Improving air quality may boost brain function and reduce the risk of dementia, according to multiple studies.
This marks the first accumulated evidence which shows that reducing pollution is associated with a lower risk of all-cause dementia and Alzheimer's disease.
The new data showed that a reduction of fine particulate matter and traffic-related pollutants were found to decrease dementia risk, and slow cognitive decline, in U.S. women aged over 74, regardless of age, education, geography, or cardiovascular disease.
Meanwhile, a similar study in France revealed that reducing fine particulate matter over a decade was associated with a lower risk of all-cause dementia in individuals over the age of 65.
Christina Park, doctoral student in the Department of Epidemiology at the University of Washington, and her colleagues found that long-term exposure to air pollutants was associated with higher beta-amyloid levels in the blood.
Accumulation of beta-amyloid plaques is one of the hallmarks of Alzheimer's, and while previous studies found a relationship between air pollution and increased beta-amyloid production, little is known about the long-term effects of exposure.
However, it does show a possible biological connection between air quality and physical brain changes that define Alzheimer's.
"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."
Claire Sexton, Alzheimer's Association director of scientific programs and outreach, said: "We've known for some time that air pollution is bad for our brains and overall health, including a connection to amyloid buildup in the brain.
"But what's exciting is we're now seeing data showing that improving air quality may actually reduce the risk of dementia. These data demonstrate the importance of policies and action by federal and local governments, and businesses, that address reducing air pollutants."
The findings were reported at the Alzheimer’s Association International Conference (AAIC) in Denver, Colorado.