Pollution Can Drive Devastating Forms of Dementia, Research Suggests

An anonymous reader quotes a report from The Guardian: Fine-particulate air pollution can drive devastating forms of dementia by triggering the formation of toxic clumps of protein that destroy nerve cells as they spread through the brain, research suggests. Exposure to the airborne particles causes proteins in the brain to misfold into the clumps, which are hallmarks of Lewy body dementia, the second most common form of dementia after Alzheimer's disease. The finding has 'profound implications' for preventing the neurodegenerative disorder, which affects millions worldwide, with scientists calling for a concerted effort to improve air quality by cutting emissions from industrial activity and vehicle exhausts, improving wildfire management and reducing wood burning in homes.

The researchers began by analyzing hospital records of the 56.5 million US Medicare patients. They looked at those who were admitted for the first time between 2000 and 2014 with the protein damage. Armed with the patients' zip codes, the scientists estimated their long-term exposure to PM2.5 pollution, airborne particles that are smaller than 2.5 thousandths of a millimeter. These can be inhaled deep into the lungs and are found in the bloodstream, brain and other organs. They found that long-term exposure to PM2.5 raised the risk of Lewy body dementia, but had less of an impact on rates of another neurodegenerative brain disease that is not driven by the toxic proteins. Lewy bodies are made from a protein called alpha-synuclein. The protein is crucial for healthy brain functioning, but can misfold in various ways to produce different kinds of harmful Lewy bodies. These can kill nerve cells and cause devastating disease by spreading through the brain.

To see if air pollution could trigger Lewy bodies, the team exposed mice to PM2.5 pollution every other day for 10 months. Some were normal mice, but others were genetically modified to prevent them making alpha-synuclein. The results were striking: in normal mice, nerve cells died off, leading to brain shrinkage and cognitive decline. The genetically modified mice were largely unaffected. Further work in mice showed that PM2.5 pollution drove the formation of aggressive, resilient and toxic clumps of alpha-synuclein clumps that looked very similar to Lewy bodies in humans. Although the work is in mice, the findings are considered compelling evidence. The work has been published in the journal Science.

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