Dopamine System May Be the Key to Addiction, Reports Nature
Changes in the body's processing of dopamine, a neurotransmitter in the brain, may be the cause of addiction, says a recent study published in the science journal Nature. Researchers at the Brookhaven National Laboratory in New York have strong evidence that an increase in the presence of dopamine in the user's brain is what triggers a cocaine high (N.D. Volkow, et al., "Relationship between subjective effects of cocaine and dopamine transporter occupancy," Nature, April 24, 1997, vol. 386, p. 827; J. Madeline Nash, "Addicted," Time, May 5, 1997, p. 69).
The brain's dopamine process, which is associated with feelings of elation and pleasure, may also explain the "highs" that result from addictions to drugs, sex, and chocolate. Dopamine may be "the master molecule of addiction" which creates intense feelings from any enjoyable activity, according to Time.
The study, which examined seventeen cocaine users, found that a "high" occurred when cocaine occupied at least 47% of the potential sites on the molecules that transport dopamine around the brain. The greatest high happened when cocaine attached to over 60-80% of the sites, thus preventing dopamine from circulating and breaking up. Other drugs, such as heroin, amphetamines, and nicotine trigger the release of quantities of dopamine in the brain that overwhelm the dopamine breakdown process.
These processes suggest that drug addiction may have a biological basis. The dopamine-addiction hypothesis is that a genetic trait, such as an inability to produce enough dopamine, crossed with environmental factors, may create drug dependence. People whose brains produce too little dopamine may suffer from tremors, while those who have too much may experience hallucinations. It is also possible that the "lows" drug addicts experience may result from the brain's efforts to reduce the number of sites that dopamine can bind to.
Responding to the idea that compulsive drug use may be biological, some suggest that the drug war which is focused on criminal prosecution to control drug use, may be pointed in the wrong direction. "In my view, we've got things upside down," said Dr. David Lewis, director of the Center for Alcohol and Addiction Studies at Brown University School of Medicine. "By relying so heavily on a criminalized approach, we've only added to the stigma of drug abuse and prevented high-quality medical care."
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