- Exposure to air pollution is associated with cognitive impairment and an increased risk of depression.
- A recent study examined how air pollutants affect brain networks to mediate changes in cognitive function and boost the risk of depression.
- The findings suggest that genetic susceptibility to depression combined with high levels of exposure to air pollution has a disproportionate effect on brain networks involved in cognition and stress.
- Exposure to air pollutants has been associated with activation of brain networks that express genes associated with depression, suggesting that exposure to air pollution may cause adverse mental health effects by acting on the same brain networks related to genetic mechanisms of depression.
- This suggests that individuals with a genetic predisposition to depression may be more susceptible to the adverse effects of air pollution on mental health.
Besides its detrimental effect on physical health, prolonged exposure to air pollutants is also associated with harmful factors
Exposure to air pollutants, including fine particulate matter, may be associated with cognitive impairment and depression.
Microparticles, also known as PM2.5, are made up of small, respirable particles smaller than 2.5 microns. These particles usually come from industrial and vehicle sources.
How PM2.5 exposure may increase the risk of depression is not well understood.
Also, scientists do not know whether air pollution can interact with a genetic predisposition to depression to increase the likelihood of developing depression.
Individuals who have a genetic predisposition to a particular disease may have an increased likelihood of developing the condition in the presence of certain environmental factors or because of behaviors such as smoking.
A recent study investigated the effects of PM2.5 exposure, in association with a genetic predisposition to depression, on brain networks involved in cognition and social stress.
The study’s lead author, Dr. Hao Yang Tan, a scientist at the Lieber Institute in Baltimore, MD, said, Medical news today:
The study reveals for the first time how air pollution and genes interact with each other to influence important cognitive and emotional circuits in the brain. Air pollution alters the expression of depression-causing genes.”
“Previous studies have observed an association of air pollution with depression, but our findings are the first to show a direct neurological cause,” he explained.
“What is most interesting is that these two factors are linked in such a way that they have a multiplier effect on one’s risk of depression. This means that, together, dangerous genes and bad air increase the risk of depression much more than any of the two factors does in isolation.”
The study appears in the journal Proceedings of the National Academy of Sciences.
The study recruited 352 healthy participants residing in Beijing, China. Beijing has relatively high levels of air pollution, including high concentrations of PM2.5.
For each participant, the researchers studied several specific genetic variants associated with depression. From this information, they estimated their genetic susceptibility to depression.
To estimate PM2.5 exposure levels for each individual, the researchers used air monitoring data obtained from the city air quality monitoring station closest to each person’s home for 6 months prior to the study.
Depression is associated with cognitive deficits and higher levels of anxiety and depression. In other words, these individuals have an increased tendency to react anxiously or with depressive symptoms to a situation. Scientists assessed each participant’s anxiety and depression levels using a questionnaire.
The researchers first studied the effects of PM2.5 exposure on cognition and characteristics associated with depression.
They found that exposure to PM2.5 was associated with poorer performance on cognitive tests that include reasoning and problem solving. Higher anxiety and depression were also associated with PM2.5 exposure.
Next, the researchers examined the brain networks involved in cognition and information processing related to stress and its association with exposure to PM2.5 and genetic risk for depression.
The researchers measured the participants’ brain activity while performing a simple cognitive task using functional magnetic resonance imaging.
To assess the effect of social stress on brain activity during a cognitive task, researchers showed participants a picture of a competitor and compared their performance to that of the competitor.
Higher levels of PM2.5 exposure were associated with slower reaction times during the cognitive task, and this effect was amplified by PM2.5 exposure during social stress.
Social stress had a more pronounced effect on brain networks in individuals with a genetic predisposition to depression and greater exposure to PM2.5.
The effect of social stress on brain networks due to a combination of genetic risks and air pollution was greater than the sum of the effects from each individual factor. These findings suggest that air pollution may interact with the genetic risk of depression to affect brain networks.
The dorsolateral prefrontal cortex is a brain region involved in many processes, including cognition. One of the main areas whose connectivity changed during the cognitive task was in individuals with higher exposure to PM2.5 and a genetic predisposition to depression.
