Source: The Blade, Toledo, Ohio Contact: 27 June 1997 Studies review marijuana link to hard drugs 'Biochemical pathway' topic of exploration TIMESPOST NEWS SERVICE WASHINGTON In a finding sure to add fuel to the debate over the medical and recreational use of marijuana, two studies released today strongly suggest that pot is a "gateway" drug whose use leads some people to abused socalled hard drugs, such as cocaine and heroin. One study in the journal Science, produced by a team at the Scripps Research Institute in San Diego, demonstrates that the stress and anxiety associated with withdrawal from longterm use of marijuana produces the same biochemical changes associated with withdrawal from harder drugs. This is the "negative reinforcement" that causes a person to take more drugs to alleviate the stress. A second study from Italy emphasizes the opposite side of the coin, positive reinforcement. It demonstrates for the first time that marijuana activates the same pleasure centers in the brain that are targeted by heroin, cocaine, and alcohol, again providing a reason to seek out the drug. "We now have ... a smoking gun a biological mechanism by which this gateway phenomenon could be occurring," said Dr. Herbert Kleber, medical director of the National Center on Addiction and Substance Abuse at Columbia University. The new studies are unlikely to provide the final word in the ongoing dispute about the risks associated with marijuana use, both sides said. But they will provide powerful arguments for those opposed to marijuana use and may change the terms of the debate somewhat, said Scripps neuroscientist George F. Koob. "This blurs the distinction between what is considered a hard and a soft drug," Dr. Koob said, "because they all do the same thing." The backdrop to the argument is government statistics unquestioned by both sides that show that an individual who uses marijuana is 17 times more likely to use cocaine than one who never smoked pot. But the interpretation of these statistics varies dramatically. Marijuana proponents argue there may be a progression because a person who smokes pot has to buy it from an illegal dealer and is thus more likely to be around dealers of other illicit drugs. Alternatively, proponents argue, use of marijuana might be a marker for deviant behavior in general, behavior that is likely to include using other drugs. Opponents, however, argue that marijuana use triggers a biochemical pathway that, in effect, primes the brain for the use of other drugs. The two new papers support this possibility. "I'm not saying [marijuana] is as dangerous a heroin," neuroscientist Gaetano Di Chiara told Science, "but I'm hoping people will approach marijuana far more cautiously than they have before."