SCIENCE AND ADDICTION

Researchers Hope To Find Reasons For Short-term Treatment's Failure

Remember those commercials that had an egg frying in a pan and a
disembodied voice saying, "This is your brain on drugs"?

Researchers are now using brain scans to examine what brains actually look
like on drugs. When they compare the scans to normal brains, they find
significant differences.

A discarded syringe litters the landscape during a May anti-drug march in
Chimayo.

The studies are helping to explain why it's easier to quit drugs than to
stay clean, as well as providing clues about why short-term drug-treatment
programs often fail.

The brain scans, along with animal experiments, indicate that
addictivedrugs change not only the chemistry of the brain but its physical
appearance as well. The changes remain long after the addiction ends.

"Prolonged drug use changes the brain in fundamental and lasting ways," Dr.
Alan Leshner, director of the National Institute on Drug Abuse, wrote in a
summary of recent research.

Changes in brain chemistry and physiology are not unique to drug use.
They're also caused by positive experiences, such as learning. But chronic
drug use "tricks" the brain, researchers say, short-circuiting its natural
reward system in ways that might be permanent.

In a study published in 1996, researchers at Yale University gave rats
regular doses of morphine. When the rats' brains were examined, the
researchers found the cells that produce dopamine - a chemical involved in
the pleasure-and-reward process - had shrunk.

The dopamine neuron is the same circuit that is activated by pleasurable
activities such as eating and sex. Drugs also activate the circuit,
boosting dopamine levels, only more intensely. Short-acting narcotics such
as heroin cause a sharp spike in dopamine levels.

Researchers speculate that after chronic exposure to the drugs, the
dopamine-producing cells adapt by shrinking to compensate for the increased
activity.

These shrunken cells might explain why as addiction progresses, heroin
users stop getting high and require greater and greater doses to simply
stop themselves from feeling sick.

"These changes are the brain's way of adapting to the drug sledgehammer,"
says Dr. Steven Hyman, director of the National Institute of Mental Health.
Hyman also heads a molecular biology laboratory at Harvard University that
studies the dopamine pathway.

When morphine is withheld, the shrunken cells contribute to the bad
feelings associated with withdrawal.

Other studies indicate addictive drugs not only release elevated levels of
dopamine, but they also block the dopamine from returning to the brain
cells that produced them, as they would under normal circumstances.

One study that examined brain scans of 17 chronic cocaine users found that
high doses of cocaine blocked dopamine transporters.

Hyman says these brain changes are reversible.

"If people stay clean, most of these adaptations seem to normalize over a
period of weeks to months," Hyman says.

But another type of brain change caused by drugs might be permanent.

"The more nefarious changes are the ones that hijack your brain's mechanism
for learning things," Hyman says. "Unlearning something is very difficult.
Think about trying to unlearn how to ride a bike."

Researchers have found that "environmental cues" such as being in the
presence of drug paraphernalia and drug-using friends trigger specific
changes in former addicts, such as changes in heart rate, blood pressure
and pupil size.

These gut-level emotional memories, or "memories of the high," might
present the biggest challenge to beating addiction.

"Everything associated with drug use gets painted with these unnaturally
high dopamine levels," Hyman says. "So you come into contact with your old
drug-using friends, you may feel intense desire for the drugs and that may
initiate an automatic, almost ritualistic, behavioral reaction to use them.
Unfortunately we're not yet very good at providing people with therapies to
see them through these profound altered systems.

"And unfortunately, these changes may be forever."

Dr. Charles O'Brien, an addiction specialist at the University of
Pennsylvania, says that given what researchers are learning about
addiction, the public's expectations of drug treatment might be unrealistic.

"The general public expects addictions to be cured, like a broken leg,"
O'Brien says. "But addiction is more like a chronic disorder. You can
induce remission but most people are going to relapse. I wish we could cure
people once and for all, but unfortunately we can't."

At the same time, researchers caution that the common assumption about
addiction - that drug addicts are just people who take a lot of drugs - is
false.

"There is a difference between intentional drug abuse and pathological drug
dependence," says Dr. Carleton Erickson, a researcher at the University of
Texas at Austin. "Everybody who uses large amounts of drugs over a long
period of time is not necessarily addicted."

Based on surveys of drug users, O'Brien thinks about 23 percent of people
who have used heroin become addicted. The percentage for nicotine is
higher: 32 percent.

O'Brien describes addiction as an interactive situation, similar to an
environment where there is an infectious disease going around. Whether a
person gets infected depends on a number of factors: the infectious agent,
the health and genetic makeup of the host and the general environment.

Researchers define addiction by the power it exerts over the drug user's life.

While a casual drug user will quit when the consequences of using become
serious enough - such as a job requiring a clean drug test - the addict is
unable to stop using drugs even when faced with serious consequences, such
as incarceration or having children taken away from them.

The findings suggest that punitive measures aimed at getting people to stop
taking drugs might be ineffective with true addicts.

They also help explain why an estimated 80 percent of drug users who
undergo short-term detox without follow-up treatment return to using drugs
within a year.

Appropriate therapy, Hyman says, "would ideally be to find a different
life, where you wouldn't come into contact with the people who trigger
drug-using behavior."

Alternatively, he said, treatment specialists must help recovering addicts
plan how to cope with these triggers.

"Unfortunately these forces are powerful enough that they often tragically
cause a lapse into drug use," he says.