LIVING ON IMPULSE

Play hooky, disappear for the weekend, have a fling, binge-shop like
a Wall Street divorcee. Spontaneity can be a healthy defiance of
routine, an expression of starved desire, some psychologists say.

Yet for scientists who study mental illness and addiction, impulsive
behavior -- the tendency to act or react with little thought -- has
emerged as an all-purpose plague.

In recent years, studies have linked impulsiveness to higher risks
of smoking, drinking and drug abuse. People who attempt suicide
score highly on measures of impulsivity, as do adolescents with
eating problems. Aggression, compulsive gambling, severe personality
disorders and attention deficit problems are all associated with high
impulsiveness, a problem that affects an estimated 9 percent of
Americans, according to a nationwide mental health survey completed last year.

Now researchers have begun to resolve the contrary nature of
impulsivity, identifying the elements that distinguish benign
experimentation from self-destructive acts. The latest work, in
brain research and psychological studies, helps explain how impulsive
tendencies develop and when they can lead people astray. A potent
combination of genes and emotionally disorienting early experiences
puts people at high risk, as do some very familiar personal instincts.

"What we're seeing now," said Charles S. Carver, a psychologist at
the University of Miami in Coral Gables, Fla., "is a rapid
convergence of evidence indicating that when the prefrontal cortical
areas of the brain, the brain's supervisory management system, are
not functioning well, this interferes with deliberative behavior, and
the consequences are often unpleasant."

Few experts dispute that impulsiveness pays off in some situations
and, perhaps, had evolutionary benefits. When life is short and
dangerous, and resources are scarce, there is a premium on quick
response. In studies of baboons and monkeys, researchers have found
that animals that are impulsive as adolescents often become dominant
as adults, when they moderate their confrontational urges.

In humans, impulsive behavior typically peaks in adolescence, when
the prefrontal areas of the brain continue to develop, or soon after,
in the young adult years, when it is culturally expected that people
will test their limits, psychologists have found.

Yet new research suggests that a taste for danger or conflict is not
enough to produce persistent, ruinous impulsivity.

In a study published online last month in The Journal of Psychiatric
Research, Janine D. Flory, a psychologist at the Mount Sinai School
of Medicine in Manhattan, led a team of investigators who studied 351
healthy adults and 70 others with impulse-related disorders like
antisocial and borderline personality disorders. The participants
took a battery of tests to measure inhibition, appetite for risk and
the inclination to plan.

Analyzing the responses to questions intended to gauge thrill seeking
like, "I like to explore a strange city or section of town by myself,
even if it means getting lost," and, "I like to try foods I've never
tried before," the researchers found that an appetite for risk was
associated with smoking in both groups.

But in the healthy volunteers, the appetite was also associated with
higher education. In previous studies, healthy risk seekers scored
highly for curiosity and openness to new experiences. On
measurements of instinctive planning - "I am better at saving money
than most people" and "I hate to make decisions based on first
impressions"- the researchers found that less deliberative habits
were related to heavy drinking in the healthy group and the troubled group.

In cases with personality disorders, deficits in planning were also
associated with a history of suicide attempts. The combination of
sensation seeking and lack of deliberation characterizes millions of
healthy people but appears to be extreme in those whose impulsivity
leads to chronic trouble or mental illness, Dr. Flory said.

"The way I think of it is that one factor has to do with the urges
people have, and the other has to do with the brakes they apply," she said.

How and when people apply the brakes is crucial to distinguishing
those who can flirt with regular heroin or cocaine use while
finishing an Ivy League degree and those who die trying.

The people who can binge, gamble or try hard drugs and get away with
it have a native cunning when it comes to risk, this and other
studies suggest. They are prepared for the dangers like a mountain
climber or they sample risk, in effect, by semiconsciously hedging
their behavior - sipping their cocktails slowly, inhaling partly or
keeping one toe on the cliff's edge, poised for retreat.

"These are highly self-directed people," said C. Robert Cloninger, a
professor of psychiatry and genetics at Washington University in
St. Louis and author of "Feeling Good: The Science of Well-Being."
"They have goals and are resourceful in pursuing them."

Those who are upended by their own impulses, by contrast, are more
likely to trust their first impressions implicitly and absolutely,
the studies suggest.

