Pubdate: Fri, 11 May 2001
Source: Reuters (Wire)
Copyright: 2001 Reuters Limited
Details: http://www.mapinc.org/media/364
Author: Will Dunham
Bookmark: http://www.mapinc.org/coke.htm (Cocaine)

STUDY REVEALS NEW APPROACH TO STOP COCAINE RELAPSE

WASHINGTON (Reuters) - The brain stores the craving for cocaine in a 
different place than it registers the high caused by the drug, researchers 
said on Thursday in a finding that points to a promising new approach for 
treating addicts.

Scientists at the Albert Einstein College of Medicine in New York used rats 
to study a vexing problem -- how to prevent cocaine addicts who seem to 
have kicked the habit from relapsing. The findings suggest that a solution 
may be blocking a brain chemical that largely has been overlooked in 
addiction research.

``If you listen to patients' stories, one thing that you hear over and over 
again are the intense cravings that are very, very hard to suppress and 
that eventually lead to the relapse,'' Dr. Stanislav Vorel, who led the 
research, said in an interview.

``So a major question is -- what are these cravings, how are they 
triggered, how can we prevent them or how can patients learn to cope with 
them?'' he added.

The researchers hooked the rats on cocaine by delivering intravenous doses 
when the rodents pushed a lever in their cages. The researchers then made 
the rats quit cold turkey by replacing the cocaine with a saline solution. 
After a week, the animals stopped pressing the lever seeking a cocaine fix.

The researchers then sought to trigger a relapse by electrically 
stimulating two parts of the brain.

One was the ``reward'' or ``liking'' center that registers the high from 
using the drug -- a brain pathway that involves a chemical called dopamine.

The other was in the hippocampus region of the brain, which is associated 
with memory and involves glutamate, an entirely different brain chemical. 
This region appears to register the memory of a drug's effects and the 
craving for it, Vorel said.

Stimulating the hippocampus caused an intense craving for cocaine, the 
study found. The rats repeatedly pressed the lever that previously had 
delivered cocaine.

The researchers then demonstrated that a chemical that blocks glutamate 
prevented the relapse even in rats whose hippocampus region had been 
electrically stimulated.

The study was published in the journal Science.

In separate research that has not yet been published, Vorel said his 
laboratory found that electrical stimulation of the almond-shaped brain 
structure related to memory, the amygdala, also caused relapse.

NEW ADDICTION TREATMENT APPROACH

Glutamate is a neurotransmitter involved in essential brain functions such 
as learning and memory. Vorel said developing a drug targeting glutamate 
may be able to help a cocaine addict quit the drug for good.

The development of drugs to treat cocaine addiction has consistently 
focused on dopamine, which is connected to the brain's ``liking'' region 
rather than the ``wanting'' produced by stimulating the memory area, said 
Vorel.

But Vorel's new research shows that glutamate could be a better target for 
anti-craving medication, he added.

Vorel said relapse is the single biggest obstacle to successful cocaine 
addiction treatment.

``I believe that an addicted brain is different than a normal brain, and it 
becomes for a very, very long time -- if not forever -- sensitive to 
triggers of relapse,'' Vorel said.

``Patients will do well for long or short periods of time. But even years 
after their last cocaine use, they're still vulnerable to relapse.''
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