Exposure to air pollutants has been identified as a potential target for risk reduction at the policy level, as outlined in the recently updated report from the Lancet Commission on Dementia Prevention, Intervention, and Care. In recent years, the body of research on environmental risk factors for dementia, such as exposure to air and noise pollution, has expanded, urging policymakers to prioritise public health initiatives to reduce these exposures and to implement stricter environmental regulations. A newly published epidemiological study, led by doctoral student Jens Soeterboek from Maastricht University (Netherlands), investigated the relationship between ambient air pollution and cognitive functioning as well as brain volume.
The researchers used data from more than 4,000 participants of the Maastricht study, an observational study of residents in the South of the Netherlands, and matched it to postcode-level air pollution exposure data. Specifically, they assessed exposure to particulate matter smaller than 2.5 μm and 10 μm (e.g., as emitted by traffic, livestock stables, industry, and wood burning), nitrogen dioxide (e.g., mostly emitted by traffic and industry), and soot (e.g., as emitted by wood burning, industry and traffic). Cognitive functioning was evaluated using neuropsychological tests of memory, executive function, and attention. They also underwent structural MRI scans. The study found no association between the level of exposure to these pollutants and cognitive function. However, participants exposed to higher levels of particulate matter smaller than 2.5 μm showed a higher degree of brain atrophy on average. “These particularly small particles can enter the bloodstream, affecting the circulatory system and potentially causing systemic inflammation, which can impact brain integrity," Jens Soeterboek explains.
The associations were independent of age, sex, lifestyle, socioeconomic status, and the degree of urbanisation - the population density in a given area. "Our findings suggest that exposure to small particulate matter within mid to high ranges, within our specific sample, may be associated with brain morphology," he explains. While some studies have linked elevated levels of neuroinflammation and proteins associated with Alzheimer’s disease to air pollution exposure, further investigation into potential underlying mechanisms is needed. The study was published open access in the journal Environment International and can be read here:
https://www.sciencedirect.com/science/article/pii/S0160412024006342?via%3Dihub