Long-term exposure to air pollution is associated with a significantly increased risk of developing two serious forms of dementia, according to a new study that adds to growing evidence of the damage toxic air causes to the brain.
The research found that people exposed to higher levels of PM2.5 faced nearly four times the risk of developing dementia with Lewy bodies (DLB) and more than twice the risk of Parkinson’s disease-related dementia (PDD), compared with those exposed to lower levels.
Nitrogen dioxide, primarily produced by burning fossil fuels, was also associated with significantly elevated risk of both conditions.
The study was based on Danish national health registry data covering more than two million people aged between 65 and 95, tracking over 3,000 cases of DLB and nearly 3,800 cases of PDD diagnosed over a twenty-year period.
Researchers calculated each person’s average exposure to PM2.5 and NO2 over the ten years before their diagnosis and compared them with matched controls who did not develop the conditions.
Dementia with Lewy bodies and Parkinson’s disease-related dementia together account for up to a quarter of all dementia cases worldwide. Both are progressive, debilitating conditions associated with worse outcomes than many other forms of dementia, including a higher likelihood of nursing home placement and earlier death. Parkinson’s disease itself is currently the fastest growing neurodegenerative disease globally.
The researchers suggest that neuroinflammation, the brain’s immune response, may be one of the mechanisms through which air pollutants cause neurological damage. The particles crossing the blood-brain barrier may trigger chronic inflammation in brain cells, contributing to the protein deposits and neuronal damage that characterise these diseases.
One possibility highlighted in the paper is that pollutants may enter the brain via the olfactory system, which is known to be affected early in both conditions.
The researchers say more work is now needed to understand exactly how air pollution damages the brain and triggers these diseases, which could in turn open up new avenues for treatment and prevention.
The fill research can be read here.
Photo: geralt
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