A recent flurry of reports in the UK media focused on a paper in Nature Neuroscience on the addictive properties of the psychoactive component of marijuana. They concerned a report by Steven Goldberg that self-administration behaviour is maintained by the psychoactive ingredient of marijuana, delta-9-tetrahydrocannabinol (THC), in squirrel monkeys. Previous studies that have tried to establish reliable self-administration behaviour in animals with THC have been unsuccessful, indicating that marijuana might have less potential for abuse than other drugs such as heroin and cocaine. The press interest was stimulated by the likely impact of these findings on the polarized debate in the UK media regarding the issue of whether to decriminalize marijuana. So how did the media present the story?

Marijuana “is as addictive as heroin”

A study into the addictiveness of cannabis has concluded that the drug can be as compulsive as cocaine or heroin. The findings will come as a blow to those campaigning for the legalisation of marijuana. The research by Steven Goldberg . . . used a standard test for addictiveness in laboratory animals and found little difference between the effects of cocaine, heroin and cannabis. The Independent

A detail missing from the piece was that self-administration of THC was obtained in monkeys that had previously been trained to self-administer cocaine — a standard test of the addictive properties of psychoactive drugs. Future research will be required to establish whether drug naïve monkeys will also self-administer marijuana at the low doses used in this study. And this may be important in the final analysis of the abuse-potential of marijuana.