Brain Scans Reveal Cocaine Effects

By The Associated Press

BOSTON (AP) For the first time, highly detailed scans of cocaine
addicts' brains have revealed the precise circuits that are turned on
during the drug's initial rush, the euphoria and the craving that
inevitably follows.

The technique, which uses a new kind of brain imaging, has given
researchers a longsought peek at precisely what's going wrong biologically
inside the head during an attack of a mental disorder in this case, drug
addiction.

Dr. Hans Breiter of Massachusetts General Hospital, who conducted the
experiment, described the new technology as achieving a sort of Holy Grail
of psychiatry.

``These studies are a direct attempt to build a neuroscience foundation for
psychiatry,'' Breiter said. ``If Sigmund Freud was still around, he would
be doing these studies.''

With this new tool, Breiter said it should be possible to explore drugs
that literally shortcircuit the effects of cocaine on the brain as a way
of breaking addiction.

>From the brain images, researchers found that about 90 distinct parts of
the brain are turned on during the brief cocaine rush and the plateau of
euphoria that follows it. This is considerably more than they had imagined
were involved.

As the pleasant feelings begin to ebb, the researchers found, most of these
brain areas fall inactive again, leaving just 13 still lit up. And with
these remaining brain circuits come the fierce craving for more cocaine.

``What you are literally looking at is what happens in the brain of an
addict as their experiences change during the course of a single drug
exposure. That is unbelievable,'' commented Dr. Alan Leshner, director of
the National Institute on Drug Abuse.

A report on the research is being published in the September issue of the
journal Neuron.

The key to the new images is a kind of brain scan called functional
magnetic resonance imaging, or fast MRI. Like standard MRIs used in many
big hospitals, these employ powerful magnets to produce crosssectional
pictures of the body. But unlike the usual slowworking machines, these
rattle off clear pictures of the brain about every 20 seconds, providing a
movielike chronology of changes.

The parts of the brain that go to work during a cocaine high use more
oxygen than resting brain cells. The MRI pinpoints them by tracking
oxygenladen blood, which has a slightly different magnetic profile than
blood that is depleted of oxygen.

In their experiment, the researchers performed 13minute scans on 10
volunteers all cocaine addicts while they got cocaine injections.

Typically, a round of cocaine triggers a socalled rush, a minute or so of
exquisitely intense racing feelings, as the heart speeds up and sweat
breaks out. This is followed by perhaps five to eight minutes of high, when
people may feel euphoric, talk nonstop and crave sex. Next comes an
overwhelming urge for more cocaine in which users will do almost anything
to get another dose. This can last for a day.

As the volunteers described their feelings, the scientists viewed the
neurons activated inside their brains at that moment.

The researchers were especially intrigued by the circuits left on when the
craving set in, because this provided the first confirmation in people of
addiction research in animals. In both lab animals and humans, it appears,
cocaine triggers the amygdala and the nucleus accumbens, brain areas
thought to play a role in reward reinforcement.