After finishing this chapter, students should be able to understand:
Cannabis has a rich history relating both to its medicinal use and to its recreational uses.
Marijuana became famous as the "Assassin of Youth" in the 1930s and was outlawed in 1937.
Cannabis contains many active chemicals, but the most active is delta-9-THC.
THC is absorbed rapidly by smoking but slowly and incompletely when taken by mouth.
THC has a long half-life of elimination, and its metabolites can be found in the body for up to several weeks after THC enters the body.
Selective THC receptors exist in brain tissue, leading to the discovery of a naturally occurring brain cannabinoid, anandamide.
Marijuana causes an increase in the heart rate and reddening of the eyes as its main physiological effects.
Psychologically, THC has some sedative properties, produces some analgesia, and at high doses can produce hallucinations.
In recreational use, some of marijuana's most important behavioral effects probably relate to its impairment of memory.
Marijuana is useful in the treatment of glaucoma, the reduction of nausea in patients undergoing cancer chemotherapy, and the increase of appetite in AIDS patients. A legal form of THC is available by prescription.
Although strong behavioral dependence is not common, it does occur in some individuals.
Marijuana can impair driving, and there is evidence that smoking marijuana leads to an increased frequency of accidents.
Most experts agree that chronic smoking of marijuana impairs lung function somewhat and probably increases the risk of lung cancer.
Long-standing concerns about marijuana-induced brain damage have received some limited support from animal studies.
