Brain Rules: 12 Principles for Surviving and Thriving at Work, Home, and School (18 page)

the villain, the hero

The biology behind this obvious assault on our intelligences can be described as a tale of two molecules, one a villain, the other a hero. The villain is the previously discussed cortisol, part of a motley crew of hormones going by the tongue-twisting name of glucocorticoids (I’ll call them stress hormones). These hormones are secreted by the adrenal glands, which lie like a roof on top of your kidneys. The adrenal glands are so exquisitely responsive to neural signals, they appear to have once been a part of your brain that somehow fell off and landed in your mid-abdomen.

Stress hormones can do some truly nasty things to your brain if boatloads of the stuff are given free access to your central nervous system. That’s what’s going on when you experience chronic stress. Stress hormones seem to have a particular liking for cells in the hippocampus, and that’s a problem, because the hippocampus is deeply involved in many aspects of human learning. Stress hormones can make cells in the hippocampus more vulnerable to other stresses. Stress hormones can disconnect neural networks, the webbing of brain cells that act like a safety deposit vault, storing your most precious memories. They can stop the hippocampus from giving birth to brand-new baby neurons. Under extreme conditions, stress hormones can even kill hippocampal cells. Quite literally, severe stress can cause brain damage in the very tissues most likely to help your children pass their SATs.

The brain seems to be aware of all this and has supplied our story not only with a villain but also with a hero. We met this champion back in the Exercise chapter. It’s the Brain Derived Neurotrophic Factor. BDNF is the premier member of the powerful group of proteins called neurotrophins. BDNF in the hippocampus acts like a standing military armed with bags of Miracle Gro, keeping neurons alive and growing in the presence of hostile action. As long as there is enough BDNF around, stress hormones cannot do their damage. As I said, BDNF is a hero. How, then, does the system break down?

The problem begins when too many stress hormones hang around in the brain too long, a situation you find in chronic stress, especially of the learned helplessness variety. As wonderful as the BDNF fertilizer armies are, it is possible to overwhelm them if they are assaulted with a sufficiently strong (and sufficiently lengthy) glucocorticoid siege. Like a fortress overrun by invaders, enough stress hormones will eventually overwhelm the brain’s natural defenses and wreak their havoc. In sufficient quantities, stress hormones are fully capable of turning off the gene that makes BDNF in hippocampal cells. You read that right: Not only can they overwhelm our natural defenses, but they can actually turn them
off
. The damaging effects can be long-lasting, a fact easily observed when people experience catastrophic stress.

You might recall the bodyguard who was in the car with Princess Diana on the night of her death. To this day, he cannot remember the events several hours before or after the crash. That is a typical response to severe trauma. Its lighter cousin, forgetfulness, is quite common when the stress is perhaps less severe but more pervasive.

One of the most insidious effects of prolonged stress is that it pushes people into depression. I don’t mean the type of “blues” people can experience as a normal part of daily living. Nor do I mean the type resulting from tragic circumstance, such as the death of a relative. I am talking about the kind of depression that causes as many as 800,000 people a year to attempt suicide. It is a disease every bit as organic as diabetes, and often deadlier.

Chronic exposure to stress can lead you to depression’s doorstep, then push you through. Depression is a deregulation of thought processes, including memory, language, quantitative reasoning, fluid intelligence, and spatial perception. The list is long and familiar. But one of its hallmarks may not be as familiar, unless you are in depression. Many people who feel depressed also feel there is no way out of their depression. They feel that life’s shocks are permanent and things will never get better. Even when there is a way out—treatment is often very successful—there is no perception of it. They can no more argue their way out of a depression than they could argue their way out of a heart attack.

Clearly, stress hurts learning. Most important, however, stress hurts
people
.

a genetic buffer

In a world as complex as the brain, is the relationship between stress and learning that straightforward? For once, the answer is yes. Out-of-control stress is bad news for the brains of most people. Of course, most doesn’t mean all. Like oddly placed candles in a dark room, some people illuminate corners of human behavior with unexpected clarity. They illustrate the complexity of environmental and genetic factors.

Jill was born into an inner-city home. Her father began having sex with Jill and her sister during their preschool years. Her mother was institutionalized twice because of what used to be termed “nervous breakdowns.” When Jill was 7 years old, her agitated dad called a family meeting in the living room. In front of the whole clan, he put a handgun to his head, said, “You drove me to this,” then blew his brains out. The mother’s mental condition continued to deteriorate, and she revolved in and out of mental hospitals for years. When Mom was home, she would beat Jill. Beginning in her early teens, Jill was forced to work outside the home to help make ends meet.

As Jill got older, we would have expected to see deep psychiatric scars, severe emotional damage, drugs, maybe even a pregnancy or two. Instead, Jill developed into a charming and quite popular young woman at school. She became a talented singer, an honor student, and president of her high school class. By every measure, she was emotionally well-adjusted and seemingly unscathed by the awful circumstances of her childhood.

Her story, published in a leading psychiatric journal, illustrates the unevenness of the human response to stress. Psychiatrists long have observed that some people are more tolerant of stress than others. Molecular geneticists are beginning to shed light on the reasons. Some people’s genetic complement naturally buffers them against the effects of stress, even the chronic type. Scientists have isolated some of these genes. In the future, we may be able to tell stress-tolerant from stress-sensitive individuals with a simple blood test, looking for the presence of these genes.

the tipping point

How can we explain both the typical responses to stress, which can be quite debilitating, and the exceptions? For that, we turn to a senior scientist, Bruce McEwen, an elder statesman, smart, always in a suit and tie.

