Marijuana Information
 Marijuana
is a green or gray mixture of dried, shredded flowers and leaves of the
hemp plant Cannabis sativa. There are over 200 slang terms for marijuana
including "pot," "herb," "weed,"
"boom," "Mary Jane," "gangster," and
"chronic." It is usually smoked as a cigarette (called a joint
or a nail) or in a pipe or bong. In recent years, it has appeared in
blunts. These are cigars that have been emptied of tobacco and re-filled
with marijuana, often in combination with another drug, such as crack.
Some users also mix marijuana into foods or use it to brew tea.
Marijuana's active chemical ingredient
The main active chemical in marijuana is THC
(delta-9-tetrahydrocannabinol). In 1988, it was discovered that the
membranes of certain nerve cells contain protein receptors that bind
THC. Once securely in place, THC kicks off a series of cellular
reactions that ultimately lead to the high that users experience when
they smoke marijuana. The short-term effects of marijuana use include
problems with memory and learning; distorted perception; difficulty in
thinking and problem solving; loss of coordination; and increased heart
rate, anxiety, and panic attacks.
Marijuana effects may be hereditary
Scientists
have found that whether an individual has positive or negative
sensations after smoking marijuana can be influenced by heredity. A
recent study demonstrated that identical male twins were more likely
than nonidentical male twins to report similar responses to marijuana
use, indicating a genetic basis for their sensations. Identical twins
share all of their genes, and fraternal twins share about half.
Environmental factors such as the availability of marijuana,
expectations about how the drug would affect them, the influence of
friends and social contacts, and other factors that would be different
even for identical twins also were found to have an important effect;
however, it also was discovered that the twins' shared or family
environment before age 18 had no detectable influence on their response
to marijuana.
Extent of Marijuana Use
Marijuana and the Monitoring the Future Study (MTF)
The NIDA-funded MTF provides an annual assessment of drug use among
12th, 10th, and 8th grade students and young adults nationwide. After
decreasing for over a decade, marijuana use among students began to
increase in the early 1990s. From 1996 to 1997, use of marijuana at
least once (lifetime use) increased among 12th and 10th graders,
continuing the trend seen in recent years. The seniors' rate of lifetime
marijuana use is higher than any year since 1987, but all rates remain
well below those seen in the late 1970s and early 1980s.
Past year and past month marijuana use did not change significantly
from 1996 to 1997 in any of the three grades, suggesting the sharp
increases of recent years may be slowing. Daily marijuana use in the
past month increased among 12th graders, but decreased among 8th
graders; this pattern of increases among older students and stable or
declining rates among younger students was found with several indicators
in the 1997 MTF.
Percentage of 8th-Graders Who Have Used Marijuana: Monitoring the
Future Study
Click here to view tabular information
Percentage of 12th-Graders Who Have Used Marijuana: Monitoring
the Future Study
Click here to view tabular information
Marijuana and the Community Epidemiology Work Group (CEWG)
The resurgence in marijuana use continues, especially among
adolescents, with rates of emergency department mentions of marijuana
increasing from 1994 to 1995 in 10 cities, the percentage of treatment
admissions increasing in 13 areas, and the National Institute of
Justice's Drug Use Forecasting (DUF) percentages increasing among
juvenile arrests at numerous sites. In several cities, such as
Minneapolis/St. Paul, increasing treatment figures have been
particularly notable among juveniles. Two factors may be contributing to
the dramatic leap in adverse consequences: higher potency and the use of
marijuana mixed with or in combination with other dangerous drugs.
Marijuana and the National Household Survey on Drug Abuse (NHSDA)
Marijuana remains the most commonly used illicit drug in the
United States. There were an estimated 2.4 million people who started
using marijuana in 1995. According to data from the 1996 NHSDA, more
than 68.6 million Americans (32 percent) 12 years of age and older have
tried marijuana at least once in their lifetimes, and almost 18.4
million (8.6 percent) had used marijuana in the past year. In 1985, 56.5
million Americans (29.4 percent) had tried marijuana at least once in
their lifetimes, and 26.1 million (13.6 percent) had used marijuana
within the past year.
Information on this page courtesy of National
Institute on Drug Abuse.
NOTE: See additional Marijuana information page links in the Related
Links column at the right.
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