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Moyers on Addiction Stripe
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The Role of Biology and Genetics

Although the brain of an addict is demonstrably different from the brain of a non-addict, researchers are still searching to see whether the brain of a potential addict has unique characteristics, or whether all the differences are caused by the addiction. The addiction process "is a complex interaction between what the drug is doing to the brain, and what the state of the brain was when you started using drugs," says Alan Leshner, Ph.D., director of the National Institute on Drug Abuse.


George Koob, M.D., a professor in the neuropharmacology department at the Scripps Research Institute in La Jolla, California, thinks that the same neurotransmitter systems that are compromised once a person gets addicted may already be abnormal in people vulnerable to addiction. For example, maybe the future addict already has a higher level of stress hormones or a deficit in dopamine function. Koob predicts that in the next 10 to 15 years there will be even greater advances in identifying who is at risk for addiction. Work with PET scans and other imaging technologies, and the ability to visualize neurochemical activity in the brain, will contribute.

Other physical problems such as chronic pain, and mental disorders such as depression, attention-deficit disorder, and chronic anxiety that may have a physical basis in the brain, can also increase vulnerability to addiction.

Inherited Risk

Genetic predisposition is another likely culprit. Researchers have shown relatively conclusively that people with a particular kind of severe, early-onset alcoholism are genetically predisposed to it. In some young men, for example, the risk may be as much as 10-fold greater than in people without that genetic predisposition. In general, children of alcoholics are two to four times more likely to become alcoholics or addicts themselves, reports the federal government's Center for Substance Abuse Prevention. Studies involving adoption have shown that if a person's biological parents were alcoholics, a greater risk for alcoholism persists even if the person was raised by non-alcoholics. And, according to the Addiction Science Research and Education Center at the University of Texas at Austin, more than 60 percent of alcoholics have family histories of alcoholism.

However, not every child of an alcoholic will become alcohol-dependent. Most will not. "Nobody is predestined to become an alcoholic," says Marc Schuckit, M.D., a psychiatrist who teaches at the University of California at San Diego's Medical School. "[Genetics] is one of many factors that you need to look at in order to evaluate your chances of becoming an alcoholic."

The Role of Behavior

Finally, researchers acknowledge that behavior plays a part in triggering addiction. As Leshner points out, many people exposed to multiple risk factors never try drugs of abuse. How frequently, for how long, and how much of a drug is used also helps determine if someone will become addicted. And addicts can learn new behaviors that allow them to recover from their addictions.

-- Janet Firshein


The Role of Biology | "Gateway" Drugs?





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