Narcolepsy Drug Eyed for Cocaine Users

Graphic shows cocaine users admitted for substance abuse treatment and percentage using cocaine by state. (AP Graphic) (AP)

_Potentially more important, he says, modafinil seems to increase activity in the prefrontal cortex, the brain's decision-making command center and the spot that allows reasoning to override impulse or emotion. Cocaine reduces activity in that key brain region, making it even harder for would-be quitters to ignore cravings and resist another hit.

_Modafinil also increases the ability to think strategically, a means of weighing variables and risks to make decisions, says Frank Vocci, NIDA's pharmacotherapy chief.

"The effects on cognitive processes are very subtle, and very interesting," Vocci says _ and that's the reason that of half a dozen medications being studied as potential cocaine treatments, the government's biggest emphasis is on modafinil.

Cocaine is highly addictive: About 16 percent of people who try it become hooked, often rapidly. In 2003, the latest data, the government estimated that more than 1.5 million Americans were dependent on or abusing cocaine, and more reported recently experimenting with it.

Addictions in general rewire the brain, says Volkow, the NIDA director. Drugs cause a feel-good rush by increasing amounts of the brain chemical dopamine. The brain reacts by tamping down regular dopamine production, making users feel lousy between hits and setting up the cycle of addiction.

At the same time, the dopamine surge also creates memory circuits that eventually establish so-called "cue-induced cravings": If an addict passes the crack house or sees friends he did drugs with, his brain literally sends a strong impulse to use again.

"One of the strategies of course, in terms of treatment ... is how can we help recover the function of the dopamine system, so the person that's addicted can become sensitive to natural stimuli," Volkow explains.

Modafinil seems to affect chemicals that in turn regulate dopamine production, a different pathway than cocaine takes in altering normal dopamine, and thus one that might counter it, adds Dackis.

"You can't assume this is going to work," he cautions. But if it pans out, a drug that could help cognition instead of just numb cravings would be "a big benefit in treatment."

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EDITOR'S NOTE _ Lauran Neergaard covers health and medical issues for The Associated Press in Washington.