Air pollution accelerates female brain ageing

LONG term exposure to particulate air pollution appears to accelerate cognitive decline, according to findings from a study in nearly 20,000 US women.

The prospective study drew on data from the Nurses’ Health Study Cognitive Cohort of women aged 70–81 years and evaluated their exposure to pollution from vehicular traffic, diesel powered equipment and other industrial emissions.

The researchers showed that higher levels of exposure to both course particulate matter (PM) and fine particulate matter (PM < 2.5µm in diameter) were associated with significantly faster cognitive decline.

The women were tested for general cognition, verbal memory, category fluency, working memory and attention.

The effect of a 10µg/m³increment in long term PM exposure was cognitively equivalent to ageing by approximately two years, they estimated. 

The association was present at levels of PM exposure typical in many areas of the United States, leading the researchers to suggest that reduction of air pollution could reduce the future burden of age-related cognitive decline, and even dementia.
 Other research has shown exposure to ambient fine PM is associated with higher risk of acute cardiovascular events, excess hospitalisations and deaths.

The researchers said PM may access the brain either through circulation or intranasally.

Animal studies have demonstrated increased brain inflammation and brain degeneration in response to particulate exposure.

Arch Intern Med 2012; 172:219-27