Genetic predisposition to depression combined with exposure to air pollution “enormously” increases the risk of healthy people suffering from the disorder, according to a study published in PNAS.
“The conclusion of this study is that air pollution not only affects climate change, but also affects the functioning of the brain,” according to Daniel Weinberger, co-author of the study and member of the Lieber Institute (USA), which conducted research together with Peking University.
Air pollution affects important cognitive and emotional circuits in the brain by changing the expression of genes, something that “has not been shown before,” increasing the risk of depression, said Hao Yang Tan, project leader.
The expert indicated that more people in areas of high contamination will be depressed because “their genes and the contamination of their environment exaggerate the individual effects of each one.”
All people have a certain propensity to develop depression, but some have a higher risk inscribed in their genes, which does not mean that they have to suffer from it, but it raises the risk above the average for the population.
The study, according to its authors, shows that it is much more likely that depression develops in otherwise healthy people who have these key genes and who live in environments with high levels of airborne particles.
The brain circuits involved in the effects of genetic risk and air pollution control a wide range of important functions of reasoning, problem solving and emotional suggesting potentially widespread brain effects of air pollution.
A global association that synthesized scientific data on air pollution, neuroimaging, brain gene expression and other additional data collected by a genetic consortium from more than 40 countries participated in the research.
For the investigation, 352 healthy adults who lived in Beijing, a city with well-documented daily pollution levels.
Participants underwent a genotype test, collected information on their exposure to contamination during the previous six months, and performed a series of simple cognitive tests. At the same time, they had an MRI that showed which parts of the brain were activated during cognitive processing.
To directly examine the functioning of depression genes in the brain, the team examined data from a genetic atlas of post-mortem human brain tissue. In this way, they compared brain networks with those of living subjects to see if these genes are the cause of the effects of air pollution.
The team found that people who had a high genetic risk for depression and high exposure to the particles had brain function marked by greater integration with the way depression genes work together.
The researchers also found that a subset of genes that drove these associations was involved in the inflammation a finding that could provide new pharmacological insights to mitigate the effects of air pollution on brain function and depression.