Boston (CNN) --
Mmmm, a hot fudge sundae. The diet is supposed to start today, but surely it
can wait until tomorrow -- or maybe the next day.
Value judgments and willpower
Pinpointing complex behaviors in the brain isn't simple; we weren't born with the words "impulsivity" and "willpower" etched into particular places on our heads. Scientists are still in the early stages of figuring out how billions of cells called neurons generate particular outcomes, and which circuits do what. But some clues have emerged from recent experiments.When people who are trying to lose weight are confronted with meal choices, it appears there are two major factors in their decision: taste and health, said Todd Hare, assistant professor of neuroeconomics at the University of Zurich.
Hare's research shows
that dieters who successfully turn down fatty temptations such as ice cream put
more emphasis on the healthiness of food and relatively less emphasis on the
taste.
It is the opposite for dieters who can't say "no" to
sweets, he said. They say they're trying to eat healthy, but "they seem
unable to shift away from the more automatic, stronger representation of
taste," Hare said.
By using functional magnetic resonance imaging, or fMRI,
scientists can see how a brain region called the ventral medial prefrontal
cortex becomes active in valuing options in predicaments like this.
The ventral medial prefrontal cortex also appears to get involved
in certain monetary decisions -- for instance, when researchers present
participants with the choice of accepting a large reward later or a smaller
reward immediately. Hare's research on this is not yet published, but the
phenomenon was described in a 2011 research review.
Scientists have also located a second important brain area for
these kinds of decisions: the dorsolateral prefrontal cortex. There is more
activity in this region when participants choose options that appear better for
them in the long run -- the healthy food item or the larger monetary reward
that will arrive later.
The interaction between these two brain regions -- the ventral
medial prefrontal cortex and the dorsolateral prefrontal cortex -- is stronger
for people who show greater self control with either money or food, Hare said.
"They're working together to shape the way you're going to
make your choices."
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Scientists are also investigating brain areas associated with
turning down temptations.
University of Cambridge neuroscientist Molly Crockett and her
colleagues suggested in a study earlier this year that
"precommitment" -- voluntarily restricting one's access to temptation
-- is more effective at promoting self control than willpower.
In the experiment, men viewed erotic images that they rated
according to personal preference. Then, in one task, they could decide in
advance that they would not have the option to see the images they rated
poorly. In exchange, they could see the higher-rated images after a greater
time delay. This is called "precommitment."
In a different task, men were challenged to use willpower to
actively resist viewing the lower-rated images while they waited for the
higher-rated images. Precommitment appeared to be a better strategy on average.
In impulsive participants in particular, researchers saw more
activation in the ventral striatum and ventromedial prefrontal cortex areas
during precommitment. These relationships between brain activation patterns and
impulsive tendencies suggest that people in general may have some
self-awareness about their own self-control abilities.
Are self control problems, such as overeating and overspending,
the result of poor willpower or impaired ability to precommit, or both? Further
research on these issues could help the development of behavioral or
pharmacological interventions, according to the study.
Can we alter brain function for the better?
Currently, we don't have drugs designed to target such brain
impairments associated with lack of self control.
But, in theory, a drug of the future could stimulate key brain
areas to help people with self-control problems diet or save money, according
to David Laibson, professor of economics at Harvard University.
If that sounds too much like science fiction, consider that many
drugs are already on the market to alter brain function for the better -- for
example, methylphenidate (Ritalin) for attention deficit disorder and
anti-depressants for depression.
Outside the pharmacy, there is a drug to combat exhaustion and
enhance attention, used by millions of Americans every day: caffeine. Laibson
argued that if these substances are widely accepted, why shouldn't there be
options for people who want better control of their food decisions?
The practical realities for a self-control drug are complex,
however. Hare cautioned that these brain areas would be hard to target with
medicine because a lot of other brain areas would be hit at the same time. No
drug could selectively increase activity in the dorsolateral prefrontal cortex alone,
for example.
