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/