What doesn’t kill you makes you stronger? Not always. For kids growing up in chronically stressful environments—think children living in poor housing conditions, frequently witnessing domestic violence, or suffering abuse or neglect—the experience can get under their skin and affect their behavior for a lifetime.
In the just-released issue of the Future of Children, Ross Thompson outlines the growing body of research on the neurobiological effects of chronic stress during early childhood and what it means for behavior. Since chronic stress is especially prevalent in low-income homes, we must think of neurobiology as another pathway by which disadvantage is passed from generation to generation.
How is neurobiology and behavior affected by chronic stress in early childhood?
Early experiences, even beginning in utero, signal what type of environment the individual will face, and the brain and other biological systems develop accordingly. Especially important is the hypothalamic-pituitary-adrenocortical (HPA) axis, the system that responds to threat by producing the hormone cortisol to arouse vigilance, self-defense, and emotion.
Repeated exposure to stress can alter the functioning of this axis over time, which means children who experience chronic stress often struggle to regulate their emotions, pay attention, and control their impulses. Alternatively, chronic stress can lead some children to show a shutting down of their stress system, so that they inadequately react to stress.
Additionally, constant production of stress hormones like cortisol can affect development of the prefrontal cortex (important for self-regulation), the hypothalamus (for emotion), and the hippocampus (for memory).
In short, the “wiring” of children’s biological systems to help them survive in a threatening environment hurts them in the classroom and most social scenarios.
Why does this matter for intergenerational social mobility?
Children who struggle with attention and impulse control—what many call non-cognitive skills or character strengths—are less likely to succeed in the classroom and labor market, as the Character and Opportunity project at Brookings is currently exploring. This is an intergenerational mobility problem because the chronic stress that limits the development of these strengths is most often found in homes at the bottom of the income distribution.
What can we do about it?
There is something that can soften the link between chronic stress and harmful neurobiological development: warm, responsive, and consistent caregiving. Children whose foster parents were taught to be more affectionate and better interpret and respond to infant signals showed more typical HPA activity and more moderate cortisol reactivity when faced with a threat. As with many other pathways of disadvantage, to help the child, we need to help the parents.