Dementia in Women from Air Pollution Toxins

A growing body of evidence over the last few years has demonstrated that air pollution is a significant risk factor for developing dementia in old age. “These ‘toxic’ responses can make the blood-brain barrier leaky and cause damage to the brain,” says Dr. Jiu-Chiuan Chen, neuroscientist, University of Southern California. Now results from a new scientific study suggest what many scientists have been discovering in recent years: Improved air quality over several years is associated with a reduced risk of dementia in elderly women.

The findings bolster suspicions that external pollutants can contribute to accelerated aging in the brain (which is effectively what dementia is)*. But more critically, they also show that this aging can be slowed down if exposure to those pollutants decreases.

Study overview

Researchers assessed the annual physical and cognitive health of 2,239 US women aged 74 to 92, from 2008 to 2018.  They focused on women because they are disproportionately affected by degeneration nervous diseases such as Alzheimer’s, which can lead to dementia. These women were geographically spread across the country, and all were dementia-free from at least 2008 to 2012. The researchers compared these assessments to average annual concentrations of outdoor pollution from 1998 to 2012 to determine locations where air quality was trending toward health levels. The study focused on measurements of fine particulate matter and nitrogen dioxide – two very common traffic exhaust pollutants.

Results overview

During the 10 year study period, 398 women were diagnosed with dementia. But the researchers found that locations with greater improvements in air quality showed fewer cases of dementia diagnoses among the women who participated in the study. While reducing risk varies depending on other factors, the researchers explained that reducing air pollution exposure to nearly 15 percent below the EPA’s current standard limit resulted in a 20 percent reduction in dementia risk.

Moreover, the link between reduced risk of dementia and improved air quality did not differ significantly by age, education, geography, or cardiovascular risk factors, suggesting that air pollution does indeed play a greater role in dementia than previously thought.


The data from the most recent study indicate that large reductions in air pollution reduce the likelihood that women ages 74 to 92 years will develop dementia, or memory loss and declines in brain function by up to 20% as they age. The decline in dementia risk for women in this group associated with improvement in air quality was equivalent to adding nearly 2-1/2 years to their age.

*Also See: How air pollution threatens brain health,


The impact of exposure to air pollution on cognitive performance,



Air pollution interacts with genetic risk to influence cortical networks implicated in depression

Li, et al.

Journal reference:  This scientific publication issue is currently being compiled. A full reference for this article in the final version of record will be published here as soon as it is ready:  Chen, J. et al., Proceedings of the National Academy of Sciences (PNAS),