Air pollution can reduce the volume of white matter in the brain and thus accelerate its aging, according to an American study published in the Annals of Neurology.
In recent years, there is more and more evidence that exposure to air pollution, especially particulate matter, has an impact on the risk of developing many diseases, including neurological ones. For example, exposure to particulate matter up to 2,5 micrometers in diameter (PM2,5), which is mainly formed during combustion processes, has been associated with a higher risk of stroke at relatively low exposure levels.
In addition, particle air pollution has been associated with multiple sclerosis (MS) relapses, as well as accelerated aging of the brain and deterioration of mental performance. Higher levels of substances, which are indicators of faster brain aging, were found in postmortem analysis of nerve tissue in children and young adults living in urban areas with higher air pollution.
The latest study by scientists from the University of Southern California in Los Angeles was carried out on a group of approximately 1400 women, ages 71 to 89, without symptoms of dementia. They were all participants in the study entitled Women’s Health Initiative Memory Study (WHIMS). On the basis of air quality monitoring data in their place of residence, it was assessed to what pollutants women were exposed to in the last 6-7 years. All of them underwent magnetic resonance imaging (MRI) of the brain. The analysis included, inter alia, lifestyle factors, socioeconomic status of senior women, and risk factors for cardiovascular disease.
The analysis showed that ladies who were exposed to inhalation of higher amounts of PM2,5 had a much smaller volume of white matter than their peers living in areas where the air was cleaner. White matter is made of nerve fibers that form long projections of neurons (so-called axons). Its role is to communicate different areas of the brain with each other, which ensures its smooth functioning.
Scientists calculated that when the overall exposure to PM2,5 increased by 3,49 micrograms per cubic meter, the decrease in white matter volume was similar to that in the brain that was 1-2 years older.
Changes in white matter were mainly observed in the frontal and temporal lobes and in the great commissure of the brain (also known as the corpus callosum).
“Studying the effects of air pollution on the human brain is a new area of environmental neurobiology,” comments lead author Dr. Jiu-Chiuan Chen. According to him, the latest study provides convincing evidence that many years of exposure to air pollution accelerate the aging of the brain and may contribute to reducing the volume of white matter. The researcher believes that further work is needed to assess exactly what mechanism is responsible for this.