"I am a very intuitive person, I can tell very quickly when someone's
lying to me, when they're telling a shaggy-dog story," said Thomas
Crepeau, 55, a computer systems analyst in Washington who said his
impulsive temper helped worsen a contentious marriage.

Mr. Crepeau, who has since benefited from therapy, said he used to
act on his hunches immediately. "Other people might allow me 20
words before cutting in, but I would allow them four," he said. "I
never had the patience to just wait it out and see if the other
person was wrong."

This difference in ability to hedge or self-regulate is partly based
in genetic variation, experts say. In a study published in March,
investigators at the National Institute of Mental Health took blood
samples from 142 healthy volunteers and analyzed a gene called
MAOA. The gene directs the body to produce an enzyme that reduces
the activity of a brain chemical called serotonin, which strongly
influences mood. Earlier studies have linked variations in this gene
to impulsive aggression.

The researchers conducted M.R.I. scans on participants' brains while
they were performing tasks intended to measure impulse control. In
one of the tests, the participants watched as a computer screen
presented a series of arrows, boxes and X's, three at a time, as a
slot machine does.

The patterns appeared in quick succession, and the participants were
instructed to hit a button indicating which way the arrow was
pointing. They also had to restrain from hitting the button when one
particular pattern appeared. Their mistakes provided a measure of
how well they could restrain their reflexes.

The researchers found that, during the computer game, men who had one
common MAOA variant, known as the "high-risk" variant, showed
significantly less activation than peers with the "low risk" version
of the gene in an area called the dorsal anterior cingulate. The
cingulate is part of the brain's prefrontal area - its supervisory
manager - which is involved in shaping deliberate behavior, in
measuring a proper response or reflex.

The participants in the study with the high-risk gene also had
deficits in areas of the brain involved in moderating emotion,
supporting many earlier studies finding similar gene-related differences.

"On the one hand, these deficits in emotional regulation set people
up for strong emotional reactions early in life and make them more
vulnerable to trauma, we believe," said Dr. Andreas
Meyer-Lindenberg, the study's lead author. "On the other hand, the
deficit in cognitive, inhibitory function creates a propensity to act
on those emotions later in life."

And life never stops testing those supervisory mental skills. Drug
use weakens deliberative regulating skills quickly and cumulatively
over time. Coping with periods of extreme stress at any age -
starting a new job, breaking up with a romantic partner, recovering
from a car accident - can overload the prefrontal regions, leaving
fewer resources available to manage emotions, Dr. Carver said.

One reason true impulsivity has been difficult to capture in the lab,
said Dr. Martha Farrah, director of the Center for Cognitive
Neuroscience at the University of Pennsylvania, is precisely because
"it is most manifest in these very high-stakes situations, when
people are trying to get what they want, to stay focused, maybe
trying to kick a drug habit." And that is when they break down.

None of which is to deny the power of early psychological wounds,
regardless of genetic makeup.

People with borderline personality disorder, for example, an
enigmatic condition characterized by neediness, emotional reactions
and self-destructive behavior like self-mutilation, often misread
others' motives and are savagely impulsive in response. "The
impulsive behavior always has specific meanings for them," said
Dr. Glen Gabbard, a psychiatrist at the Baylor College of Medicine in Houston.

One of his patients, he said, recently called her boyfriend at work,
who told her he couldn't talk just then, he was swamped. She took
that to mean that he was about to dump her.

"She called him back immediately after hanging up and broke up with
him on the spot, as a pre-emptive strike," Dr. Gabbard said.

For her and many others, he said: "It is the psychological meaning of
the event that matters most, and for her it was abandonment. Her own
father left the family when she was 4 years old, and she sees
abandonment everywhere."

In Mr. Crepeau's case, he enrolled in a "compassion power"
group-therapy workshop and learned that his contentious nature grew
in part out of a history of being dismissed and ignored. Once he
understood how this history shaped his impulsiveness, he was able to
begin delaying his reactions.

Mr. Crepeau now teaches workshops that help people deal with
impulsivity and other relationship problems. In a recent class, he
had to contain himself when one of the workshop attendees, asked to
present a homework assignment, took the opportunity to brag at length
about his accomplishments.

"I couldn't believe this guy; not long ago I would have stepped in"
and told him off, Mr. Crepeau said. "But I just waited, and
politely told him he needed to do the assignment over."