Exposure to air pollution, even at low doses, would be one of the main avoidable risk factors for cognitive decline. This is the result of a recent French cohort study, published in the scientific journal The Lancet Planetary Health. Results.
Air pollution and cognitive decline
It is now scientifically established that exposure to air pollution is a modifiable risk factor for cognitive decline. But what are the most dangerous air pollutants? At what dose? What cognitive functions do they act on? To answer these questions, French researchers analyzed data from the CONSTANCES cohort, made up of 220,000 adults, aged 18 to 69, randomly recruited.
Within this cohort, the scientists were particularly interested in a subset of 61,462 adults, aged 45 and over, who had performed cognitive tests to assess:
- Verbal episodic memory;
- Language skills;
- Execution functions.
To know ! Cognitive decline corresponds to an alteration of one or more cognitive functions, whatever the mechanism involved, its origin or its reversibility. Cognitive functions represent all the abilities that allow us to interact with our environment. They are what allow us to perceive, concentrate, acquire knowledge, reason, adapt and interact with others.
Variable effects depending on the pollutants
To assess the exposure of the cohort to air pollution, the researchers used readings taken of the atmospheric air around their geographic area of residence and took into account the most pollutants emitted by road traffic :
- Fine particles with a diameter of less than 2.5 micrometers (PM2.5);
- Nitrogen dioxide (NO2) concentration;
- Carbon sucks.
From all the data analyzed, the researchers demonstrated that exposure to black carbon and nitrogen dioxide was significantly associated with a decrease in cognitive abilities, in particular language fluency and executive functions. (necessary for planning, organizing or developing strategies, among others). The effect of pollutants occurs even at low exposure. But, the decline in cognitive performance is all the more important as the pollution is strong.
Reduce road traffic to preserve our cognitive functions
Also, the effect on cognitive performance depends on the air pollutant. For nitrogen dioxide and fine particles, the semantic fluency test is the most affected. Soot carbon appears to preferentially impact executive functions. Nevertheless, it remains to be elucidated what are the mechanisms that explain the action of pollutants on cognitive abilities. However, these data show that the main atmospheric pollutants alter, even at low doses, cognitive abilities, and this from the age of 45.
Thus, air pollution might thus accelerate age-related cognitive decline and promote the occurrence of pathologies such as Alzheimer’s disease. These diseases might become more frequent, with an earlier age of onset. The results of this study support policies to reduce emissions of atmospheric pollutants, intended to preserve the environment, but also to protect our health!
Estelle B., Doctor of Pharmacy
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