Cocaine Addiction Information
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Cocaine’s chemical “switch” stays turned on

By The Associated Press
Sept. 15, 1999

Cocaine may be one of the toughest addictions to cure because it triggers a buildup of a protein that persists in the brain and stimulates genes that intensify the craving for the drug, new research suggests.

The protein (pronounced fawz-bee) isn’t produced in the brain until addicts have used cocaine several times, or even for several years. But once the buildup begins, the need for the drug becomes overpowering and the user’s behavior becomes increasingly compulsive.

“It’s almost like a molecular switch,” said Eric Nestler, who led the research. “Once it’s flipped on, it stays on, and doesn’t go away easily.”

The findings, to be published Thursday in the journal Nature, were called “elegant” and “brilliant” by other researchers who said it offered the first concrete proof that drug use triggers a specific long-term change in brain chemistry.

“Your genes don’t doom you to be an addict,” Leshner said. “They just make you more, or less, susceptible. We’ve never found one gene that keeps you from being an addict, or one that dictates you’re going to be an addict.”

Once the level of Delta-FosB accumulates, it begins to regulate genes that control a region of the brain called the nucleus accumbens, an area involved in addictive behavior and pleasure responses.

To test the theory, they inserted a gene associated with glutamate into the nucleus accumbens of experimental mice. Those mice showed a “dramatic” increase in cocaine sensitivity, they reported.

Other researchers were more cautious, noting that addiction is a complex process in humans because it is linked to learning and multiple chemical pathways in the brain.

The craving for cocaine can be so powerful, a recovered addict who has avoided the drug for years may start feeling his or her heart race just by seeing something associated with drug use, such as a $100 bill or a familiar street corner, Aston-Jones said.

Steve Hyman, director of the National Institute of Mental Health, said the study also indicated the buildup of the Delta-FosB protein might be a factor with other drugs, including amphetamine, morphine, heroin and nicotine.

“This is an important stepping stone but there is a long road to travel,” Hyman said.