Stress and your child's brain
New research suggests that children are affected by stress in surprising ways.
By Hank Pellissier
Stress! Bad for the body! Bad for the brain! We've seen the articles, watched the 11 o'clock news reports on the "silent killer," and complained to friends and family about how stressed-out we are. While we all know that adult stress can lead to serious illnesses such as ulcers and hypertension, we don't associate these maladies with children.
But research suggests that chronically stressed children do pay a heavy price. In fact, they are at risk of cognitive damage, because their brains are not yet fully developed.
A host of statistics suggest that American children are indeed experiencing stress at new levels: suicides among adolescents have quadrupled since the 1950s; only 36 percent of 7th graders agreed with the statement “I am happy with my life;” and in the past decade, using pharmaceuticals to treat emotional disorders has shot up 68 percent for girls, 30 percent for boys.
An ancient response to new problems
To get a sense of just what children are up against, it's useful to understand the physiological effects of stress on the brain.
When a child experiences stress, the hypothalamus (above the brain stem) releases a hormone that rushes to the neighboring pituitary gland. The pituitary gland then mobilizes the production of a second hormone that swims via the bloodstream to adrenal glands above the kidneys. The adrenal glands activate adrenaline and cortisol. Adrenaline accelerates the child's heart rate and elevates the blood pressure. Cortisol pumps up the blood sugar level, elevating the child's muscle and memory power and boosting the pain threshold.
So what's wrong with that, you wonder? Between increased memory power and elevated pain threshold, wouldn't this help children learn faster and better? Far from it. Our fight-or-flight stress reaction is designed for emergency life-or-death situations. Eons ago, the physiological response to stress allowed us to escape (or battle) Paleolithic beasts, enabling us to prevail against dangers that lasted about thirty seconds.
Unfortunately, modern problems and challenges — perfectly exemplified by the 13 years of schooling expected of each child in our nation — aren't untangled as swiftly. They require long-term focus and fortitude — the very thing that stress can undermine.
Is your child caught in the rat race?
What happens when the brain is stressed — not for a few seconds, but year after year? Stress hormones end up swamping our bodies for days, weeks, months. Research shows that cortisol, specifically, chews up the brain if it loiters there long-term. When lab rats in Israel, Germany, USA, China, and Italy were given daily injections of rat cortisol for several weeks, it killed brain cells in their hippocampus region, leaving them depressed, anxious, fearful, immature, needy, and unable to learn new behaviors (e.g. stuck in the same old "rat race)."
Chronic stress takes its toll on the brain in other ways as well.
In Why Zebras Don't Get Ulcers, Robert M. Sapolsky, a Stanford University professor of psychology, enumerated the many ways that brain functions break down when subjected to chronic stress: "Hippocampal neurons no longer work as well," "neural networks get disconnected," "the birth of new neurons is inhibited," and "hippocampal neurons become endangered." Translation: brains under chronic stress will have trouble learning new things and committing new material to memory.
In a 2006 study, researchers at Arizona State University noted that long-term stress withered the dendrites (neuron branches) in the hippocampus, and decreased dendrite length and branch numbers. Dendrites provide the avenue along which new learning takes place and hippocampus injury (central to memory functioning) leads directly to learning impairment.
None of this is good for the adult brain, but children's fast-developing brains with dendrites numbering in the millions are especially vulnerable to ravages of cortisol. Study after study has found that children who are exposed to extremely stressful situations — via violence in the home or corporal punishment — have significantly lower IQs than children not exposed to such traumas.
But newer studies suggest it's not only extreme kinds of stress that can affect kids' ability to learn and think. In 2009, Virginia Polytechnic Institute and State University scientists found that kids exposed to "household chaos" had lower IQ and more conduct problems. A joint study between Harvard Medical School/McLean Hospital and Catholic University of Korea in 2009 found that children who experienced maternal verbal abuse had lowered verbal IQs and less white matter in their brains. (White matter affects learning by coordinating communication between different regions of the brain.)
