Reducing Air Pollution Could Lower Risk for Dementia and Alzheimer's

Cutting down on ambient air pollution can reduce the risk for devastating cognitive ailments such as dementia and Alzheimer's disease in old age, according to the results of two new studies.

While pollution exposure is something of an occupational hazard of everyday life in modern big cities and towns, it negatively affects the body and mind in a number of ways.

Breathing in pollutants, especially those that result from the burning of fuel and those so small they are invisible to the naked eye, has been associated with increased risk for a diverse cross-section of diseases, disorders, and other conditions, including but not limited to: mouth cancer, poor bone health and mental illnesses such as bipolar disorder and major depression. In addition, it has been linked to the aggregation of Alzheimer's disease-associated protein fragments in the brain, according to a press release issued by the Alzheimer's Association.

Presented at the Alzheimer's Association International Conference 2021 in Denver on Monday, the new studies are the first to indicate that the reverse is true as well.

"These data demonstrate the importance of policies and action by federal and local governments, and businesses, that address reducing air pollutants," Claire Sexton, the Alzheimer's Association's director of scientific programs and outreach, said in the release.

The first of the studies focused on the impact of improved air quality on cognitive function in women ages of 74 to 92 in the United States, according to the release. Lead author Xinhui Wang, PhD, and colleagues followed individuals from 2008 to 2018. Their investigation revealed that individuals in locations that had a more significant reduction in air pollution experienced slower cognitive decline and were less likely to develop dementia than individuals in locations that had a comparatively negligible reduction in pollution.

Similarly, the second study found that a reduction in fine particulate matter—a particularly dangerous form of air pollution—was correlated with a decline in dementia and Alzheimer's risk in older French adults.

"Our findings are important because they strengthen the evidence that high levels of outdoor air pollution in later life harm our brains, and also provide new evidence that by improving air quality we may be able to significantly reduce risk of cognitive decline and dementia," Wang said, according to the release. "The possible benefits found in our studies extended across a variety of cognitive abilities, suggesting a positive impact on multiple underlying brain regions."

In 2021, Bangladesh, Pakistan, Mongolia, Afghanistan, India, Indonesia, Bahrain, Nepal, Uzbekistan, and Iraq ranked among the most polluted countries on Earth, according to the website World Population Review. In a 2018 effort to improve air quality in the Indian capital of New Delhi, the Dubai-based architecture firm Znera Space proposed erecting 330-foot towers around the city to filter particles from the air.

Smog hovers over Jakarta, Indonesia.
Improved air quality was recently associated with reduced risk for dementia and Alzheimer's disease. Pictured, smog hovers over Jakarta, Indonesia. The country is among the most polluted on earth. BAY ISMOYO/AFP/Getty Images