Fine-particulate air pollution can drive devastating forms of dementia by triggering toxic protein clumps that destroy nerve cells, research suggests. The study, published in Science, identifies a link between long-term exposure to PM2.5 particles and Lewy body dementia, the third most common dementia after Alzheimer's and vascular dementia.
Researchers analysed hospital records of 56.5 million US Medicare patients admitted between 2000 and 2014. Using patients' zip codes, they estimated long-term PM2.5 exposure and found it raised the risk of Lewy body dementia, with less impact on other neurodegenerative diseases.
In mouse experiments, exposure to PM2.5 every other day for 10 months caused nerve cell death, brain shrinkage, and cognitive decline in normal mice. Genetically modified mice unable to produce the protein alpha-synuclein were largely unaffected. The toxic clumps formed in normal mice closely resembled human Lewy bodies.
Lead investigator Dr Xiaobo Mao of Johns Hopkins University said: “Unlike age or genetics, this is something we can change. The most direct implication is that clean air policies are brain health policies.” The study calls for reduced emissions from industry, vehicle exhausts, and wood burning, as well as better wildfire management.
Prof Charles Swanton of the Francis Crick Institute, part of the Rapid project investigating air pollution and dementia, said: “This is an important and compelling study that deepens our understanding of how air pollution can drive neurodegenerative disease.”