McEwen developed a powerful framework that allows us to understand all the various ways humans respond to stress. He gave it a name straight out of a
Star Trek
engineering manual: allostasis. Allo is from a Greek word meaning variable; stasis means a condition of balance. The idea is that there are systems that help keep the body stable by changing themselves. The stress system in the human body, and its many intricate subsystems, is one of those. The brain coordinates these body-wide changes— behavior included—in response to potential threats.

This model says that stress, left alone, is neither harmful nor toxic. Whether stress becomes damaging is the result of a complex interaction between the outside world and our physiological capacity to manage the stress. Your body’s reaction to stress depends on the stress, on its length and severity, and on your body. There’s a point where stress becomes toxic, and McEwen calls it the allostatic load. I know it as the first time, and only time, I ever heard my mother use profanity. I also know it as the time I got the worst grade in my academic career. We all have stories that illustrate the concrete effects of stress on real life.

As you may recall, my mother was a fourth-grade teacher. I was upstairs in my room, unbeknownst to my mother, who was upstairs in her room grading papers. She was grading one of her favorite students, a sweet, brown-haired little wisp of a girl I will call Kelly. Kelly was every teacher’s dream kid: smart, socially poised, blessed with a wealth of friends. Kelly had done very well in the first half of the school year.

The second half of the school year was another story, however. My mother sensed something was very wrong the moment Kelly walked into class after Christmas break. Her eyes were mostly downcast, and within a week she had gotten into her first fight. In another week, she got her first C on an exam, and that would prove to be the high point, as her grades for the rest of the year fluttered between D’s and F’s. She was sent to the principal’s office numerous times, and my mother, exasperated, decided to find out what caused this meltdown. She learned that Kelly’s parents had decided to get a divorce over Christmas and that the family conflicts, from which the parents valiantly had insulated Kelly, had begun spilling out into the open. As things unraveled at home, things also unraveled at school. And on that snowy day, when my mother gave Kelly her third straight D in spelling, my mother also swore:

“Dammit!” she said, nearly under her breath. I froze as she shouted, “THE ABILITY OF KELLY TO DO WELL IN MY CLASS HAS NOTHING TO DO WITH MY CLASS!”

She was, of course, describing the relationship between home life and school life, a link that has frustrated teachers for a long time. One of the greatest predictors of performance in school turns out to be the emotional stability of the home.

stress in the home

I want to focus on stress in the home because it is profoundly related to kids’ ability to do well in the classroom and, when they grow up, in the workforce.

Consider the all-too common case of kids witnessing their parents fighting. The simple fact is that children find unresolved marital conflict deeply disturbing. Kids cover their ears, stand motionless with clenched fists, cry, scowl, ask to leave, beg parents to stop. Study after study has shown that children—some as young as 6 months—react to adult arguments physiologically, such as with a faster heart rate and higher blood pressure. Kids of all ages who watch parents constantly fight have more stress hormones in their urine. They have more difficulty regulating their emotions, soothing themselves, focusing their attention on others. They are powerless to stop the conflict, and the loss of control is emotionally crippling. As you know, control is a powerful influence on the perception of stress. This loss can influence many things in their lives, including their schoolwork. They are experiencing allostatic load.

I have firsthand experience with the effects of stress on grades. I was a senior in high school when my mother was diagnosed with the disease that would eventually kill her. She had come home late from a doctor’s visit and was attempting to fix the family dinner. But when I found her, she was just staring at the kitchen wall. She haltingly related the terminal nature of her medical condition and then, as if that weren’t enough, unloaded another bombshell. My dad, who had some prior knowledge of Mom’s condition, was not handling the news very well and had decided to file for divorce. I felt as if I had just been punched in the stomach. For a few seconds I could not move. School the next day, and for the next 13 weeks, was a disaster. I don’t remember much of the lectures. I only remember staring at my textbooks, thinking that this amazing woman had taught me to read and love such books, that we used to have a happy family, and that all of this was coming to an end. What she must have been feeling, much worse than I could ever fathom, she never related. Not knowing how to react, my friends soon withdrew from me even as I withdrew from them. I lost the ability to concentrate, my mind wandering back to childhood. My academic effort became a train wreck. I got the only D I would ever get in my school career, and I couldn’t have cared less.

Even after all these years, it is still tough to write about that high school moment. But it easily illustrates this second, very powerful consequence of stress, underscoring with sad vengeance our Brain Rule: Stressed brains do not learn the same way as non-stressed brains. My grief at least had an end-point. Imagine growing up in an emotionally unstable home, where the stress seems never-ending. Given that stress can powerfully affect learning, one might predict that children living in high-anxiety households would not perform as well academically as kids living in more nurturing households.

That is exactly what researchers have found. Marital stress at home can negatively affect academic performance in almost every way measurable, and at nearly any age. Initial studies focused on grade-point averages over time. They reveal striking disparities of achievement between divorce and control groups. Subsequent investigations showed that even when a couple stays together, children living in emotionally unstable homes get lower grades. (Careful subsequent investigations showed that it was the presence of overt conflict, not divorce, that predicted grade failure.) They also do worse on standardized math and reading tests.

The stronger the degree of conflict, the greater the effect on performance. Teachers typically report that children from disrupted homes rate lower in both aptitude and intelligence. Such children are three times as likely to be expelled from school or to become pregnant as teenagers, and five times as likely to live in poverty. As social activist Barbara Whitehead put it, writing for the
Atlantic Monthly:
“Teachers find many children emotionally distracted, so upset and preoccupied by the explosive drama of their own family lives that they are unable to concentrate on such mundane matters as multiplication tables.”