HOW DRUG SKEWS VALUES

Brain Scans Show That Cocaine Addicts Seem Less Motivated To Work
Harder For More Money

People who abuse cocaine may be damaging brain regions that motivate
people to work harder for greater monetary rewards, and may extend
to other nondrug rewards such as food, too, according to a new
study. It could also make recovery from addiction more difficult.

"The problems in the brain's reward processing area and the control
ofbehavior could explain why people have such a hard time stopping,"
said Rita Goldstein, a scientist at Brookhaven National Laboratory
and lead investigator in the study.

She and her colleagues have identified disruptions in the brain's
prefrontal cortex, the area that governs thinking, planning and behavior.

When addicts were asked to complete a number of computer-driven
tests - a correct response would lead to rewards totaling $50 -
brain scans showed that the amount of money they could make had no
impact on their response. But volunteers with no history of drug
use performed better if they knew the reward was higher.

In other words, one of the most powerful rewards that drive human
behavior - money - didn't seem to register a normal brain response,
said Goldstein, who presented the latest findings during the Society
for Neuroscience annual meeting in Atlanta this week.

"The drug overpowers the brain regions that respond to nondrug
rewards like money," said Goldstein, who says that the ability to
seek other rewards like food and sex may also be compromised by the
changes to this region.

Goldstein and her colleagues also asked people in the study, 16
addicts and 13 healthy volunteers, how much they value money.
Goldstein said more than half of the cocaine addicts said that $10
was just as good as $1,000, compared with two of the 13 healthy volunteers.

Test subjects had to tap a button on cue, or not tap a button when
shown another cue. The normal volunteer's orbitofrontal gyrus - a
part of the prefrontal cortex - became more active when the reward
was greater and less active with a smaller sum.

This response - the higher the reward, the more brain activity - did
not show up in the cocaine users. The responses showed no difference
in activity, whether the reward was high or low.

The scientists also measured responses by placing electrodes across
the scalp to check electrical activity inside the brain. The more
active a person's prefrontal cortex, the more the subject understood
the difference between low and high monetary rewards, she added.

Goldstein says that these changes "may be related to their ability
to make decisions and control their behavior."

If someone is not motivated by a nondrug reward, it can't be used to
control their behavior, she added.

"One is bound to make some disadvantageous decisions."

This includes continued drug use, she said.