Study Links Air Pollution to Increased Risk of Dementia

New Delhi: A new study published in The Lancet Planetary Health has found that long-term exposure to air pollution, especially from sources such as vehicle exhaust and wood burning, can significantly increase the risk of developing dementia.

The research, which involved a comprehensive analysis of existing studies, highlights a strong association between air pollutants like PM2.5 (particulate matter with a diameter of 2.5 microns or less), nitrogen dioxide (NO₂), and soot, with the onset and progression of dementia. PM2.5 is commonly found in emissions from cars, industrial processes, and burning wood.

The findings suggest that for every 10 micrograms per cubic metre of PM2.5 exposure, the relative risk of developing dementia increases by 17 per cent. Similarly, exposure to just 1 microgram per cubic metre of soot was linked to a 13 per cent increase in dementia risk. Soot particles, like PM2.5, primarily come from exhaust emissions and biomass burning.

Dementia, including Alzheimer’s disease, already affects over 57.4 million people globally—a number projected to almost triple to 152.8 million by 2050. The study indicates that addressing environmental factors could be a critical component of dementia prevention.

"These findings underscore the need for an interdisciplinary approach to dementia prevention," said Dr. Christiaan Bredell from the University of Cambridge, one of the study’s joint first authors. "Preventing dementia is not just the responsibility of health care. Urban planning, transport policy, and environmental regulation all have a role to play."

Air pollution contributes to brain inflammation and oxidative stress, which can damage brain cells and accelerate cognitive decline. According to Dr. Haneen Khreis from the MRC Epidemiology Unit, reducing air pollution could bring substantial benefits for public health, lessen the burden on healthcare systems, and provide broader social and economic gains.

The research team conducted a systematic review and meta-analysis of 51 studies involving data from over 29 million participants, primarily from high-income countries. Of these, 34 studies were included in the meta-analysis, originating from North America, Europe, Asia, and Australia.

Importantly, the analysis showed that the impact of air pollution was particularly strong in cases of vascular dementia, which occurs due to reduced blood flow to the brain. This reinforces the importance of clean air initiatives as a public health priority, especially in urban areas with high traffic emissions.