The Impact of Racism on the Developing Brain

Growing up Black in the United States exposes children to an array of stressors that, among other things, negatively affect the developing brain. The influences are known as the “social determinants of health”—the “psychosocial” in the “biopsychosocial” model.

Everything not related to individual biology has been termed the “exposome” (i.e. after "genome"), defined by the CDC as “the measure of all the exposures of an individual in a lifetime and how those exposures relate to health. An individual’s exposure begins before birth and includes insults from environmental and occupational sources.”

People within economically disadvantaged locations—as expressed by “ADI” or “Area Deprivation Index”—are more likely to experience food insecurity, reduced access to housing and healthcare, lower birth weight, and long-term negative health outcomes (Kind et al., 2014). When people move to more advantaged zip codes, mental and physical health and subjective well-being improve over a 10- to 15-year period (Ludwig et al., 2012). The improvement is associated more with economic differences than race per se, highlighting the importance of material circumstance.

Racism and the Developing Brain

Research reported in the American Journal of Psychiatry (Dumornay et al, 2023) investigated how race-related disparity affects the developing brain. Authors further highlight how economic disadvantage and racial disparity go hand in hand. Compared with White households, Black households have higher rates of poverty, lower average income, lower educational attainment, and reduced employment. Children in such households have higher rates of adverse childhood experiences (ACEs), including trauma, domestic violence, divorce or parental separation, parental illness, death and incarceration, and they experience higher rates of neighborhood violence, alongside a host of other factors associated with structural racism and the aftermath of slavery.

Prior work has shown strong effects of adversity on brain structure and function—for example, post-traumatic stress disorder and other outcomes following abuse, trauma and neglect. The current research sought to expand on this work, isolating racism's impact on the developing brain.

Using data from the National Institutes of Health’s ABCD Study covering nearly 12,000 participants aged 9 and 10 from sites across the United States, researchers identified several thousand children from diverse ethnic groups with measures of 1) demographics, 2) ADI (Area Deprivation Index), 3) level of family conflict, 4) material hardship, 5) trauma history, and 6) structural MRI brain imaging looking at 14 regions of interest (ROIs) known to be affected by adversity.

The Developmental Neuroscience of Racism

Parental characteristics differed significantly among the groups. Compared with Black children’s parents, White children’s parents were three times more likely to be employed, nearly twice as likely to have a college degree, and made significantly more money. There was less conflict in White families, greater material support, less neighborhood deprivation and fewer traumatic experiences.

Gray matter volume (reflective of neuron cell density and health, as compared with white matter, the also-important wiring of the brain) was different for Black children in 11 of the 14 ROIs across the sample, prior to analyzing for specific racism effects. White children had significantly increased gray matter volume in the amygdala, hippocampus, frontal pole, superior frontal gyrus, rostral anterior cingulate, caudal middle frontal gyrus, and caudal anterior cingulate, and deceased volume in the pars triangularis.

When researchers analyzed the data for effects on gray matter unique to race, controlling for trauma and other forms of adversity, findings for several brain areas remained significant±— the caudal anterior cingulate, caudal middle frontal gyrus, lateral orbitofrontal gyrus, pars triangularis, pars orbitalis, superior frontal gyrus, and frontal pole.

Social and Individual Implications

Overall, Black children had unique differences in gray matter volume attributable to racism compared to White children, even after controlling for adversity. Lower gray matter volume was found in the amygdala, a brain region associated with threat and the experience of emotions more generally (including positive and negative emotions); in the hippocampus, involved with memory and contextualization of experience; and several subregions of the prefrontal cortex, related to conflict resolution and decision-making, reward and punishment, behavioral control, emotional expression, attention and mood regulation, social relations, working memory, long-term planning, and sense of self.

Study authors point out that their findings can be understood as the consequence of toxic physiological stress on the brain and body. Stress, whether baseline levels are chronically elevated or punctuated by acute insults, interferes with development by creating a survival-only orientation, burning resources that could be put toward more optimal development. A psychologically and physically safe and enriching environment, by contrast, supports development and leads to long-term health and well-being.

Future research will continue to identify the particular factors leading to racism-related changes in brain structure–including environmental exposures such as pollution-associated with high ADI locations. Recognizing that medical care is also hurt by such factors as race and ethnicity (as well as gender), future research will make sense of the complex systemic factors that undermine development.

In addition to structural imaging, functional brain imaging can elucidate how race affects everyday brain activity. For example, do external and/or internalized racism and other forms of trauma permanently shift how we see ourselves, reflected in default mode network activity; filter how we see the world and determine allocation of mental resources (e.g. what is considered important on a day-to-day basis), reflected in activity of salience networks; and affect decision-making, meaning-making, and overall self-regulation and governance, reflected in activity of executive or cognitive control networks?

The work has important implications for how to clinically approach racial trauma and helps policy makers identify the detrimental factors and direct change to where most immediately needed. While such research—even if "too little, too late" for far too long—may point out the obvious, the precision of neuroscience offers a powerful guide to prevention and intervention and can motivate policymakers.

The work also has implications for how to conceptualize the diagnosis and treatment of mental illness in populations with high-impact negative social determinants of health. It suggests that changes may be useful in clarifying to what extent psychiatric conditions are caused by exposomal versus individual factors.