Study Finds Childhood Adversity Linked to Brain Differences in White, Black Children

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.

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.

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. ■

“Racial Disparities in Adversity During Childhood and the False Appearance of Race-Related Differences in Brain Structure”

“Understanding Social Determinants of Brain Health During Development”