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Scientists have proven that air pollution and cognitive decline involving humans and mice provide evidence that cleaner air may reduce the risk for Alzheimer’s and other dementias.
Two researchers at the University of Southern California whose work linked air pollution to a greater risk of Alzheimer’s disease and faster cognitive decline are seeing signs that cleaner air can make a difference in brain health.
Automobiles and factories produce a particulate known as PM2.5 that USC-led studies have linked to memory loss and Alzheimer’s disease. Smaller than the width of human hair, these tiny particles pose a major threat to your health. When inhaled, they pass directly from the nose up and into the brain, beyond the blood-brain barrier that normally protects the brain from dust or other invaders.
In a research publication, Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, the USC researchers described how their labs each independently reported indications of recent decreases in neurotoxicity (damage to the brain or nervous system caused by exposure to toxic substances) of PM2.5 air pollution in humans and mice.
University Professor Caleb Finch and Associate Professor Jennifer Ailshire, both with the USC Leonard Davis School of Gerontology, focused on PM2.5 pollution. The small particulate is absorbed both by our lungs and blood. Long-term exposure to PM2.5 has been linked to premature death, particularly in people with chronic heart or lung diseases.
Improving air quality may have cognitive benefits
Research from Jennifer Ailshire, published in the Journal of Alzheimer’s Disease, also found evidence of lower neurotoxicity of air pollution over time.
Finch and his research team have studied pollution levels at the same Los Angeles site and their effect on mouse brains since 2009. After 2017, the mice exposed to a nanoscale version of PM2.5 appeared healthier. Also, they showed sharp declines in several factors of neurotoxicity, including oxidative damage to cells and tissues.
During the years that Finch’s and Ailshire’s studies were taking place, the composition of air pollution in the United States was also changing.
From 2000 to 2020, the PM2.5 levels declined nationwide by 41% according to the EPA. In contrast, urban PM2.5 in Los Angeles declined only slightly from 2009 to 2019. While nationwide ozone levels decreased, Los Angeles County ozone reversed the prior trends by increasing after 2015.
Finch and Ailshire emphasize that their findings cannot evaluate the potential benefits of air pollution improvements to the risk of cognitive decline and dementia. Although PM2.5 levels declined nationally from 2009 to 2016, the year-over-year increases that have been observed since 2017 show that improvements in air quality can be reversed, as they were in Los Angeles.
“Our findings underscore the importance of efforts to improve air quality as well as the continued importance of demographic and experimental evaluation of air pollution neurotoxicity,” said Finch.
Finch and Jiu-Chiuan “J.C.” Chen, an associate professor of population and public health sciences at the Keck School of Medicine of USC, published a study using both human and animal data that showed brain aging processes worsened by air pollution may increase dementia risk. Their research indicated that older women who lived in locations with high levels of PM2.5 suffered memory loss and Alzheimer’s-like brain shrinkage not seen in women living with cleaner air.
Who to turn to
How does outdoor air affect your indoor air quality? Through open doors and windows, outdoor pollutants enter your occupied spaces. We spend nearly 90% of our time indoors and without maximum air filtration, the air we breathe indoors can be up to 5 times more polluted than outdoor air. As pollution outdoors increases, the best way to combat health issues associated with pollution is to clean the air you breathe indoors through different methods of filtration and purification. Fresh Air Matters offers local plans and services, as well as air purifiers that are proven to capture, remove, and eliminate the indoor airborne allergens, pollutants, and contaminants negatively affecting your indoor air quality and overall health.