Recent studies have linked prolonged exposure to air pollution to damage suffered by the brain that includes a decrease in its size, a higher risk for strokes and possibly dementia. The study was conducted by Beth Israel Deaconess Medical Center and Boston University School of Medicine. They have concluded that the effect of pollution on brain structure will affect cognitive function in middle-aged and old people.
The principle of the study was clear : they examined the brains of 943 patients using magnetic resonance imaging (MRI), then they analyzed the exposure of these patients to air pollution and then compared the direct effects that pollution has on the brain. All of the patients included in the study were older than 60, and among these the patients who were diagnosed with dementia or stoke were excluded.
Firstly, a decrease in brain volume was observed in people with prolonged exposure to polluted air. To be exact, they have linked an increase of 2 microgrames of fine-particle polluted matter per cubic meter with a reduction of the brain of 0.32%.
This 2 microgrames of fine particle polluted matter per cubic meter is a widespread value, associated with all the middle and large sized cities in the world. And it is the same amount that has been linked to a 46 % increase in a patient’s odds to get “silent strokes”. These are very small strokes that are asymptomatic, but can be identified on brain scans.
The importance of these silent strokes is that they are a risk factor in the onset of overt strokes. So an increase of 46 % in chances to get this condition” is concerning since we know that silent strokes increase the risk of overt strokes and of developing dementia, walking problems and depression.”, said Dr Sudha Seshadri, Professor of Neurology at the Boston University School of Medicine.
The study also clarified that the effect is exponential, meaning that exposure to a higher level of pollution will have even more extensive destructive effects. “On average participants who lived in more polluted areas had the brain volume of someone a year older than participants who lived in less polluted areas.”, pointed out Dr Sudha Seshadri.
While there is existing data that links air pollution to damage in children’s brains, this is the first study to be conducted on adult brains that researches the effects of air pollution, observed in terms of brain size and prevalence of strokes in these patients.
The exact mechanism of the modifications undergone by the brain structure has not been fully comprehended and this will be the aim of future studies. It is known that inflammation may cause the reduction of brain volume, and therefore the researchers suspect that polluted air may cause inflammation.
The study was published in the medical journal “Stroke” of the American Heart Association. “These results are an important step in helping us learn what is going on in the brain,” said researcher Elissa Wilker.
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