New study links air pollution to dementia

A recent study published in the journal JAMA Network Open reveals that an estimated 188,000 cases of dementia in the US each year could potentially be attributed to air pollution.

The research highlights a significant correlation between poor air quality, particularly from wildfires and agricultural sources, and an increased risk of developing Alzheimer's disease and other forms of dementia later in life.

While previous research has established a connection between overall poor air quality and various health issues, including dementia, this study offers a more nuanced understanding of how specific sources of air pollution exhibit stronger links to dementia.

The research drew from extensive data collected through a decades-long survey supported by the National Institutes of Health. This survey tracked the health of older adults across the country every two years. By merging this data with detailed air quality modeling, researchers evaluated the potential exposure of individuals to specific air pollutants based on their geographical locations.

The study concentrates on PM 2.5 air pollution, composed of particles less than 2.5 micrometers wide, which can be inhaled and can originate from sources like vehicle emissions and wildfire smoke. These particles are associated with a range of health issues, including breathing difficulties, worsening asthma, and even increased mortality due to heart disease.

The research team accounted for various air pollution sources, including emissions from coal-fired power plants, agricultural activities, wildfires and traffic. Their modelling revealed a heightened risk of dementia even after adjusting for factors such as sex, race, ethnicity, education and wealth. The study also considered whether participants had previously lived in urban or rural areas.

Highlighting the progressive nature of dementia, the study's lead researcher, Sara Adar, explains how it develops over a lifetime rather than as an immediate consequence of recent exposures. 

In addition to analyzing direct emissions from sources like wildfires and agriculture, the study accounted for other forms of air pollution indirectly associated with these sources. Toxic substances carried by wildfire smoke and ammonia released during farming activities were identified as contributing factors to brain-damaging particles in the air.

Adar and Boya Zhang, fellow researchers, believed their findings could pave the way for targeted interventions to mitigate the risk of dementia linked to air pollution. Unlike other risk factors for dementia that may be more challenging to address, air pollution is a modifiable factor that can be tackled on a larger scale, making it an appealing focus for widespread prevention efforts.