A cocktail of many toxic components could be transported from the lungs to the brain via the bloodstream while breathing in polluted air– potentially contributing to brain disorders and neurological damage, a new study published in the Proceedings of the National Academy of Sciences has said.
Though it has been known that air pollution is significantly associated with an increased risk of hospital admissions for several neurological disorders, including Parkinson’s disease, Alzheimer’s disease, and other dementias, the scientists from the University of Birmingham and research institutions in China discovered a possible direct pathway used by various inhaled fine particles through blood circulation with indications that, once there, the particles stay longer in the brain than in other main metabolic organs.
The study conducted at the Emory University’s Rollins School of Public Health and Columbia University’s Mailman School of Public Health is the first nationwide analysis of the link between fine particulate (PM2.5) pollution and neurodegenerative diseases in the United States. The researchers leveraged an unparalleled amount of data compared to any previous study of air pollution and neurological disorders. The scientists revealed they had found various fine particles in human cerebrospinal fluids taken from patients who had experienced brain disorders – uncovering a process that may result in toxic particulate substances ending up in the brain.
Co-author Professor Iseult Lynch, from the University of Birmingham, commented: “There are gaps in our knowledge around the harmful effects of airborne fine particles on the central nervous system. This work sheds new light on the link between inhaling particles and how they subsequently move around the body.
“The data suggests that up to eight times the number of fine particles may reach the brain by travelling, via the bloodstream, from the lungs than pass directly via the nose - adding new evidence on the relationship between air pollution and detrimental effects of such particles on the brain.”
Air pollution is a cocktail of many toxic components, but particulate matter (PM, especially ambient fine particles such as PM2.5 and PM0.1), are the most concerning in terms of causing detrimental health effects. Ultrafine particles, in particular, are able to escape the body’s protective systems, including sentinel immune cells and biological barriers.
The team of scientists discovered that inhaled particles can enter the bloodstream after crossing the air-blood barrier - eventually reaching the brain, and leading to damage of the brain-blood barrier and surrounding tissues as they do so. Once in the brain, the particles were hard to clear and were retained for longer than in other organs.