Do some reading: http://www.psychiatry.wustl.edu/Reso...May/Kelley.PDF
Also,
What if you knew that some research indicates that marijuana is not physically addictive?
According to the U.S. Institute of Medicine (IOM), when examining drug addiction, tolerance, dependence, and withdrawal are the characteristics most often assessed to determine whether or not an addiction is indicated. Although some users of marijuana may experience slight tolerance, dependence, or withdrawal associated with use, the IOM argues that this is not evidence that marijuana is addictive. The organization asserts that tolerance and dependence are normal physiological adaptations to repeated use of any substance, including prescription drugs. Safe, appropriate use of many prescribed medications -- for pain, anxiety, hypertension, etc. -- routinely produces some level of tolerance and a slight physiological dependence that is addressed through dosage and may lead to withdrawal symptoms if stopped abruptly, rather than gradually.
The IOM also reported that observable symptoms attributed to marijuana withdrawal are rare and were only identifiable in "unique patient settings... limited to adolescents in treatment facilities for substance abuse problems, and in a research setting where subjects were given marijuana or THC daily." Compared to the withdrawal associated with alcohol or heroin, the marijuana-related symptoms of restlessness, irritability, and sleep disruption are minor. According to reports, the symptoms are not "severe enough to re-initiate use of cannabis." The criteria of tolerance, dependence, and withdrawal, therefore, do not indicate marijuana addiction, assert proponents of marijuana legalization.
Statistics show that fewer than one in 10 marijuana smokers becomes a regular user of the drug and most stop using marijuana after the age of 34. By comparison, reported the National Organization for the Reform of Marijuana Laws (NORML), 15 percent of alcohol consumers and 32 percent of tobacco smokers exhibit symptoms of drug dependence.
Other opponents of marijuana legalization point to the potential relationship between dopamine production in the human brain and marijuana. Dopamine is a neurochemical produced in the central cortex of the brain and is thought to be central to the body's "reward system" which may be the biochemical cause of addiction. The more dopamine produced, the greater the "reward" the body feels. Some marijuana opponents assert that marijuana increases the production of dopamine, but some research has shown that marijuana does not radically affect dopamine production. Researchers also noted that increased dopamine production has been detected in the brains of video game players who were rewarded with cash every time they reached a new level of the game. As Cynthia Cotts wrote in her article "Reefer Madness" in Salon. "Dopamine is released in response to pleasurable activities, which include hitting a home run, listening to Mozart and french-kissing, as well as drinking vodka and snorting cocaine." Therefore, argue marijuana proponents, should marijuana increase dopamine levels, that alone cannot be considered conclusive evidence that marijuana is addictive.
Most experts agree that when the risk of addiction to tobacco, alcohol, and marijuana are compared, there is "strong evidence that marijuana has the least addictive power," wrote Eric Schlosser in The Atlantic Monthly article "Reefer Madness." In fact, argue proponents, during the Nixon administration the federal government, after reviewing existing marijuana studies, concluded that marijuana did not cause physical addiction.
When Dr. Jack Henningfield of the Addiction Research Center and Dr. Neal Benowitz of the University of California ranked heroin, cocaine, nicotine, alcohol, caffeine, and marijuana in terms of their power to induce psychological dependence, nicotine placed first and marijuana ranked last. According to Schlosser, marijuana also came in at last place in terms of inducing a physical tolerance and was deemed least likely to produce signs of withdrawal upon quitting.