A different approach, which has not been tried, would be to use
transcranial magnetic stimulation to temporarily enhance the activity of
regions of the brain near the skull. This technique -- in which magnetic fields
generate small electrical currents, activating cells in a specified part of the
brain -- is being explored for depression patients who don't respond to
medication.
A 2010 Nature Neuroscience study used
transcranial magnetic stimulation to temporarily inhibit the dorsal lateral
prefrontal cortex, and showed that this led to participants making more
impatient decisions.
Theoretically, this technology could be applied in the opposite
way -- to train relevant brain circuitry to come online during problematic food
choices among dieters, so that eventually the person's brain would respond
naturally in this way, Hare said.
"If there's enough success with this in conditions such as
depression, then I could see that that would be the logical next step,"
Hare said.
Scientists may also be able to develop behavioral interventions
based on brain research -- i.e. how to train and promote self-control.
Psychologists, for example, may be able to derive behavioral therapies from the
"brain circuit differences that we see in people with different kinds of
self control problems," said Joshua Buckholtz, assistant professor of
psychology at Harvard University.
Buckholtz has unpublished research suggesting that people with
high BMIs and non-obese impulsive people have similar brain chemistry patterns.
Committing to change
To recap: We're bad at self control. Scientists are looking at the
brain to figure out how self control breaks down at the neurological level. Such
insights could directly lead to interventions in the form of pharmaceuticals or
brain stimulation.
In the meantime, what can we do to help ourselves behave more in
line with our good intentions, even in the face of temptations?
"The more we recognize the commonality of this problem, the
more prepared we'll be to develop solutions to solve a problem, because the
solutions end up being the same across all the different domains," Laibson
said.
The basis of nonpharmaceutical solutions is the big C-word: commitment.
To some extent, most of us are already entrenched in a system of commitments
that keep us in line. It's called the workplace.
Journalists publish articles, cashiers scan groceries and teachers
grade papers because of systems built into our society that commits them to
perform certain tasks, with the threat of punishment -- or not getting paid --
looming over their heads, Laibson said. Managerial structures ensure that
employees at every level do what they're supposed to be doing.
"We built this system that is actually well tuned to who we
are psychologically," he said. "We're not relying completely on our
willpower to do everything. We are letting the system take care of us."
When it comes to money, for instance, many companies offer savings
plans that automatically place a fixed percentage of your paycheck into a
401(k) account, with strict penalties if you try to access that money before
retirement. Once you sign up, you don't have to think about making the choice
every week; it just happens in the background.
"We don't want people to tell us what to do so that we have
no freedom, but we do need a little bit of help so that we actually get to work
and have a productive day instead of rolling in at 11 a.m.," Laibson said.
Applying that method to food is a lot trickier. Your boss can make
you go to a 9 a.m. meeting, but you don't have a Food Manager who prods you to
avoid potato chips and count calories at every single meal. Even if your
workplace's cafeteria has reasonably sized portions, including small desserts,
no one will stop you from buying two or three cookies.
To encourage healthy habits in an already structured workplace,
companies could instead institute standing desks and hold standing or even
"walking meetings," in which people move around while they discuss
business instead of sit in a conference room. These interventions should,
however, be tested scientifically before being widely promoted, Laibson said.
Government intervention is another way that self control could be
imposed, but a controversial one. The city of New York tried to limit sugary drinks sold to 16
ounces each last year, but an appeals court ruled in July that this was
"arbitrary and capricious." In Laibson's view, such a policy needs
scientific evidence that it has positive health outcomes before being broadly
enacted.
But you don't necessarily need a boss or government official
threatening to punish you for breaking rules you already want to follow for the
sake of your health. You can set up a system in which you discipline yourself.
Through the Internet, you can wager your own money to commit
yourself to your own diet and exercise aspirations. A website calledStickK allows
you to put your own money on the line in support of whatever goal you may have;
if you don't fulfill it, you lose the money. As Yale economist Dean Karlan,
co-founder of StickK, told CNN in 2008,
"It's a contract to make slothfulness more expensive."
So, think how much money your health-conscious self would offer
your sweet-tooth self to keep the ice cream in the freezer, or not buy it at
all.
