Exposure to certain forms of air pollution has been linked to an increased risk of developing dementia, according to the most comprehensive study conducted to date. This alarming research highlights that dementia currently affects an estimated 57 million people worldwide, with projections indicating that the number of cases could soar to at least 150 million by 2050. The findings were produced by researchers at the Medical Research Council’s epidemiology unit at the University of Cambridge and involved a systematic review of 51 studies.
The study drew on data from over 29 million participants who had been exposed to various air pollutants for a minimum of one year. While previous studies had identified air pollution as a potential risk factor for dementia, this research established a positive and statistically significant association between three specific types of air pollutants and the onset of dementia.
The primary pollutants identified in the study included:
PM2.5: These fine particles arise from vehicle emissions, power plants, and wood-burning stoves. Nitrogen dioxide: This gas is produced from the burning of fossil fuels. Soot: This pollutant originates from sources like vehicle exhaust and burning wood.When inhaled, these pollutants can penetrate deep into the lungs, leading to various respiratory diseases and increasing the risk of heart-related issues. The study revealed that for every 10 micrograms per cubic meter of PM2.5, an individual's relative risk of developing dementia increases by 17%. Additionally, the risk associated with soot was found to rise by 13% under similar conditions.
In 2023, pollution levels of both soot and PM2.5 approached or exceeded these concerning thresholds in urban areas such as central London, Birmingham, and Glasgow. This poses a significant public health concern, particularly as dementia continues to be a prevalent issue, with approximately 982,000 individuals affected in the UK alone. Common symptoms of dementia include memory loss, difficulty concentrating, and mood changes.
Dr. Haneen Khreis, the senior author of the study, emphasized that it provides further evidence supporting the notion that long-term exposure to outdoor air pollution is a significant risk factor for the onset of dementia in previously healthy adults. She stated, “Tackling air pollution can deliver long-term health, social, climate, and economic benefits. It can reduce the immense burden on patients, families, and caregivers, while easing pressure on overstretched healthcare systems.”
The researchers suggest that air pollution may contribute to dementia development through mechanisms such as brain inflammation and oxidative stress. Oxidative stress is a chemical process within the body that can lead to damage in cells, proteins, and DNA, further compromising cognitive health.
It's worth noting that the report has limitations, as the majority of studies analyzed predominantly included participants who were white and residing in high-income countries. The researchers advocate for future studies on air pollution to incorporate a more diverse participant pool, especially from marginalized backgrounds.
Dr. Isolde Radford, senior policy manager at Alzheimer’s Research UK, commented on the findings, stating, “This rigorous review adds to mounting evidence that exposure to air pollution—from traffic fumes to wood burners—increases the risk of developing dementia. Air pollution is one of the major modifiable risk factors for dementia, but individual efforts alone are insufficient.”
She stressed the importance of government leadership in addressing this issue, calling for a bold, cross-government approach to health prevention that involves coordinated actions across various departments, including those beyond health, to effectively tackle the drivers of dementia risk.
