According to a new study presented at the 2018 Scientific Sessions of the American Heart Association (AHA), chronic exposure to high noise can have serious consequences on the cardiovascular system, causing heart attacks or strokes.
The noise of machines on construction sites, the constant buzz of road traffic or the whirring of planes that land and take off ... These loud noise are not only harmful to hearing: when they are repeated, they can also have serious consequences for cardiovascular health.
This is highlighted by new work presented on November 5 at the 2018 Scientific Sessions of the American Heart Association (AHA), held in Dallas, Texas. According to their lead author, Dr. Azar Radfar, Ph.D., a researcher at Massachusetts General Hospital in Boston, repeated exposure to noise would increase the risk of stroke and heart attack because it would fuel the activity of the amygdala , a region of the brain involved in stress response.
The impact of the stress generated by the noise
To measure the consequences of chronic noise exposure on cardiovascular health, the researchers followed 499 participants with an average age of 56 and who, at the beginning of the study, had no cardiovascular disease or cancer.
The participants first underwent a PET scan, which allows a 3D measurement, as well as a scan of their brain and blood vessels. The researchers also examined the activity of the amygdala, a region of the brain that regulates stress and emotional response.
The science team then estimated the regular exposure of noise participants by comparing their home address with data from the United States Department of Transportation's National Transportation Noise Map, which includes information on levels of noise. noise from roads and air traffic.
Five years later, the researchers reviewed the participants' medical records for evidence of cardiovascular events. Of the 499 participants, 40 had had a heart attack or stroke in the last five years. The researchers also found that the participants most exposed to noise were also those whose stress-related brain activity was most noticeable. They also had more inflammation of the arteries.
A risk three times higher for stressed participants
How to explain that repeated noise has an impact on cardiovascular health? For the authors of the study, chronic and high noise pollution increases stress, which itself causes an increase in inflammation of the blood vessels. This is a known risk factor for cardiovascular disease.
The researchers also noted that participants with the most stress-related brain activity were more than three times likely to experience a major cardiovascular event, such as a heart attack or stroke. Even taking into account other risk factors, such as air pollution, smoking and diabetes, the team concluded that participants exposed to higher levels of noise pollution had an increased risk of events. cardiovascular.
"More and more research is revealing an association between environmental noise and cardiovascular disease, but the underlying physiological mechanisms have remained unclear," says Dr. Radfar. "We believe that our results offer an important insight into the biology behind this phenomenon."
For the scientist, the results of this work prove the need to count chronic exposure to noise as a risk factor for cardiovascular events. He concedes, however, that further research, in particular to determine whether reduced exposure to noise pollution can reduce the risk of heart disease.