Remarkably, scientists have observed changes in the activity of the dorsolateral prefrontal cortex of healthy individuals with a genetic predisposition to depression and
To further study the interaction between genetic risk for depression and air pollution, researchers examined whether the combination of these factors differently affects the brain networks implicated in depression.
The researchers mapped the brain networks associated with depression by identifying areas of the brain that express high levels of depression-related genes.
The researchers used the online database Allen Brain Atlas, which provides detailed data on gene expression for brain regions. They then identified areas of the brain that showed associated expression of genes associated with depression.
The researchers examined whether this pattern of coexistence of depression-related genes in brain regions obtained using the atlas was similar to participants’ brain connectivity patterns during cognitive tests.
The coexistence pattern of depression-related genes derived using the atlas predicted brain connectivity patterns observed during the cognitive task. However, this was only the case for those who had a greater exposure to PM2.5 . levels And Higher genetic predisposition to depression.
The association was weaker in individuals with a lower genetic risk of depression or lower exposure to PM2.5.
This indicates that exposure to PM2.5 air pollutants affects brain network functions linked to genetic mechanisms of depression.
The researchers also conducted similar analyzes focused on the association between connectivity patterns of the dorsolateral prefrontal cortex with other brain regions and the coexistence of depression-related genes in these regions.
Co-expression of depression-related genes traces connectivity patterns to and from the dorsolateral prefrontal cortex in individuals at genetic risk for depression, high levels of exposure to PM2.5, or both.
Interestingly, the co-expressed genes that were associated with brain connectivity patterns in the prefrontal cortex included some genes involved in neuroinflammation.
“This is perhaps the first study to directly indicate how genes for brain disorders work in concert with each other and influence important cognitive and emotional functions in a living brain, and the effect of air pollution and genes in multiplying the effects of each on these brain functions,” said Dr. tan MNT.
“It’s now [in] Much less suspect that there are direct effects of air pollution on how genes in the brain function to influence the risk of these neuropsychiatric disorders.”
Dr Tan noted: “Individuals can limit their outdoor activities when pollution is high and be aware of their risks. Our study strongly suggests that individuals with genetic risk, for example, [a] Family history of brain disorders, may need extra caution and minimization [as much as] from the possibility of their exposure to any air pollution.”
“With this knowledge, leaders and public health officials around the world have ample evidence that additional controls on air pollution will lead to lower rates of depression—particularly in densely populated urban areas where air pollution is highest, and stress from social and economic inequalities and other forms of greater inequality.”
– Doctor. tan
Dr. Perry Sheffield, an environmental health researcher at the Icahn School of Medicine in Mount Sinai, New York, noted that this study “helps bring back the point that when we talk about vulnerable groups – I mean the groups of people who are most likely to experience negative health effects from a particular environmental exposure.” – We’re ultimately talking about all of us. Perhaps each of us is vulnerable in multiple ways, and our vulnerabilities change over the course of our lives.”
“Vulnerability can certainly be identified socially and unfairly – as we see driving racial and ethnic disparities in health – but it can be [also be] It is influenced by basic genetics, as we see here in relation to air pollution and depression, and certainly by life stage or age, “
“The value of clarifying these associations in a study like this is that it helps tell the story of why clean air, water, and the environment in general are so important to the health of people and communities.”
– Dr. Sheffield
Dr. Tan explained to MNT, “An important strength is that we have studied the effects of air pollution on the brain using the most direct measurements of live human brain function, magnetic resonance imaging techniques.”
We studied a large sample of individuals. We also removed many other factors that could have interfered with the study.” For example, their sample was “socially and economically homogeneous.”
“We also studied patterns of how depression risk genes work in concert with each other in postmortem human brains, and found that these patterns correlate well with how the living human brain functions, particularly in individuals at genetic risk for depression and at risk for depression. High air pollution” .
Dr Tan acknowledged there were some limitations to their approach, saying the team “only studied a limited set of genes for depression, and that’s probably just the tip of the iceberg.”
There are probably many other genes [for] Neuropsychiatric disorders implicated in the effect of air pollution on the brain. He concluded that understanding these matters more comprehensively will enable us to better identify those at risk, and possibly identify different drug routes or other ways to protect the vulnerable.