Key brain structures in children growing up in poverty are connected differently compared to children in more affluent settings, according to a new study from Washington University in St. Louis.
In particular, the hippocampus — a brain structure linked to learning, memory, and regulation of stress — and the amygdala — linked to stress and emotion — connect to other areas of the brain differently in poor children than in kids from higher-income families.
The study, published in the American Journal of Psychiatry, analyzed the brain scans of 105 children ages seven to 12.
Using functional MRI scans, the researchers found that these connections were weaker, largely based on the degree of poverty to which a child was exposed. The poorer the family, the more likely the hippocampus and amygdala would connect to other brain structures in ways the researchers characterized as weaker.
“Our past research has shown that the brain’s anatomy can look different in poor children, with the size of the hippocampus and amygdala frequently altered in kids raised in poverty,” said first author Deanna M. Barch, Ph.D., chair of Washington University’s Department of Psychological & Brain Sciences in Arts & Sciences, and the Gregory B. Couch Professor of Psychiatry at the School of Medicine.
“In this study, we found that the way those structures connect with the rest of the brain changes in ways we would consider to be less helpful in regulating emotion and stress.”
Furthermore, these weaker connections were linked to a greater risk of clinical depression. Those in the study who were poor as preschoolers were more likely to be depressed at age nine or 10.
A previous study from the same research team had identified differences in the volume of gray matter and white matter, and the size and volume of the hippocampus and amygdala. But they also discovered that many of those changes could be overcome by nurturing parents.
That wasn’t found to be true, however, regarding changes in connectivity identified in the new study.
“Poverty is one of the most powerful predictors of poor developmental outcomes for children,” said co-investigator Joan L. Luby, M.D., the Samuel and Mae S. Ludwig Professor of Child Psychiatry and director of Washington University’s Early Emotional Development Program.
“Previously, we’ve seen that there may be ways to overcome some brain changes linked to poverty, but we didn’t see anything that reversed the negative changes in connectivity present in poor kids.”
The researchers measured poverty using what’s called an income-to-needs ratio that takes into account a family’s size and annual income. For example, the current federal poverty level is $24,250 for a family of four.
Children raised in poverty tend to have poorer cognitive and educational outcomes and are at higher risk for mental health problems, including depression and antisocial behaviors. Researchers hypothesize that factors such as stress, adverse environmental exposures (lead, cigarette smoke, poor nutrition, etc), along with limited educational opportunities, can contribute to problems later in life.
But Barch emphasizes that poverty doesn’t necessarily lock a child into a hard life.
“Many things can be done to foster brain development and positive emotional development,” she said.
“Poverty doesn’t put a child on a predetermined trajectory, but it behooves us to remember that adverse experiences early in life are influencing the development and function of the brain. And if we hope to intervene, we need to do it early so that we can help shift children onto the best possible developmental trajectories.”