Worldwide, 9 in every 10 people breathe highly polluted air. A known contributing factor for many respiratory illnesses such as lung cancer, an increasing body of research is now suggesting that it may also contribute to cognitive decline, such as that seen in Alzheimer’s.
In new research published in academic journal, Brain, researchers from the University of Southern California in Los Angeles found a correlation between poor air quality and cognitive function impairments. They analyzed data from 998 women aged between 73 and 87; each woman undergoing two brain scans, five years apart. Using a machine learning model trained with brains from people with Alzheimer’s disease, the investigators then gave each brain scan a cognitive decline score.
They then compared this data with information on where each woman lived alongside information on air pollution in those areas. This way, they were able to understand each woman’s degree of exposure to fine particle pollution, tiny pollutants that are excreted from traffic exhaust fumes and smoke, and how this related to their cognitive function.
After putting the two data points together, the researchers found a clear correlation between the amount of fine particle pollution in a given area and the women’s declining cognitive abilities. Although they were not able to find a direct causation between air quality and the onset of Alzheimer’s, they found that those more exposed to fine particle pollution tended to display greater decline in immediate recall and new learning. The correlation even remained after the researchers adjusted the results for lifestyle factors such as income, smoking status and level of education.
According to the study’s co-author, Andrew Pektus, "This is the first study to really show, in a statistical model, that air pollution was associated with changes in people's brains and that those changes were then connected with declines in memory performance.”
He continued, “Our hope is that by better understanding the underlying brain changes caused by air pollution, researchers will be able to develop interventions to help people with or at risk (of) cognitive decline.”