The air you breathe does more than affect your lungs.
A new study published this week found that older women exposed to air polluted by vehicle exhaust and other damaging particles are almost twice as likely to develop dementia. Others who carried a specific gene were almost four times likelier to develop loss of memory and reasoning skills.
“Although the link between air pollution and Alzheimer's disease is a new scientific frontier, we now have evidence that air pollution, like tobacco, is dangerous to the aging brain,” said study co-senior author Caleb Finch in a statement. Finch works at the University of Southern California's Leonard Davis School of Gerontology.
Specifically, USC researchers found that older women living in areas where air pollution particles exceed federal safety standards may face an 81 percent higher risk for cognitive decline. They also have a 92 percent greater likelihood of developing dementia, including Alzheimer's disease.
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The detrimental effects of air pollution — which includes tiny particles emitted by motor vehicles, power plants and the burning of biomass products such as wood — were also worse in women who carry APE-e4, a gene variant that increases their risk of developing Alzheimer’s.
The nationwide study, published in the journal Translational Psychiatry, examined 3,600 women who were between the ages of 65 and 79. None of them had dementia at the beginning of the study. Researchers also looked at female lab mice and at brain tissue in petri dishes.
In comparing those who breathed clean air and those exposed to unsafe pollution levels, results for all three groups suggested that exposure to air pollutants increased disorientation and memory loss as well as amyloid beta protein clumps in the brain. Researchers used air pollution standards set by the U.S. Environmental Protection Agency.
Applying their findings to the general population, the USC researchers calculated that air pollution might be to blame for about 21 percent of all cases of dementia.
But they also cautioned that the study does not prove definitively that air pollution causes the risk of dementia to rise. What’s more, results from animals don’t always produce similar results in humans..
Past research has already shown the effects of air pollution on lung disease and cardiovascular disease, but this most recent study provides more insight into how it may affect the aging brain. A study published in 2011 also found that people who lived close to densely trafficked roads were at a far higher risk of stroke and dementia than those who lived farther away. A year later, a team at Mount Sinai in New York first established that air pollutants induced inflammation, cell death and the buildup of amyloid protein in the brains of mice.