Because marijuana seized by federal authorities today is about twice as potent as it was in the 1980s, health officials are taking the drug more seriously.
Although some scientists doubt that marijuana induces real physical dependence, many top drug researchers have concluded otherwise. "There is no question marijuana can be addictive; that argument is over," said Dr. Nora Volkow, director of the National Institute on Drug Abuse. "The most important thing right now is to understand the vulnerability of young, developing brains to these increased concentrations of cannabis."
More than 50 government-funded studies of cannabis are underway, and Volkow has pledged agency funds to investigate areas related to regular marijuana use. These include:
* Effect of cannabis on the young brain. Doctors have little understanding of how regular marijuana use alters the biological development of the brain. Clinicians who treat heavy users say that the earlier a person starts taking the drug, the more quickly a habit takes hold. "The risk of becoming addicted is far higher for a child in junior high than it is for someone who tries it in high school," said Dennis, a researcher at Chestnut Health Systems, a large behavioral care provider in Bloomington. Regular use can also exacerbate symptoms of attention deficit hyperactivity disorder and trigger latent mental disorders, some doctors believe.
* Medications to help break the habit. In recent years, doctors have had some success treating narcotic addiction with drugs such as buprenorphine, which is used for heroin dependence. They have done very little testing of drugs to ease marijuana craving.
* Genetic susceptibility. In a recent study of 198 young people, doctors in New Zealand found that those who reported enjoying their first-time use of marijuana were more likely to develop a habit later on. The researchers said their findings suggested that some people might be genetically vulnerable to addiction. Volkow is encouraging researchers to isolate genes that may contribute to the vulnerability.
Research into the addictive qualities of marijuana has always been controversial. In the 1970s, psychiatrists documented flu-like symptoms in heavy cannabis users withdrawing from the drug. But the symptoms were so mild compared with the agony of withdrawal from heroin, cocaine or nicotine that many doctors dismissed the studies as inconsequential. Others charged that government researchers were attempting to demonize what was a mostly harmless drug.
