Growing up poor is known to leave lasting impressions, from squashing IQ potential to increasing risks of depression. Now, as part of an effort to connect the dots between those outcomes and identify the developmental differences behind them, researchers have found that poverty actually seems to change the way the brain wires up.

Compared to kids in higher socioeconomic brackets, impoverished little ones were more likely to have altered functional connections between parts of the brain. Specifically, the changes affected the connections from areas involved in memory and stress responses to those linked to emotional control. The finding, appearing in The American Journal of Psychiatry, suggests that poor kids may have trouble regulating their own emotional responses, which may help explain poverty’s well-established link to depression and other negative mood disorders.

“My take-home message is that poverty gets under the skin,” lead author Deanna Barch, a psychologist and a neuroscientist at Washington University in St. Louis, told Ars. If people weren’t already energized to start addressing poverty and its myriad, deep-seated effects, this should be a fresh call to action, she said.

Barch and colleagues didn’t set out to study poverty, she said. But in the course of a 12-year study on the development of depression, she and her team realized they had the perfect opportunity to study how hardships mold the mind. With clinical and demographic data on 105 children collected since they were aged three to six, the researchers took a series of brain scans on the kids when they were between eight and 12 years old.

The scans allowed researchers to look at high-resolution structural and functional images of the brain. The functional images, which depict brain activity based on blood flow, provided a snapshot of brain activity at a resting state when the kids were asked to relax and stare at a plus sign on a screen.

Though the group of kids had a higher prevalence of depression and mood disorders than the general population of youngsters in the US, the group had a mix of low-, middle-, and high-income kids similar to that of the overall population’s blend. This allowed the researchers to examine if and how the kids’ brain structures and functions differed among the various socioeconomic groups.

In line with previous studies, the researchers found that two areas of the brain, the hippocampus and amygdala, tended to be smaller in poor kids. But, more strikingly, the way the activity of these two regions linked to the activity of other parts of the brain—the functional links—were also different. It's something that has never been reported before.

“The hippocampus is important for helping to regulate stress responses and for memory function, and the amygdala is really important for responding to salient events in the environment—both positive and negative,” Barch said. While data on the activity of those two regions alone is useful, Barch and her colleagues focused this activity connected with changes in other regions, particularly the prefrontal cortex. That’s the part of the brain that’s thought to be important for emotion regulation, cognitive control, and attention, she said.

Typically, we see negative correlations between activities in the hippocampus-amygdala regions and the prefrontal cortex—when one is worked up, the other is quiet. This suggests that the prefrontal cortex normally tones down the emotional responses brewing in the hippocampus and amygdala. But the poor kids tended to have less of that negative correlation. The authors suggest that this ultimately results in unbridled emotions, perhaps accompanied by depression and other mood disorders.

Whether the altered connections can be rewired with time or interventions is unknown, Barch said.

It’s important that the study uncovered this link between brain connectivity, poverty, and negative mood disorders, Natalie Hiromi Brito, a developmental neuroscientist at Columbia University Medical Center who was not involved with the study, told Ars. But she noted that the study was done in a group of kids with high levels of depression; it would be good to repeat it in a more representative sample of children to make sure the finding holds up.

Still, with 16 million US kids living at or below the poverty line, these types of studies are becoming more and more important, Brito added. “Studies like this underscore the importance of early intervention for positive emotional and cognitive development,” she said.

The American Journal of Psychiatry, 2015. DOI: 10.1176/appi.ajp.2015.15081014 (About DOIs).