Many of us are aware that pollution can have detrimental effects on our health, specifically in relation to respiratory and cardiovascular issues. Studies have shown that living in an area of bad air quality significantly raises our risk of developing heart disease, having a stroke, and being affected by breathing problems.
In fact, when the World Health Organization delved into the issue of air pollution in 2016, they found that 92% of the world’s population breathes unhealthy air — a definite sign that air pollution is quite a significant threat to global public health. Their comprehensive analysis also found that approximately three million deaths a year were linked to outdoor air pollution. Most of these deaths were related to cardiovascular, pulmonary, and other noncommunicable diseases.
It is easy to understand how air pollution might contribute to these illnesses. It turns out, however, that poor air quality might be responsible for causing additional problems, including cognitive decline. An August 2018 study conducted by scientists in China suggests just that, in addition to respiratory and cardiovascular issues, air pollution was also causing significant cognitive decline.
The study reviewed math and verbal scores from 31,000 Chinese citizens and this data was then matched with air quality data from 2010 to 2014. The researchers found cognitive decline in the test scores in areas where pollution was severe. This remained true even when the data was controlled for cognitive decline due to aging. The scientists also found that long-term exposure to particulate matter, sulfur dioxide, and nitrogen dioxide led to cognitive declines in study participants. Less-educated men seemed to suffer the greatest impact and had low verbal and math test scores.
How is it that the air we breathe impacts our brains? Scientists are still trying to figure this out and more research is needed to understand exactly what is happening. Some studies have shown that children and young adults who were regularly exposed to poor air quality had evidence of inflamed brain tissue, altered immune responses, and abnormalities in the function of the endothelial cells that make up the BBB (blood-brain-barrier). Xin Zhang, one of the authors of the study conducted in China, says:
“We speculate that air pollution probably puts greater damage on the white matter in the brain, which is associated with language ability.”
It’s interesting to note that research has shown that women have more white matter brain tissue than men and perhaps this is why the study conducted in China showed more of a negative impact on men than women.
Environmental toxicologist Dan Costa explains that the human body’s internal makeup is highly interconnected. Air pollution has been shown to impact not just the lungs, but the heart, brain, and reproductive system. He says:
“When something comes in [to the body] that’s potentially toxic, it’s implications are everywhere.”
Dr. Costa suspects that pollutants reach the brain via the blood stream. He believes this triggers the immune system thereby causing inflammation. Over time, too many toxic particles could cause too much inflammation, which may accelerate how quickly the brain ages.
Many of us have often thought of the brain as somewhat of a protected organ, perhaps relatively immune to various environmental dangers. Unfortunately, recent research has shown this is not necessarily the case, and hopefully as research into the brain continues to expand, some answers, and solutions, can be found.