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Scientists find changes in brain chemistry feed addictions SAN FRANCISCO (February 17, 2001 5:42 p.m. EST http://www.nandotimes.com) - Nora Volkow's images of human brains tell the tale in vivid color: On one side of her slide, the brains of ordinary folks glow bright orange and yellow. On the opposite side, the brains of addicts are a subdued blue and green. A psychiatrist at Brookhaven National Laboratory in New York, Volkow and other researchers are finding that the differences appear consistently whether the addiction is to drugs, alcohol or food and whether the brains in question belong to people, monkeys or rats. The evidence leads them to the growing conviction that addiction is a disease of the brain, not, as many believe, a failure of will. "We've known for 30 years that drugs have their effects by modifying the brain. That's not new," said Alan Leshner, director of the National Institute on Drug Abuse. "What's new is the core concept that although addiction begins with a voluntary behavior called drug abuse, it over time converts into a compulsive behavior called addiction and that actually comes about because of the effects of prolonged drug use on the brain." Scientists trying to track down precisely how drugs change the mind - and figure out ways to reverse the change - gathered Friday to describe their work in San Francisco at the annual meeting of the American Association for the Advancement of Science. "Our goal is to change the national discourse on drug abuse and what to do about it," Leshner said. Plumbing addicts' neurobiology involves tracking brain signals molecule by molecule. One significant difference identified by scientists is in the number of receptors for dopamine, a protein that stimulates brain cells that influence body motion, motivation and the sensation of pleasure. In 16 years of studying hundreds of abusers of cocaine, alcohol, heroin and, more recently, methamphetamine and food, Volkow said she has found that addicts typically possess fewer dopamine receptors, specifically D-2, one of five types of dopamine. Volkow said experiments with monkeys and rats suggest that those with fewer such receptors are more apt to become addicted and that the use of addictive substances shrinks the number of receptors further still. "One of the things that drugs of abuse do is dramatically increase dopamine," Volkow said. "Then dopamine floods the system. ... It's possible that (the brain) resets itself by decreasing the number of receptors to attenuate the effects of the drug." A study by researchers at Wake Forest University in North Carolina with rhesus monkeys suggests this is the case, she said. Monkeys that began with a normal number of receptors ended with fewer after chronic exposure to cocaine. Scientists track the receptors by using radioactive tracers that bind to dopamine receptors, then taking images of the tracers, producing colorful pictures. The story doesn't end there. Check the receptor levels of non-addicts, and you'll find a tremendous variety, Volkow said. Does the level suggest anything about an individual's response to drugs, she wondered. To find an answer, she and colleagues recruited non-addicted volunteers to take Ritalin, a stimulant, and asked if they liked or disliked the effects. The people who said they liked Ritalin had fewer receptors than the people who said they disliked it. Next, Volkow's team wanted to see whether increasing the number of dopamine D-2 receptors would weaken the addiction. They turned rats into alcoholics by giving them alcohol chronically, then injected genes that instructed the brain cells to produce more dopamine receptors. The alcoholic rats subsequently drank much less. The experiment suggests that gene therapy could be useful to treat addicts, Volkow said, but the therapy requires far more work. The effects of gene injections on the rats lasted only a few days. Other treatments researchers are testing aim to block drugs and alcohol from stimulating the brain receptors. The scientific findings about the biology underlying compulsive drug abuse coincide with an apparent softening in attitude by society toward drug users. Last fall, 61 percent of California voters approved a proposition to send some drug offenders to treatment facilities rather than prison. "It's reinforcing the increasingly humanitarian view among the public about who addicts are and what we should do with them," said Dave Fratello of the Campaign for New Drug Policies, which promoted the proposition. But the evidence that long-term drug exposure changes brains also could be used to stigmatize addicts, he said. "It could be kind of dangerous to speak of someone's brain changing, as if it's a permanent situation. ... There's a risk that political forces, the voices of intolerance, could latch onto something like that." Some people simply don't buy the concept of addiction as disease. Laurie McArthur, an Auburn resident trying to close a halfway house in her neighborhood, is one such skeptic. "I smoked for years, and I quit. Simple as that," McArthur said. "My father, same thing. ... I just think where there's a will, there's a way." Leshner acknowledged that some people are able to quit on their own, but they are a distinct minority. "I hope we come to understand that addiction as a brain disease is neither an excuse for addicts or a reason for writing addicts off," he said. Sacramento Bee By EDIE LAU, Sacramento Bee Copyright 2001 Nando Media Copyright 2001 Nando Times janet paterson, an akinetic rigid subtype parkie 53 now / 44 dx cd / 43 onset cd / 41 dx pd / 37 onset pd TEL: 613 256 8340 SMAIL: PO Box 171 Almonte Ontario K0A 1A0 Canada EMAIL: [log in to unmask] URL: http://www.geocities.com/janet313/