Air pollution increases the risk of dementia - In the spotlight

2023-04-28 12:33:38

28 avril 2023

A meta-analysis published in the BMJ highlights the links between exposure to fine particles and the risk of developing dementia. Explanations.

According to a meta-analysis recently published in the BMJ, fine particle pollution increases the risk of developing dementia. The Harvard TH Chan School of Public Health research team sifted through more than 2,000 studies: 51 of them, published in the past 10 years, linked air pollution and dementia. This meta-analysis notably includes a new tool to take into account the various biases that can influence the results of these studies.

The researchers were thus able to establish a link between PM2.5 particles and dementia, even for annual exposure below the standard of 12 micrograms per cubic meter of air (μg/m3), set by the United States Agency of protection. of the environment. In particular, for studies actively monitoring the data (via the fullest possible panel of sources), the researchers observed a 17% increase in the risk of developing dementia for each 2 μg/m3 increase in annual exposure. average to PM2.5.

As a reminder, PM2.5 particles are those whose diameter is less than 2.5 microns (μm). They “are emitted mainly during combustion phenomena or formed by chemical reactions from precursor gases present in the atmosphere”, explains the AirParif website.

40% of dementia cases linked to modifiable risk factors

Researchers from Harvard TH Chan School of Public health were also able to find links suggesting an association between dementia and nitrous oxide – 5% increased risk for every 10 μg/m3 increase in annual exposure – and nitrogen dioxide – 2% increase in risk for each 10 μg/m3 increase in annual exposure.

According to these data, the impact of air pollution on the risk of developing dementia is less than other known factors, such as education and smoking. However, given the huge number of people in the world exposed to air pollution, acting on this factor would have a significant impact on the health of the world’s population. “While exposure to PM2.5 and other air pollutants can be modified to some extent by personal behaviors, it is above all changes in regulations that will make the difference”, emphasizes Marc Weisskopf, director of the study.

Currently, worldwide, 57 million people are living with symptoms of dementia, the authors recall, a figure estimated at 153 million in 2050. Up to 40% of these cases are linked to potentially modifiable risk factors, such as exposure to air pollutants.

Source : Harvard T.H. Chan School of Public health, AirParif
Written by : Dorothée Duchemin – Edited by Charlotte David