Pubdate: Tue, 02 Oct 2001
Source: The Herald-Sun (NC)
Copyright: 2001 The Herald-Sun
Contact:  http://www.herald-sun.com
Details: http://www.mapinc.org/media/1428
Author: AP

STUDY LOOKS AT REASONS FOR ADDICTS' RELAPSES

ANN ARBOR, Mich. -- Ex-smokers, drug addicts or alcoholics are vulnerable 
to relapses when exposed to such mundane reminders as ice cubes, cigarettes 
or the sight of needles.

It has long been known associations of an addiction -- such as coffee that 
goes with cigarettes for some smokers -- can trigger a craving, said 
University of Michigan psychologist Kent Berridge.

His research on rats, published in Monday's edition of the Journal of 
Neuroscience, looked at the neurology of why such innocent cues as a cup of 
coffee can cause a relapse.

"One big question is does sensitization happen in addicts," Berridge said.

Drug use, he said, can "sensitize" certain brain systems. One brain system, 
often called the dopamine system, is activated by drugs, releasing more 
dopamine than normal when drugs are subsequently taken.

That dopamine system also is activated by cues that go along with an 
addiction, he said. Berridge said his experiment suggests that brains 
sensitized by drug use may remain vulnerable to cues that trigger 
irrational "wanting" of drugs, even after a long period of abstinence.

His theory is that a sensitized brain may have extra wanting for a drug, 
even when an addict no longer likes it, if a cue is present.

"Addition is a complex phenomena," said Dr. David Friedman, a professor of 
physiology at Wake Forest University. "It's reasonable to propose that 
sensitization plays a role in that."

Using rats taught to press a lever to get sugar pellets, and to associate 
that sugar with a 30-second sound, Berridge then injected the animals with 
amphetamine. Next, he waited until the rats were drug-free. When rats who'd 
been exposed to drugs heard the sound cue, they'd frantically try to press 
a lever to get sugar, Berridge said.

"Whenever a sugar cue occurred, rats pressed in a frenzy. ... They would 
press 300 percent what a normal rat would press when the cue is there," he 
said.

"We're thinking this is a model for addicts," Berridge said. "But is it 
happening in addicts? Sensitization probably doesn't happen in everybody, 
because it doesn't happen in all rats.

"So some people are at risk for addiction, and it hinges on whether they're 
vulnerable to sensitization."

Berridge said more research remains to understand how the process works. 
Links related to this article: Society for Neuroscience,: www.sfn.org/
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MAP posted-by: Jay Bergstrom