at call for more than one or two steps. Some researchers believe that these changes may put a person more at risk of becoming addicted to other drugs, such as cocaine or heroin. Scientists are still learning about the many ways that marijuana could affect the brain. Some frequent, heavy users of marijuana develop a tolerance for it. "Tolerance" means that the user needs larger doses of the drug to get the same desired results that he or she used to get from smaller amounts. There has been much talk about the possible medical use of marijuana. Under U.S. law since 1970, marijuana has been a Division I controlled substance. This means that the drug, at least in its smoked form, has no commonly accepted medical use. THC, the active chemical in marijuana, is manufactured into a pill available by prescription that can be used to treat the nausea and vomiting that occur with certain cancer treatments and to help AIDS patients eat more to keep up their weight. According to scientists, more research needs to be done on marijuana's side effects and potential benefits before it is used medically with any regularity....
