Stark and rising socioeconomic inequalities plague many countries, including the United States, and politicians, economists, and—fortunately—scientists, are debating its causes and solutions. But the effects of inequality’s may go beyond simple access to opportunity: a new study finds that socioeconomic disadvantage can actually induce permanent changes in brain connectivity that put poor children at higher risk of mental health problems, particularly depression. The findings could have important policy implications and provide new arguments for expanding anti-poverty interventions, researchers say.
For the study, researchers at the Washington University School of Medicine in St. Louis, MO, analyzed brain scans of 105 children ages 7 to 12, finding that two key structures in the brain are connected differently in poor children than in kids raised in more affluent settings. Specifically, the brain’s hippocampus — a structure that plays a critical role in learning, memory and stress regulation — and the amygdala — which is linked to stress and emotion — connected to other areas of the brain differently in poor children than in kids whose families had higher incomes.
Those connections, viewed using functional MRI scans, varied depending on the degree of poverty to which a child was exposed — a phenomenon known as a “dose-response relationship”. The poorer the family, the more likely the hippocampus and amygdala would connect to other brain structures in ways the researchers characterized as weaker. In addition, poorer preschoolers were much more likely than their more affluent peers to have symptoms of clinical depression when they reached school age.
The findings were published online ahead of print in The American Journal of Psychiatry.
“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, PhD, 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.”
Those changes in connectivity also increase the risk of developing mood disorders, particularly clinical depression. Those in the study who were poor as preschoolers were more likely to be depressed at age 9 or 10, even if they were no longer living in poverty.
Functional MRI scans show areas in the brains of poor children with normal connectivity highlighted in red and blue, and weakened connectivity shown in green. The areas in green are among several areas — detailed in other brain scans — where connections are weakened in children raised in poverty. (Image: Washington University School of Medicine)
Previous research from the same team identified differences in the volume of gray matter and white matter, and the size and volume of the hippocampus and amygdala. But they also found that many of those changes could be overcome through nurturing from parents. That wasn’t true, however, regarding the 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, MD, 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. The current federal poverty level is $24,250 for a family of four.
According to a recent report from UNICEF, the U.S. has one of the highest rates of childhood poverty in the developed world, despite being one of the richest nations on earth. The National Center for Children in Poverty estimates that more than 16 million U.S. children live in families with incomes below the federal poverty level, and for the first time in modern history, more than half of U.S. public school students live in low-income households.
Children raised in poverty tend to have poorer cognitive and educational outcomes and are at higher risk for psychiatric illnesses, including depression and antisocial behaviors. Researchers hypothesize that factors such as stress, adverse environmental exposures — including lead, air pollution and poor nutrition — along with limited educational opportunities, can contribute to problems later in life. This new research adds to a growing line of evidence showing that poverty can also embed itself in children’s brains, causing structural and functional changes that make it harder to deal with the stress that comes along with socioeconomic disadvantage.
However, Barch emphasized that the link between poverty and poor outcomes doesn’t necessarily lock a child into a difficult 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.”
These findings underscore the importance of expanding social programs that reduce the burden of poverty and, subsequently, the negative life outcomes it can produce. According to the Children’s Defense Fund (CDF), increasing investments in existing policies and programs that work could reduce overall child poverty 60 percent, Black child poverty 72 percent, and improve economic circumstances for 97 percent of poor children at a cost of $77.2 billion a year — the equivalent of 2 percent of the national budget, or six times less than the annual societal cost of poverty ($500 billion).
Unfortunately, some of the most effective anti-poverty programs in existence — like food stamps, subsidized school lunches, Medicaid, and the Children’s Health Insurance Program (CHIP) — are under attack by Congressional Republicans, who are pushing to authorize devastating cuts to these essential lifelines under the guise of budgetary constraints. However, as the CDF points out, the problem is not that we don’t have the money to fund such initiatives; the problem is that we choose not to spend it on our nation’s children.
Reducing child poverty “is about values and political will,” the CDF states. “Sadly, politics too often trumps good policy and moral decency and responsibility to the next generation and the nation’s future. It is way past time for a critical mass of Americans to confront the hypocrisy of America’s pretension to be a fair playing field while almost 16 million children languish in poverty.”