Hashish is a similar drug prepared from the same plant. It differs from marijuana in that it is comprised of only the resin from the plant, whereas marijuana is made up of flowering tops and leaves.
Known in India, Central Asia, and China as early as 3000 BC, marijuana has long been used as both a medicine and an intoxicant. It gained widespread use in the United States in the 1960s and 1970s, becoming the second most popular drug after alcohol, and its popularity continued through the end of the 20th century, particularly among American teens. According to a survey prepared in 1998 by the United States Drug Enforcement Agency, marijuana use among teenagers increased almost 300 percent from 1992 to 1998.
Most countries consider marijuana an illegal substance, but individual countries vary on how they prosecute the use and possession of marijuana. Some countries only impose small fines, while others impose harsher punishment, including imprisonment.
Many users describe two phases of marijuana intoxication: initial stimulation, which includes giddiness and euphoria, followed by sedation and pleasant tranquility. Mood changes are often accompanied by altered perceptions of time and space. Thinking processes become disrupted by fragmentary ideas and memories. Many users report increased appetite, heightened sensory awareness, and general feelings of pleasure.
Negative effects of marijuana use can include confusion, acute panic reactions, anxiety attacks, fear, a sense of helplessness, and loss of self-control. Chronic marijuana users may develop amotivational syndrome characterized by passivity, decreased motivation, and preoccupation with taking drugs. Like alcohol intoxication, marijuana intoxication impairs judgment, comprehension, memory, speech, problem-solving ability, reaction time, and driving skills.
The effects of long-term marijuana use on the intellect have not been established, and there is no evidence that marijuana causes brain damage. Smoking marijuana can damage the lungs, however, and long-term use may increase the risk of lung cancer. Although marijuana is not physically addicting and no physical withdrawal symptoms occur when use is discontinued, psychological dependence develops in some 10 to 20 percent of long-term regular users (see Drug Dependence).