Environmental pollution is well known to be toxic to our health. Its impact has been seen in a variety of conditions, from cancer to neurological disorders and respiratory problems.
The link between air pollution, particularly emissions from car exhaust, and an increased risk of dementia has been highlighted by a recent study that examined data from almost 30 million people.
Numerous studies have linked various air pollutants to dementia, with recent research identifying it as one of the contributing factors. However, significant differences exist in the quality of the evidence and the ability to establish a direct connection.
A prior study from over a decade ago revealed the links between pollution and autism and schizophrenia, where it explored the impact of pollution on brain inflammation.
- Advertisement -
Researchers from the University of Cambridge’s Medical Research Council (MRC) Epidemiology Unit conducted a systematic review and meta-analysis of existing literature to thoroughly examine this connection in a recent study that was published in The Lancet Planetary Health. By using this approach, they were able to synthesise research that, when taken into account independently, would not have enough weight or even yield contradictory findings, leading to more trustworthy, comprehensive conclusions.
The team examined 51 studies in all, most of which were from high-income countries and included data from over 29 million people who had been exposed to air pollution for at least a year.
The results demonstrated a distinct, statistically significant relationship between three categories of air pollution and dementia risk.
According to the review, an individual’s relative risk of getting dementia increased by 17% for every 10 micrograms per cubic meter (μg/m³) rise in PM2.5 exposure. In contrast, Central London’s roadside PM2.5 concentrations in 2023 averaged about 10 μg/m³.
The risk of dementia increased by 3% for every 10 μg/m³ increase in nitrogen dioxide (NO₂). In Central London, the average roadside NO₂ level measured in 2023 was 33 μg/m³.
A 13% increase in risk was associated with every 1 μg/m³ increase in fine particulate matter (PM2.5) in the form of soot. Roadside locations recorded yearly average soot concentrations of 0.93 μg/m³ in London, 1.51 μg/m³ in Birmingham, and 0.65 μg/m³ in Glasgow that same year.
Senior author Dr. Haneen Khreis from the MRC Epidemiology Unit says, “Epidemiological evidence plays a crucial role in allowing us to determine whether or not air pollution increases the risk of dementia and by how much. Our work provides further evidence to support the observation that long-term exposure to outdoor air pollution is a risk factor for the onset of dementia in previously healthy adults.
“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.”