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Is Marijuana Addictive?

There's a lot of science on the books on the question of marijuana's addictive properties, but is the issue too politicized to get any clear answers?

 Is marijuana addictive?

The National Institute on Drug Abuse (NIDA) says it is. According to its “Marijuana Abuse” research report, “Long-term marijuana use can lead to addiction; that is, people have difficulty controlling their drug use and cannot stop even though it interferes with many aspects of their lives."

The Office of National Drug Control Policy’s  abovetheinfluence.com Web site is blunter. “Marijuana is addictive, with more teens in treatment with a primary diagnosis of marijuana dependence than for all other illicit drugs combined,” it declares. 

Sentiment among marijuana users and advocates is the exact opposite. While a minority of pot-smokers get high so frequently it impairs their functioning, the vast majority insist they can do it occasionally or regularly without problems.

The word “addiction” conjures up the stereotype of a heroin junkie, willing to lie, manipulate, steal, and perform cut-rate oral sex in order to avoid suffering the withdrawal—nausea, diarrhea and flu-like distress—that comes after they go without the drug for several hours. Cocaine, however, does not produce a similar physical withdrawal. So over the last generation, the concept has evolved to a more complex, subjective model. 

NIDA now calls addiction “a complex illness characterized by intense and, at times, uncontrollable drug craving, along with compulsive drug seeking and use that persist even in the face of devastating consequences.” The DSM-IV, the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders, lists the criteria for drug “dependence” as tolerance, withdrawal, continuing to use despite negative psychological or physical consequences, using more than you want to, unsuccessful attempts to cut down or quit, excessive time spent procuring the drug, and withdrawal from social, work or family obligations.

Some marijuana users reach that point. “Marijuana controls our lives!” the 12-step recovery group Marijuana Anonymous exclaims on its Web site. “Our lives, our thinking, and our desires center around marijuana—scoring it, dealing it, and finding ways to stay high.”

The vast majority don’t reach that point. Among the commonly used drugs, pot is the least likely to cause dependence. The estimate most often cited, based on a NIDA-supported survey from the early 1990s, is that 9 percent of people who use marijuana will develop dependence at some point in their lives, compared with 15 percent for alcohol, 17 percent for cocaine, 23 percent for heroin, and 32 percent for tobacco. 

Mitch Earleywine, author of Understanding Marijuana: A New Look at the Scientific Evidence and a psychology professor at the University at Albany in New York, disputes that 9 percent figure. If you focus on genuine problems, “instead of some manufactured diagnosis,” he says, maybe 4 to 8 percent of regular marijuana users have problems.

The two main arguments that cannabis is addictive are the number of people admitted to drug-treatment programs primarily for marijuana use and research indicating that chronic use may cause a withdrawal syndrome.

The proportion of people admitted to rehab primarily for marijuana use increased significantly from 1999 to 2009, from 13.5 percent of admissions to 18 percent of the nearly 2 million tracked by federal Substance Abuse and Mental Health Services Administration in its Treatment Episode Data Set. More than half of teenagers in rehab were there for pot. 

However, according to SAMHSA figures from 2009, 56 percent of the more than 350,000 people admitted to drug treatment for marijuana were referred by the criminal-justice system, such as after an arrest or probation violation. Only 15 percent were “self-referred,” seeking rehab voluntarily. For the 282,000 heroin admissions, the proportions were exactly the opposite: 55 percent came in on their own, and only 15 percent were referred by legal authorities. For crack, 36 percent of the about 130,000 admissions were self-referred, and 29 percent sent over by the criminal-justice system.

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