Stress and the Architecture of the Brain

By Dorian Friedman

The body of animal research in the field seems to suggest that mild stress might be important for a human baby as well—conditioning her brain and hormone systems to respond appropriately to more serious threats that may arise. Betsy Lozoff, director of the Center for Human Growth and Development at the University of Michigan, explains, “We think it’s important that children fall down sometimes, or get minor illnesses once in a while. Being able to adapt and cope with stress is part of life, and you’d like to practice on small, manageable things.”

Undoing the Damage, Repairing the Architecture

If harmful conditions can weaken the developing brain’s sensitive architecture, can favorable ones strengthen it? Research suggests the answer is yes. Early in childhood, “the brain is plastic—or malleable—enough that if we provide different experiences we can change the developmental trajectory pretty dramatically,” says Levitt. And the same holds true for the stress-response system “thermostat,” which is most easily molded during the fetal and early childhood periods.

Hard evidence for this assertion comes, again, from animal studies. Remember those rat pups raised by different kinds of mothers? The ones reared by inattentive mothers were impaired in a number of ways, with intelligence, memory, and stress problems later in life. But when the same troubled pups were taken away from their inattentive mothers and placed in “enriched” settings in their first few weeks of life, their performance returned to normal. Brain researchers hypothesize that this quick reversal may result from an actual change in the brain’s chemistry—a shift that helps the rat’s brain find alternative pathways to reach the same level of performance and generate the right balance of neurochemicals. More to the point, findings like these suggest something else: That a nurturing, supportive environment may be the best protection a child can have against the harmful effects of stress in early life.

Research on this hypothesis is under way by several members of the National Scientific Council, and by many of their colleagues in the developmental sciences. Findings include compelling evidence relating to children reared in orphanages under terrible conditions, then later adopted into loving homes. The conclusion so far: Changing the conditions that cause the problem and providing enriching experiences as early as possible can compensate for a great deal of early stress and neglect—but it cannot reverse all of the stress-related brain effects. On this point, the science suggests that early impairments to the brain are indeed amenable to change because the brain can, in effect, “rewire” itself. But doing so takes longer than did the original wiring, and we do not know what is lost in the process.

Jack Shonkoff, chairman of the National Scientific Council for the Developing Child, director of the Center on the Developing Child at Harvard University, and Julius B. Richmond FAMRI Professor of Child Health and Development at the Harvard School of Public Health and Graduate School of Education, agrees. “To be sure, significant and prolonged stress can permanently change the brain’s circuitry,” he says. “But that’s different from saying these children are permanently doomed. Kids like these can still do well, but it’s likely to take more—and harder—work to help them do well. We’re either adding the burden of risk and vulnerability, or we’re giving them the best shot from the start. Obviously, it’s easier and less expensive to get things right the first time.”

Getting Things Right the First Time: Implications for Public Policy

Given what we now know and continue to learn about the costly consequences of stress on the brain architecture of the developing child, on families, and on society at large, the National Scientific Council’s scientists are guided by this simple motto: “It’s easier to get things right the first time.” (Or, scientifically speaking, “prevention is better than remediation.”) Toward that end, they point to a wide range of public policies and community investments—informed by developmental science—that are aimed at preventing or mitigating harmful sources of stress to developing children. In their ongoing conversations with policymakers, they highlight the following areas where current policy and the new scientific findings are at greatest variance:

• Starting before birth. Evidence demonstrates that developing fetuses and infants are especially vulnerable to many forms of environmental stress.

Investments to ensure early, consistent prenatal care are among the most cost-effective ways to promote the healthy development of young children. While the nation has made great strides in expanding access to good prenatal care, too many poor and minority women and pregnant teenagers still fall through the health-care cracks. In 2003, 25 percent of expectant African American and Hispanic women received no prenatal care in their first trimester of pregnancy, and minority women were twice as likely as white women to delay prenatal care until their third trimester—a very risky practice. And despite big drops in teen pregnancy, fully one-third of teenagers who do become pregnant still receive inadequate prenatal care—sharply increasing the odds their babies will be born at low birth weight and with serious health problems. Intensive efforts must target these women at greatest risk and others lacking health insurance.

• Confronting child abuse and neglect. Any sound prevention strategy also must focus on the threat of child abuse and neglect. “From a developmental perspective, there’s no such thing as a ‘mild’ case of child abuse or neglect,” says Nathan Fox, professor of Human Development and Psychology at the University of Maryland. By definition, abuse and neglect are “harmful and may have long-term consequences on the developing brain and behavior.” Science thus suggests the need for very new and different thinking about efforts to combat these problems.

For information about commonly used terms in Council publications, see Definitions.