Living In Poverty Can Impact Teenagers' Brain And Cause Depression, Study Says

A study by Duke University scientists shows how biology might cause depression experienced by high-risk adolescents whose family belongs to the socio-economically disadvantaged group in society.

Researchers analyzed chemical tags that influence the expression of a gene known as SLC6A4, changed as time pass. Basically, every gene has a set of instructions to code for specific proteins, or other cell products, however, the amount of protein a gene is able to produce can be changed by other genes and other processes. And since proteins are the workers of a cell, the number and type of proteins made will have a significant impact in cellular function and ultimately shape the organism itself.

"We focused on SLC6A4, which encodes the serotonin transporter, because we already know a good deal about the importance of this gene and this molecule on stress-related amygdala function and behavior," Dr. Ahmad Hariri, a professor of psychology and neuroscience at Duke, told Medical Daily in an email.

According to Science Daily, SLC6A4 is responsible for helping control the levels of serotonin though out the brain, including within the amygdala, an almond-sized region commonly believed to be the source of primary emotions. In a previous study, Dr. Hariri and his colleagues showed that the amygdala is becoming more active if there are threats, this happened to study participants when they saw aggressive-looking faces. Their brain scans showed the amygdala "lighting up" in response.

Building on this for the current study, Hamiri and his team focused on the process known as "methylation," which involves chemical tags to be attached to a stretch of DNA near the SLC6A4 gene. The more tags present, the less chances there is for this gene to be active and the less control it will have over the flow of serotonin, which is a mood regulator, in the brain.

For the study, Dr. Hariri and his team looked at a number of changes in these chemical tags in the brains of teenagers over time to fully understand how this can influence depression. There were a total of 132 non-Hispanic white teens who participated in the study coming from different households ranging from low to high socioeconomic status, and about half had a family history of depression.

At the beginning of the study, the teens were aged between 11 and 15 years old. As the study continued, the researchers collected information on the teens. The teens underwent brain scans as well as completed psychological assessments. The findings revealed that teens who grew up in poverty, had greater quantities of the chemical tags on SLC6A4 which is the gene linked with depression.

The tags altered genetic expression in such a way that the more tags, the more each teen's amygdala responded to aggressive faces (as seen during a brain scan). Importantly, teens with the most active amygdala were more likely to report symptoms of depression as they grew older. "This is some of the first research demonstrating that low socioeconomic status can lead to changes in the way genes are expressed," said Swartz. "And it maps this out through brain development to the future experience of depression symptoms."