Pubdate: Mon, 05 Mar 2001 Source: New York Times (NY) Copyright: 2001 The New York Times Company Contact: 229 West 43rd Street, New York, NY 10036 Fax: (212) 556-3622 Website: http://www.nytimes.com/ Forum: http://forums.nytimes.com/comment/ Author: Sandra Blakeslee Bookmark: http://www.mapinc.org/meth.htm (methamphetamine) DRUG'S EFFECT ON BRAIN IS EXTENSIVE, STUDY FINDS Heavy users of methamphetamine - a highly addictive stimulant that can be made at home in the kitchen sink - are doing more damage to their brains than scientists had thought, according to the first study that looked inside addicts' brains nearly a year after they stopped using the drug. At least a quarter of a class of molecules that help people feel pleasure and reward were knocked out by methamphetamine, the study found. Some of the addicts' brains resembled those of people with early and mild Parkinson's disease. But the biggest surprise is that another brain region responsible for spatial perception and sensation, which has never before been linked to methamphetamine abuse, was hyperactive and showed signs of scarring. On tests of memory, attention and movement, the methamphetamine addicts did worse compared with people who do not use drugs, the study reported. The researchers said it was too soon to know if people who stopped taking the drug for more than a year would recover lost brain function. The study was led by Dr. Nora Volkow, associate director for life sciences at the Brookhaven Haven National Laboratory in Upton, N.Y., and appears in the March issue of The American Journal of Psychiatry. This is the first study to show directly that brain damage caused by methamphetamine produces deficits in learning and memory, said Dr. Alan Leshner, director of the National Institute on Drug Abuse, which helped finance the new research. Use of the drug has reached epidemic proportions in Hawaii, California and parts of the Midwest, he said. Made in clandestine laboratories from cheap ingredients, it is known as speed, meth, chalk, ice, crystal and glass. The drug can be smoked, snorted, injected or taken by mouth. A $5 dose produces euphoria and increases energy for hours, whereas a cocaine high may last only half an hour. It's not clear why some people choose cocaine over methamphetamine or vice versa, Dr. Volkow said. Estimates are that five million American have experienced methamphetamine and maybe one million to two million are regular users. "It's a bigger problem that heroin," she said. Over the years, the addicts in the study had taken pounds of methamphetamine, an amount that is enough to kill laboratory animals, Dr. Volkow said. "Actually, I am stunned these people are not dead." In the study, Dr. Volkow used an imaging technique called positron emission tomography to measure dopamine levels in the brains of 15 recovering addicts and 18 healthy volunteers. Dopamine is a brain chemical that regulates movement, attention, pleasure and motivation. When the dopamine system goes seriously awry, she said, people lose their excitement for life and can no longer move their limbs. Their brains were then imaged a second time to measure how different parts of their brains metabolize energy. The addicts smoked or injected methamphetamine all day for several years, Dr. Volkow said. They had started out as occasional users but over time the drug hijacked their natural dopamine systems. Two weeks after the brain images were taken, the addicts and the volunteers were brought back to the laboratory and asked to do tasks like walking as fast as possible in a straight line, rapidly inserting pegs into small holes angled in different directions, matching numbers with symbols, recalling lists of unrelated words and carrying out other tests that measure brain acuity. On average, dopamine was 24 percent lower in addicts than in normal volunteers, Dr. Volkow said. They were clumsier at putting pegs in the holes and had difficulty remembering words. Half the addicts said they felt their brains were not working as well as they used to. But the study's biggest surprise was that the addicts' parietal lobes, the parts of the brain used for feeling sensation and recognizing where the body is in space, were metabolically overactive, Dr. Volkow said. Other studies showed that metabolism increased when the brain suffered traumatic injury or got high doses of radiation, she said. It is the equivalent of an inflammation or scarring response. The loss of dopamine is also worrisome, Dr. Volkow said. Three drug abusers had dopamine levels that fell within the range seen in patients with low-severity Parkinson's disease. Because dopamine levels fall naturally with age, it's unclear what will happen to these people 30 years from now. "We don't know if they will recover dopamine function or not," she said. Five of the fifteen addicts have not relapsed and are being re-examined with brain imaging to see if their dopamine levels rebound. All smoke heavily, and it may be that nicotine protects their brains from being more severely damaged, she said. If that is the case, treatments for methamphetamine abuse might include nicotine patches and drugs to enhance dopamine function along with behavioral therapy. - --- MAP posted-by: Larry Stevens