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Paris (AFP) – According to a study published Wednesday, urban air pollution, mainly by vehicles, is associated with an increased risk of dementia.
The link remained even after the abuse of alcohol, smoking and other well-established dementia risk factors were ruled out, the researchers reported in the medical journal BMJ Open.
Globally, about 7% of people over the age of 65 suffer from Alzheimer 's disease or from a form of dementia, a percentage that reaches 40% above the age of 18. 85 years old.
The number of people affected worldwide is expected to almost triple by 2050, posing a huge challenge to health systems.
"Primary prevention of all dementias is a major public health problem in the coming decades," the researchers wrote.
Chemical substances released by pollution from exhaust pipes, such as nitrogen dioxide (NO2) and soot, are known to increase the risk of heart disease, stroke and problems respiratory, especially asthma.
But the fact that they also make it more likely Alzheimer's disease and other types of dementia remained unclear.
To learn more, a team of researchers led by Iain Carey of the Institute of Population Health at the University of London analyzed the medical records of 131,000 people living in Greater London and 50 to 79 years old.
None showed signs of dementia early in the study.
Based on residential addresses, scientists estimated the annual exposure to NO2 and fine particulate matter, known as PM2.5, and then tracked the health status of participants over a period of time. seven years.
During this period, nearly 2,200 patients, or 1.7% of the total, were diagnosed with dementia.
The fifth of these patients living in the most polluted areas was 40% more likely to be afflicted than the fifth in those areas where NO2 and PM2.5 were the fewest.
– Public health gains –
Since the study was based on an analysis after the fact rather than a clinical trial in an experimental setting, no definitive conclusion can be drawn as to cause and effect, the authors warned.
But the results strongly suggest that the chemical by-products of diesel combustion and gasoline can damage brain function.
"Circulation-related air pollution has been associated with lower cognitive development in young children," notes the study.
And even if the impact of air pollution remains relatively modest, they added, "the public health gains would be significant if it had appeared that the reduction of exposure could delay the progression of air pollution. Madness".
The study was well received by the experts who reviewed it before it was published.
"There is mounting evidence of the link between air pollution and brain health, including dementia and Alzheimer's disease," said Martie Van Tongeren, professor of occupational health and health. environment at the University of Manchester.
"That adds to that."
Kevin McConway of the Open University praised the study but noted that it only considered exposure to pollutants in the home and did not consider NO2 and PM2 levels. 5 at or near the workplace.
In September 2015, the US Environmental Protection Agency revealed that the German automaker VW had installed in its cars "defeat devices" to bypass emissions tests.
The European Environment Agency estimates that more than 400,000 people in urban areas of Europe die prematurely each year due to outdoor air pollution.
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