Air pollution and risk of dementia

Exposure to a traffic-related air pollutant significantly increases risk for dementia, new research suggests.

Results from a meta-analysis, which included a total of more than 90 million people, showed risk for dementia increased 3% for every 1 microgram per cubic meter rise in fine particulate matter (PM2.5) exposure.

Particulate matter is a mixture of solid particles and liquid droplets from the burning of fossil fuels and nitrogen oxide, and also produced from road traffic exhaust.

Researchers analyzed data from 17 studies with a total of 91.4 million individuals, 6% of whom had dementia. In addition to PM2.5, the investigators also assessed nitrogen oxides, which form smog, nitrogen dioxide, and ozone exposure.

After adjustments for other known risk factors, such as age and gender, results showed that dementia risk increased by 3% for every 1 cubic meter rise in PM2.5 exposure (adjusted hazard ratio [aHR], 1.03; 95% CI, 1.02 - 1.05).

The clear link between fine particulate matter exposure and increased risk emphasizes the need to address air pollution as a modifiable risk factor for dementia..

Results from a study published earlier this year estimated that rates of dementia will triple worldwide and double in the US by 2050 unless steps are taking to mitigate risk factors.