Brain Rules (Updated and Expanded)

off
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A genetic buffer
Out-of-control stress is bad news for the brains of most people. But 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,” and 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

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individuals with a simple blood test, looking for the presence of these
genes.
We each have our own tipping point
How can we explain the various ways humans respond to stress—both the
typical cases and the exceptions? The answer is that stress is neutral.
Aversive stimuli are neither beneficial nor bad. Whether stress becomes
damaging depends on the severity of the stress, how long you are exposed
to the stress, and on your body’s ability to handle stress. There’s a tipping
point where stress becomes toxic. Scientist Bruce McEwen calls it the
allostatic load. 
Allo
is from a Greek word meaning variable; 
stasis
means a
condition of balance. McEwen’s idea is that we have systems that keep us
stable by constantly changing themselves. The stress system, with all of its
intricacies, is one of those. The brain coordinates body-wide changes—
from hormonal to behavioral changes—in response to the approach and
retreat of potential threats.
Stress at home shows up at school
I know the allostatic load as the first time, and only time, I ever heard my
mother swear. 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 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, which would prove to be the high point, as her grades for the rest of
the year fluttered between Ds and Fs. 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.

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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: “Damn it!” 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 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.
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 knew 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
continually 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 time in my
life. But it effectively illustrates Brain Rule #4: Stressed brains do not learn
the same way as non-stressed brains.
My grief at least had an end point. In an emotionally unstable home, the
stress seems never-ending. Consider the all-too-common case of children
witnessing their parents fighting. The simple fact is that kids find
unresolved marital conflict deeply disturbing. They cover their ears, stand
motionless with clenched fists, cry, scowl, ask to leave, beg parents to stop.

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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, and focusing their attention
on others. They are powerless to stop the conflict, and the loss of control is
emotionally crippling. As you know, perception of control is a powerful
influence on the perception of stress. They are experiencing allostatic load.
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 studies show. 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, revealing striking
disparities in achievement between kids whose parents are going through a
divorce and control groups. Even when a couple stays together, children
living in emotionally unstable homes get lower grades and do worse on
standardized tests of math and reading. Careful subsequent investigations
showed that it was the presence of overt conflict, not divorce, that predicted
grade failure.
The stronger the degree of conflict, the greater the effect on
performance. When teachers are asked to rate children’s intelligence and
aptitude, children from homes with conflict score lower. Such children are
three times more likely to be expelled from school or to become pregnant as
teenagers, and five times more likely to live in poverty. As social activist
Barbara Whitehead put it, writing for the