Pubdate: Sun, 13 Jun 1999 Source: Santa Fe New Mexican (NM) Copyright: 2000 The Santa Fe New Mexican Contact: 202 E Marcy, Santa Fe, N.M. 87501 Fax: (505) 986-3040 Feedback: http://www.sfnewmexican.com/letterstoeditor/submitform.las Website: http://www.sfnewmexican.com/ Author: Barbara Ferry 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.