MARIJUANA COULD HELP COCAINE ADDICTS KICK HABIT

Smoking marijuana could help prevent recovering cocaine addicts relapsing,
research on rats suggests. Dutch and US scientists deprived
cocaine-addicted rats of the drug for 14 days and then exposed them to
environmental cues associated with their drug-taking. Such cues often
trigger relapse in recovering human addicts.

When the rats were also injected with a synthetic drug that blocks
cannabinoid receptors - the same receptors targeted by the active compounds
in marijuana - they were much less likely to seek an injection of cocaine.

"We found that in the rats exposed to environmental cues associated with
cocaine injection in the past, or to cocaine itself, the likelihood of
relapse was reduced by 50 to 60 per cent," says Taco de Vries, who led the
research at Vrije University in Amsterdam and the US National Institute on
Drug Abuse. Unpublished studies by the team on heroin-addicted rats have
shown similar results, he told New Scientist.

Drugs to help prevent relapse in cocaine users are desperately needed, says
de Vries. "Right now there is not much available. You can give
anti-depressants to help with the symptoms of withdrawal but they don't
seem to work very well."

Alcohol And Smoking

Danielle Piomelli of the University of California, Irvine agrees. "The
finding that blockade of cannabinoid receptors prevents cue-mediated
relapses to cocaine seeking is of obvious therapeutic significance," she
writes in a commentary on the research in the journal Nature Medicine.

It is not clear exactly how blocking cannabinoid receptors should reduce
the likelihood of relapse, says the team. But the cannabinoid system is
closely linked to the dopamine system, the body's "reward" centre.

It is possible that blocking cannabinoid receptors could help people trying
to give up alcohol, as well as heroin, cocaine and smoking, says deVries.

However, the cannabinoid system does not seem to mediate the brain's
response to stress triggers during withdrawal, which can also cause
relapses in drug-taking. "As with other chronic diseases, it is reasonable
to expect that treatment of drug craving and relapse will involve the use
of more than one drug," writes Piomelli.

Journal Reference: Nature Medicine (vol 7, p 1151)