How cocaine turns users into addicts


How cocaine turns users into addicts; It tricks brain into thinking it's doing coke for survival;

It is almost as if people were programmed to become cocaine addicts. Deep inside the brain, a small bundle of nerves called the pleasure centre drives human behavior.

Although it accounts for perhaps only four millionths of all the brain cells, it is intertwined with every other brain system.

Through evolution, this pleasure centre has ensured its own survival. As primitive animals developed in a hostile environment, those that derived the most pleasure from chasing, capturing and ultimately eating food were the most likely to thrive.

Those that derived the most pleasure from pursuing mates and engaging in sex were the most likely to reproduce.

Other things being equal, sensitivity to pleasure was an evolutionary advantage, scientists believe. And those pleasure genes spread through subsequent generations.

Now, millions of years later, the human pleasure centre is highly developed, extraordinarily sensitive and dangerously vulnerable. This is the genesis of addiction.

"So much of what we do, so many of our values are driven by the pleasure principle, and people don't want to look at that," said Dr. Charles Dackis of Fair Oaks Hospital in Summit, N.J., one of the U.S.'s leading cocaine-addiction treatment centres.

"We're programmed to procreate, eat food, drink fluids, and the pleasure is what gets organisms to do that. It's in the hardware. Then you get cocaine, which tricks the brain into thinking it's doing something for survival."

Past decade

Cocaine use has evolved in the past decade. The drug was once confined to the rich, particularly people in show business.

"You know who cared? The studio owners," said Dr. Mark Gold, founder of a U.S. national cocaine hotline.

"We even had a counsellor at the Beverly Hills Hotel," he said, because there were no treatment centres.

As supplies increased, cocaine became available to people with less money, and now even the poor can often afford it.

What authorities are worried about, and are beginning to see, is growing use of these more potent forms of cocaine among young people as the price comes down and the purity goes up.

A new smokable form, "crack," evolved partly as a free-enterprise response to the fear of AIDS, because drug users, wary of sharing intravenous needles, wanted an equally potent form of the drug in a more convenient package.

If anything, it turns out, smoking cocaine is more effective than injecting it, reaching the brain in eight seconds instead of 12.

Cocaine is perceived by users as boosting mental and physical ability. In an achievement-oriented era, many students think it helps on their college entrance exams.

"In the short run," said Dr. Jeffrey Rosecan, a drug researcher at Columbia Presbyterian Medical Centre, "it seems to help people perform. People accept this about amphetamines. Why do they have such a hard time accepting it about cocaine?"

Another expert said performance enhancement occurs only when the user is bored or fatigued. With amphetamines, and probably cocaine as well, performance is increased to "pre-fatigue levels," said Dr. Marian M. Fischman of Johns Hopkins University in Baltimore.

It is the search for better performance, both mental and physical, that can lead to addiction in only a few weeks.

"Once you get the notion in your head that it helps you perform, you're in trouble," Rosecan said.

"It's a fine line between feeling that it helps you perform better and that you can't perform without it."

When cocaine is sniffed into the nose, the first effect is numbness from the drug's properties as a local anesthetic. An occasional user, the day after a binge, described a sensation of having "no nose at all."

This anesthetic effect, which made eye surgery painless in the 1880s, results from interference with the electrical signals passing through the nerves. The signals cannot get through, so sensation is temporarily lost.

Opposite occurs

Once the drug reaches the brain, quite the opposite occurs.

There is an immediate sense of power and competence, users say, as if thinking itself had been sped up.

If the cocaine is delivered by injection or smoking, the feeling is more intense.

"You know what it was like?" asked a 27-year-old former crack user in New York. "You feel so incredibly good that regular life doesn't seem good enough. All your problems disappeared for those 45 seconds. It's like a total orgasm of the brain."

In men, said cocaine specialist Dackis, the drug can induce "spontaneous ejaculation." This is an extreme version of a sensation that users and therapists call the "rush," which occurs only when the drug is smoked or injected.

The rush lasts only a few seconds, followed by up to 20 minutes of a high. This short "half-life," as one scientist described it, leads people to use large amounts of cocaine more rapidly than with most other drugs.

The former user in New York, a $50,000-a-year television cameraman, kicked the habit with the help of one of several medications that seem to ease the craving and reduce depression. None of the existing theories fully explains why these medicines work.

But scientists are beginning to agree that cocaine is a two-faced drug, first stimulating the pleasure centre, then squeezing it dry.

