Long-term air pollution exposure linked to higher dementia risk, study finds

A new study by researchers from Aarhus University and the University of Florida suggests prolonged exposure to air pollution may significantly increase the risk of developing two types of dementia.

The study, which analysed data from 2.1 million Danes aged 65–95, found that fine particulate matter and nitrogen dioxide—common pollutants from traffic, shipping, and combustion—were associated with higher rates of Lewy body dementia and Parkinson’s-related dementia, according to a press release from Aarhus University Hospital.

“These are pollutants that most people are exposed to every day,” said Dimitry S. Davydow, a psychiatrist and professor at the University of Florida’s Norman Fixel Institute.

Researchers tracked air pollution levels at participants’ residential addresses over a full decade before their dementia diagnoses. The findings showed that even modest increases in pollution correlated with sharply higher risks:

A 5 µg/m³ rise in fine particulate matter was linked to nearly four times the risk of Lewy body dementia and more than double the risk of Parkinson’s-related dementia. A 10 µg/m³ increase in nitrogen dioxide also raised the risk for both conditions, though the effect was less pronounced than for fine particles.

Jakob Christensen, a senior consultant at Aarhus University Hospital and professor at Aarhus University, noted that while the study had limitations—such as lacking data on lifestyle factors like smoking—it still pointed to a potential connection between long-term pollution exposure and brain health.

“Our results suggest that air pollution may be one of the environmental factors contributing to the development of these diseases,” Christensen said.