British scientists are about to launch a remarkable research project that will show how the air we breathe can affect our brains. They say this work will be crucial for understanding a major medical problem: how air pollution can cause dementia.
In recent years, scientists have discovered that air pollution is one of the most pernicious threats to human health and have shown that air pollution is implicated in causing cancer, heart disease, diabetes, low birth rates and many health problems.
Now scientists of the Francis Crick Institute will look at its involvement in the phenomenon of neurodegeneration through a research project, entitled Rapid, which is funded by the charity Race Against Dementia and will launch tomorrow.
At Rapid, scientists will investigate the exact processes by which small pollutant particles can lead to dementia; work that could provide insight into how air particles cause disease in general and could also help develop new drugs to halt the progression of conditions such as Alzheimer’s disease.
“Air pollution is generally not associated with dementia. However, epidemiologists have recently discovered that airborne particles are actually quite strongly associated with the risk of neurodegenerative diseases,” said one of the project leaders, Prof. Charles Swanton, Deputy Clinical Director of the Crick. “We want to discover exactly how small particles in the air can have such profound effects on our brains and use that knowledge to develop new drugs to treat dementia.”
An important type of air pollution consists of suspensions of tiny fragments of solids and liquid droplets. These are produced from car and truck exhaust, factories, dust, pollen, volcanoes, forest fires and other sources and are known as particulate matter 2.5 or simply PM2.5.
These particles have a diameter of less than 2.5 millionths of a meter – about 30 times finer than a human hair – and are so small that they can penetrate deep into the recesses of the human body. In the case of dementia, PM2.5 particles are inhaled. They are believed to enter the brain through the olfactory bulb, a round mass of tissue located above the nasal cavity that plays a key role in processing odor information.
“In the brain, PM2.5s appear to be taken up by immune cells in the central nervous system and in their wake we think neurodegeneration may occur,” Swanton said.
However, exactly how this process unfolds and leads to dementia is not clear, and a key goal of the Rapid project will be to reveal the precise process by which PM2.5s cause brain tissue to form the clumps that characterize are from Alzheimer’s disease. .
“We have good evidence linking exposure to PM2.5 particles to brain diseases such as Alzheimer’s and Parkinson’s, but we don’t yet know whether these actually cause neurodegeneration directly or whether they drive the process that is already taking place in vulnerable individuals. says Sonia Gandhi, head of the Neurodegeneration Biology Laboratory at Crick and University College London.
Researchers at the Crick believe that one of three different mechanisms is involved in how air pollution causes dementia. PM2.5 particles can directly accelerate the process by which proteins clump together in the brain – causing Alzheimer’s disease.
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Alternatively, it could be that the arrival of particles disrupts the brain’s ability to clear clots. In other words, the PM2.5s disrupt the body’s cell-clearance system and make it harder to remove other proteins that cause diseases like Alzheimer’s.
Third, it has been suggested that PM2.5s are picked up by the brain’s immune cells called microglia and could cause these cells to trigger inflammation that triggers the onset of dementia.
The research into which mechanism is involved in the development of dementia will focus on in vitro experiments with human stem cells and on animal models.
“Once we understand these mechanisms in more detail, we can use that knowledge to develop treatments that will dampen the impact of air pollutants and perhaps one day prevent the environment’s effect on brain diseases,” Gandhi said.