Gold and Dackis and other leading reseachers believe that the drug focuses on one particular brain chemical, dopamine.

Dopamine molecules are one of several chemicals that complete circuits in the brain, crossing the tiny fluid-filled gaps, or synapses, between nerve cells.

To send a signal, a nerve cell releases thousands of dopamine molecules, which activate receptors on the next cell. Once the signal is sent, the dopamine molecules return to the synapse, where many of them are reabsorbed by the sending cell and saved for future use.

Cocaine blocks this reabsorption. Instead of being recycled, the dopamine molecules remain in the synapse, stimulating the receptor cell again and again. The circuit remains charged, and the body continues to sense the pleasure or power that the nerves were sending. The heart speeds up; blood pressure rises; sex drive increases.

Over time, however, the effect changes. As the recycling of dopamine continues to be blocked, the build-up in the synapse is washed away. The brain's supply is depleted - "squeezed out," as Rosecan puts it. The sending cells cannot produce dopamine fast enough to make up for the loss. The pleasure circuits are dry. "After a couple of weeks, there is a chemical imbalance in your brain," Rosecan said.

The receptor cells, meanwhile, become supersensitive, agitated, like someone waiting by a phone that refuses to ring. More receptor sites appear in a desperate effort to pick up signals.

"They're saying, 'Give me dopamine,' " Dackis said. "And then they're saying, 'Go get cocaine,' because that will give them dopamine in the short run."

The user becomes depressed, and in a very literal sense he or she is physically unable to experience pleasure without more cocaine, which provides a temporary boost in dopamine levels.

Scientists describe a "vicious cycle" in which cocaine is needed to experience pleasure, but using it only further depletes the dopamine supply in the pleasure centre.

Short term

Most scientists agree that other brain chemicals, or neurotransmitters, are also involved in cocaine addiction, although probably to a lesser extent than dopamine. Some think that cocaine not only blocks reabsorption of dopamine, but also stimulates more production of the brain chemicals in the short term, resulting in the same super-charging of the pleasure centre.

"I don't know how cocaine works," said Dr. Frank Gawin, a Yale University addiction expert. "We don't even know if dopamine is the pleasure-regulating system for certain."

Whether cocaine has become a social problem because the drug itself is exceptionally addictive or because of a combination of social circumstances remains a matter of dispute.

Famous studies have shown that rats and monkeys given free access to cocaine will use it - instead of eating or drinking - until they die, which they will not do with any other drug.

In early experiments, many by Dr. Roy Wise of Concordia University, an electrode implanted in the rat's or monkey's brain could be activated by the animal's pressing a lever. Depending on where the electrode was implanted, pressing the lever produced various sensations. This allowed scientists to find the pleasure circuit.

In later experiments, the electrode in the brain was replaced by a piece of stainless steel tubing attached to a drug reservoir, verifying that chemicals stimulate the pleasure centre.

And in similar experiments in which the drug is delivered intravenously, these animals pass up food and water and simply continue to "lever-press," as the researchers put it.

"Given 24-hour-a-day free access to cocaine, they kill themselves," Wise said.

"Oh, sure, the monkey people will tell you monkeys will self-administer the drug until they die," said Dr. Reese Jones of Langley Porter Institute of the University of San Francisco, who has been studying drug abuse for more than two decades.

In his experience, however, cocaine's effect is contingent on a combination of factors, including the social setting in which it is used.

"In the lab, it's not a dramatic drug," he said. "If you came into our lab right after someone in one room was given an (intravenous) injection of cocaine, and someone in another room had smoked a joint, and someone in another room had drunk a little alcohol, you couldn't tell the three people apart.

"In an hour or two, people are asleep. This is quite different from the Saturday Night Live stereotype of climbing the walls.

Required symptoms

"It's nothing that's particularly unique to cocaine. When you're alone at home and drink alcohol, it has quite a different effect than at a party with a lot of good people."

Until recently, many people did not consider the drug physically addictive because the symptoms of cocaine withdrawal are primarily psychological. Traditional definitions of addiction, as in the cases of alcohol or heroin, required physical symptoms of withdrawal.

"In terms of heroin," said Ron Clark, director of the Rap Inc. drug-treatment program in the District of Columbia, quitting produces symptoms "like a real bad case of flu. The bones ache, you just feel terrible.

"With cocaine, it's depression."

"Cocaine," said Gawin, "is a physically addictive drug where alterations occur in the part of the brain that affects psychology. So the expression of the addiction is psychological."