Everyone knows cleaner air means healthier bodies, but new research suggests it might also help aging minds.
"Our study is important because it is one of the first to show that reducing air pollution over time may benefit the brain health of older women by decreasing their likelihood of developing dementia," said study co-lead author Xinhui Wang. Wang is assistant professor of research neurology at the University of Southern California's Keck School of Medicine, in Los Angeles.
Previous research had linked exposure to air pollution later in life with an increased risk of dementia, but how improved air quality affects brain health wasn't clear.
To find out, the researchers analyzed data from more than 2,200 U.S. women (aged 74 to 92) who had yearly tests of mental functioning between 2008 and 2018 as part of a long-term study. They did not have dementia when the study began.
The researchers used the women's home addresses to estimate their exposure to air pollution over the period.
Those living in areas with the greatest declines in two air pollutants -- fine particulate matter and the traffic-related pollutant nitrogen dioxide -- saw their risk of dementia fall by 14% and 26%, respectively, according to findings published online Jan. 11 in the Proceedings of the National Academy of Sciences.
Although the study could not prove a cause-and-effect relationship, the brain benefit associated with cleaner air was consistent regardless of age, economic status, heart disease risk factors and a genetic risk factor for dementia and Alzheimer's known as apolipoprotein E genotype.
"The takeaway message is that reducing air pollution exposure can promote healthier brain aging," Wang said in a university news release.
Dementia disproportionately affects women, the study authors noted.
Co-lead study author Diana Younan, a former senior research associate at the Keck School, said Alzheimer's disease and related dementias are immensely costly to the health care system and to families.
"Our research suggests that tightening the air quality standards may help to prevent Alzheimer's disease and related dementias in older women and, in turn, reduce its societal burden," she said.
Alzheimers.gov has more on reducing dementia risk.
SOURCE: University of Southern California, news release, Jan. 10, 2022