Study Finds Childhood Adversity Linked to Brain Differences in White, Black Children
Abstract
Unlike its cousin, bipolar I disorder, which has been extensively studied and depicted in popular literature and on screen, bipolar II disorder is poorly understood, underdiagnosed, and insufficiently treated. This has often resulted in an over 10-year delay in diagnosis.
The history of psychiatry and neuroscience is stained with attempts to scientifically prove the fallacy that there are inherent differences between the brains of Black and White people.
“Children absorb more than we think they do,” says Walter E. Wilson Jr., M.D., M.H.A. “We often like to think that 9- or 10-year-olds aren’t especially aware of their surroundings or that when adults have problems, the children don’t have to worry. But this study proves that kids are absorbing their environments and the things their parents deal with, like paying rent or getting food on the table, have a major developmental impact on children.”
“Physicians and scientists tried to demonstrate that African Americans were inferior to justify discrimination and systemic racism,” said Walter E. Wilson Jr., M.D., M.H.A., chair of APA’s Council on Minority Mental Health and Health Disparities. “Challenging that narrative with data is incredibly important. We need to rewrite that unfair history.”
A study published in February in The American Journal of Psychiatry offers important new insights into the false appearance of race-related differences in brain structure between Black and White children. The study found that childhood adversity, which Black children are more likely to experience, may result in lower brain matter volume in regions that are important for regulating the emotional response to threat.
“We need to appreciate that when we’re talking about how experiences impact the brain, we’re not talking equally about different groups,” says Nathaniel Harnett, Ph.D. “If we really want to find equitable, generalizable markers of psychiatric disease, it’s important to dive into the details of what’s really happening with our participants.”
“What the data show is the overwhelming impact of structural racism on the developing brain, which is going to have big implications for these kids’ emotional health as they start to get older, especially if we don’t address the different aspects of structural inequities and racism,” said one of the study’s authors, Nathaniel Harnett, Ph.D. He is the director of the Neurobiology of Affective Traumatic Experiences Laboratory at McLean Hospital and an assistant professor in psychiatry at Harvard Medical School.
The research team used data from the study published in February in Adolescent Brain and Cognitive Development (ABCD) Study released in March 2019, which included 9,382 participants aged 9 and 10. They gathered family demographic data through surveys that the participants’ parents completed. The surveys assessed both parent and child race/ethnicity; parental education and employment; parental hardship (such as not being able to afford rent); and total family income, among other variables.
The participants’ neighborhood disadvantage was assessed using the Area Deprivation Index, which uses 17 socioeconomic indicators, including poverty, housing, and employment, to characterize a given neighborhood. Family conflict was assessed using the Youth Family Environment Scale, and trauma history was assessed using the Schedule for Affective Disorders and Schizophrenia for School-Age Children for DSM-5. The authors used structural MRI data to investigate the relationship between racial disparities in adversity exposure and differences in brain structure.
Study Found Large Differences in Experiences With Adversity
The authors found that White children’s parents were more likely to be employed, have higher educational attainment, and greater family income compared with Black children’s parents (88.1% of White parents made $35,000 a year or more versus 46.7% of Black parents). White children also experienced less family conflict, less material hardship, less neighborhood disadvantage, and fewer traumatic events compared with Black children.
There were also important differences between Black and White children in their gray matter volume. White children showed greater gray matter volume compared with Black children in 10 brain regions. But Harnett emphasized that, overall, these differences were small.
“What we’re seeing is the history of these individuals; the racialized nature of that; and the way we construct our society to overburden certain groups with these disparate experiences, which really contribute to these differences.”
Harnett and his colleagues found that childhood adversity was associated with lower gray matter volume in the amygdala and several regions of the prefrontal cortex. Black children showed lower gray matter volumes in the amygdala, the hippocampus, and several subregions of the prefrontal cortex compared with White children. These regions of the brain are key to regulating the emotional response to threat, Harnett explained.
Differences in exposure to adversity accounted for many, though not all, of the differences in gray matter that the research team identified. He noted that there are numerous adversities that Black children are more likely to experience that were not measured by the ABCD study, which could account for the additional differences in gray matter volume. Additionally, the study did not look into positive factors that could impact brain structure, Harnett said.
Study Provides Deeper Context to Understand Youth
In an accompanying commentary, Deanna Barch, Ph.D., and Joan Luby, M.D., pointed to some of the additional adverse social determinants of health that were not examined in the study, such as a youth’s personal experience of racism. They wrote that some people have argued that the experience of racism is a form of trauma itself that can lead to posttraumatic stress disorder. Barch is the Gregory B. Couch Professor of Psychiatry and chair of the Department of Psychological & Brain Sciences at Washington University School of Medicine in St. Louis. Luby is the Samuel and Mae S. Ludwig Professor of Psychiatry and director and founder of the Early Emotional Development Program at Washington University School of Medicine in St. Louis. The study “is an important step towards understanding how [social determinants of health] impact brain development in youth as a potential pathway to risk for mental health challenges,” Barch and Luby wrote.
Key Points
Black children are far more likely to experience adversity compared with White children. Nathalie Dumornay, B.S., Lauren A.M. Lebois, Ph.D., Kerry J. Ressler, M.D., Ph.D., and Nathaniel Harnett, Ph.D., investigated how adverse experiences impact the brain. Among the findings:
The parents or caregivers of Black children were more likely than those of White children to be unemployed, have lower educational attainment, and have lower incomes.
Childhood adversity was associated with lower gray matter volume in the amygdala and several regions of the prefrontal cortex.
Adversity contributes to slight differences in gray matter volume between Black and White children in key regions of the brain associated with regulating the emotional response to threat.
Bottom Line: Experts say this study emphasizes the need to address systemic inequities and to support Black children and their families.
Wilson, a child and adolescent psychiatrist, said the study provides a deeper context for better understanding youth, especially those from disadvantaged backgrounds. “When we have youth in our offices who have been exposed to many of the adversities included in this study, we need to understand the stressors they have been through and remember how it may impact their brain development,” he said.
The study should also be an important reminder that patients are intimately impacted by the environments in which they grew up, Wilson said. When youth are having trouble regulating their emotions, psychiatrists should investigate what resources the families or the communities need.
“Children are vulnerable, and they are at the mercy of larger community and societal problems that are out of their control, but that trickle down to them,” he said. “A child does not need to be fixed; the communities need to be fixed.”
Harnett hypothesized that the brain differences identified in the study may only accelerate as the children become adults. “That is a terrifying proposition,” he said, and it impacts the psychiatric care they might need. “Some individuals who are from racialized backgrounds are constantly exposed to threatening situations as a result of individual and structural racism,” he continued. “How do we work with them to address that? Those threats aren’t going away. They experience constant pressure to be vigilant and ready to respond to very real potential threats. How do we conceptualize classical approaches to treating psychiatric disorders with these individuals’ experiences in mind?”
The study was supported by grants from the National Institute of Mental Health. ■
