A new study led by researchers at University College London (UCL) has found that prolonged exposure to high levels of air pollution may significantly damage the brain health of older adults living in England. Published in The Journals of Gerontology: Series A, the study links sustained exposure to nitrogen dioxide (NO₂) and delicate particulate matter (PM2.5) with declines in cognitive abilities, particularly in language skills. The findings suggest that the harmful effects of air pollution extend well beyond the heart and lungs, posing a serious threat to cognitive functioning as people age.
Nitrogen dioxide is primarily released into the atmosphere through the combustion of fossil fuels, with the chief sources being cars, buses, trucks, power stations, and various industrial machinery. Meanwhile, PM2.5, composed of microscopic particles, typically arises from burning petrol, diesel, oil, and wood. Due to their tiny size, PM2.5 particles can penetrate the lungs and enter the bloodstream, potentially causing widespread physiological damage, including the brain.
The researchers analysed data from 1,127 adults aged 65 and over who participated in the ELSA Harmonised Cognitive Assessment Protocol (ELSA-HCAP) 2018. They assessed participants’ exposure to air pollution over eight to ten years between 2008 and 2017. Cognitive performance was evaluated across several domains: memory, executive function (planning, decision-making, and problem-solving), language ability, and overall cognitive function. Participants underwent well-established neurocognitive tests, such as the East Boston Memory Test and the Wechsler Memory Scale, immediate and delayed recall tasks, backwards counting exercises, and shape drawing assessments.
The findings demonstrated that individuals living in areas with the highest NO₂ and PM2.5 pollution levels performed notably worse on cognitive tests than those with average pollution levels. The most striking association was in language skills, where individuals exposed to the highest pollution levels were disproportionately represented in the bottom third of test performance. This suggests a potentially specific vulnerability of language processing abilities to long-term environmental pollution.
The study further indicated that the source of air pollution matters. Pollutants from industrial activity, residential heating, and the combustion of fuels such as coal and oil were most strongly linked to impaired language performance. Although the researchers did not investigate the biological mechanisms underlying these findings, they propose that damage to the temporal lobe – a brain region essential for language processing and semantic fluency – may explain the observed cognitive effects. They emphasise the need for further research to understand better the neurological pathways through which pollutants exert their harmful influence.
Lead author Dr Giorgio Di Gessa (UCL Epidemiology & Health) commented: “Our study shows that air pollution is not just detrimental to respiratory and cardiovascular health, but also has profound implications for the brain, particularly with long-term exposure. The most consistent associations we observed were with language ability, hinting that some pollutants may selectively impair specific cognitive functions.” Echoing this call for action, Deputy Director of the ELSA study, Professor Paola Zaninotto, added: “By tracking pollution levels over a decade with high-quality data, we provide robust evidence that prolonged environmental exposure can inflict lasting damage on brain health.”
However, the researchers acknowledge certain limitations. The air pollution data covered only ten years, which may not fully represent a participant’s lifetime exposure. Additionally, annual averages were used, potentially missing the cognitive effects of short-term spikes in pollution. The relatively small, England-based sample also restricts the generalisability of the findings to other settings or larger populations. Nevertheless, the study offers compelling evidence for the urgent need to strengthen air quality regulations, particularly to protect the ageing population from preventable cognitive decline.
More information: Giorgio Di Gessa et al, Cognitive Performance and Long-term Exposure to Outdoor Air Pollution: Findings From the Harmonized Cognitive Assessment Protocol Substudy of the English Longitudinal Study of Ageing (ELSA-HCAP), The Journals of Gerontology Series A. DOI: 10.1093/gerona/glaf060
Journal information: The Journals of Gerontology Series A Provided by University College London
