July 26 (UPI) -- Improving air quality may also improve cognitive function and reduce risk for dementia, according to a series of studies that will be presented this week at the Alzheimer Association International Conference.
While previous studies have linked long-term pollution with an accumulation of Alzheimer's disease-related brain plaques, researchers say the new studies are the first to prove the link.
In a press release on Monday, the AAIC called both the increase of air pollution and cases of dementia worldwide public health crises.
"We've known for some time that air pollution is bad for our brains and overall health ... but what's exciting is we're now seeing data showing that improving air quality may actually reduce the risk of dementia," Claire Sexton, Alzhiemer's Association director of scientific programs and outreach, said in the press release.
Key findings in the recent studies found that reductions in fine particulate matter and traffic-related pollutants over 10 years were associated with 14% and 26% reductions in dementia risk in older U.S. women, and reductions in the risk of dementia in French people by 15%.
Dr. Xinhui Wang, assistant professor of research neurology at University of Southern California, investigated whether reductions in air pollution may have slower decline in their cognitive function and be less likely to develop dementia.
Wang studied women age 79 to 92 in the United States who didn't have dementia at the beginning of the study.
The participants were followed between 2008 and 2018 and tests were done every year to determine whether they developed dementia. Air pollution at their recorded home addresses was also studied.
They found that air quality improved greatly over 10 years and that the risk of dementia decreased up to 26%.
"Our findings are important because they strengthen the evidence that high levels of outdoor air pollution in later life harm our brains," Wang said. "The possible benefits found in our studies extended across a variety of cognitive abilities, suggesting a positive impact on multiple underlying brain regions."
Another study, conducted by Noemie Letellier, a postdoctoral scholar at the University of California, reviewed data on more than 7,000 people, finding that a reduction of fine particulates is associated with a reduced risk of dementia in French adults.
Researchers observed reductions of PM2.5 concentrations between 1990 and 2000, linking it to a 15% reduced risk of all-cause dementia.
Additionally, a study involving more than 3,000 dementia-free people looked at links between long-term air pollution and increased beta-amyloid plaques was conducted by Christina Park, a doctoral student at the University of Washington.
Researchers analyzed air pollution near study participants' homes as part of the Gingko Evaluation Memory Study, following them for periods up to 20 years, and measuring beta-amyloid in their blood along the way.
The study is the first suggesting long-term exposure to air pollutants is associated to higher beta-amyloid levels in the blood, the researchers said.
"Our findings suggest that air pollution may be an important factor in the development of dementia," Park said.
"Many other factors that impact dementia are not changeable, but reductions in exposure to air pollution may be associated with a lower risk of dementia. More research is needed," Park said.