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what is marijuana
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. |
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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.
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.
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how is marijuana used?
Cannabis products are
usually smoked. Their effects are felt within minutes, reach their peak in 10
to 30 minutes, and may linger for two or three hours. The effects experienced
often depend upon the experience and expectations of the individual user as
well as the activity of the drug itself. Low doses tend to induce a sense of
well-being and a dreamy state of relaxation, which may be accompanied by a more
vivid sense of sight, smell, taste, and hearing as |
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well as by subtle
alterations in thought formation and expression. This state of intoxication may
not be noticeable to an observer. However, driving, occupational or household
accidents may result from a distortion of time and space relationships and
impaired coordination. Stronger doses intensify reactions. The individual may
experience shifting sensory imagery, rapidly fluctuating emotions, a flight of
fragmentary thoughts with disturbed associations, an altered sense of
self-identity, impaired memory, and a dulling of attention despite an illusion
of heightened insight. High doses may result in image distortion, a loss of
personal identity, and fantasies and hallucinations.
health hazards
Marijuana contains known toxins and cancer-causing chemicals which are
stored in fat cells for as long as several months. Marijuana users experience
the same health problems as tobacco smokers, such as bronchitis, emphysema and
bronchial asthma. Some of the effects of marijuana use also include: an
increased heart rate, dryness of the mouth, reddening if the eyes, impaired
motor skills and concentration, and frequent hunger and an increased desire for
sweets. Extended use increases risk to the lungs and reproductive system, as
well as suppression of the immune system. Occasionally hallucinations,
fantasies and paranoia are reported.
Effects of Marijuana on the Brain
Researchers have found that THC changes the way in which sensory
information gets into and is acted on by the hippocampus. This is a component
of the brain's limbic system that is crucial for learning, memory, and the
integration of sensory experiences with emotions and motivations.
Investigations have shown that neurons in the information processing system of
the hippocampus and the activity of the nerve fibers are suppressed by THC. In
addition, researchers have discovered that learned behaviors, which depend on
the hippocampus, also deteriorate.
Recent research findings also indicate that long-term use of marijuana
produces changes in the brain similar to those seen after long-term use of
other major drugs of abuse.
Effects on the Lungs
Someone who smokes marijuana regularly may have many of the same
respiratory problems that tobacco smokers have. These individuals may have
daily cough and phlegm, symptoms of chronic bronchitis, and more frequent chest
colds. Continuing to smoke marijuana can lead to abnormal functioning of lung
tissue injured or destroyed by marijuana smoke.
Regardless of the THC content, the amount of tar inhaled by marijuana
smokers and the level of carbon monoxide absorbed are three to five times
greater than among tobacco smokers. This may be due to the marijuana users
inhaling more deeply and holding the smoke in the lungs.
Effects on Heart Rate and Blood
Pressure
Recent findings indicate that smoking marijuana while shooting up
cocaine has the potential to cause severe increases in heart rate and blood
pressure. In one study, experienced marijuana and cocaine users were given
marijuana alone, cocaine alone, and then a combination of both. Each drug alone
produced cardiovascular effects; when they were combined, the effects were
greater and lasted longer. The heart rate of the subjects in the study
increased 29 beats per minute with marijuana alone and 32 beats per minute with
cocaine alone. When the drugs were given together, the heart rate increased by
49 beats per minute, and the increased rate persisted for a longer time. The
drugs were given with the subjects sitting quietly. In normal circumstances, an
individual may smoke marijuana and inject cocaine and then do something
physically stressful that may significantly increase risks of overload on the
cardiovascular system.
Effects of Heavy Marijuana Use on Learning and Social
Behavior
A study of college students has shown that critical skills related to
attention, memory, and learning are impaired among people who use marijuana
heavily, even after discontinuing its use for at least 24 hours. Researchers
compared 65 "heavy users," who had smoked marijuana a median of 29 of the past
30 days, and 64 "light users," who had smoked a median of 1 of the past 30
days. After a closely monitored 19- to 24-hour period of abstinence from
marijuana and other illicit drugs and alcohol, the undergraduates were given
several standard tests measuring aspects of attention, memory, and learning.
Compared to the light users, heavy marijuana users made more errors and had
more difficulty sustaining attention, shifting attention to meet the demands of
changes in the environment, and in registering, processing, and using
information. The findings suggest that the greater impairment among heavy users
is likely due to an alteration of brain activity produced by
marijuana.
Longitudinal research on marijuana use among young people below
college age indicates those who used have lower achievement than the non-users,
more acceptance of deviant behavior, more delinquent behavior and aggression,
greater rebelliousness, poorer relationships with parents, and more
associations with delinquent and drug-using friends.
Research also shows more anger and more regressive behavior (thumb
sucking, temper tantrums) in toddlers whose parents use marijuana than among
the toddlers of non-using parents.
Effects on Pregnancy
Any drug of abuse can affect a mother's health during pregnancy, and
this is a time when she should take special care of herself. Drugs of abuse may
interfere with proper nutrition and rest, which can affect good functioning of
the immune system. Some studies have found that babies born to mothers who used
marijuana during pregnancy were smaller than those born to mothers who did not
use the drug. In general, smaller babies are more likely to develop health
problems.
A nursing mother who uses marijuana passes some of the THC to the baby
in her breast milk. Research indicates that the use of marijuana by a mother
during the first month of breast-feeding can impair the infant's motor
development (control of muscle movement).
Addictive Potential
A drug is addicting if it causes compulsive, often uncontrollable drug
craving, seeking, and use, even in the face of negative health and social
consequences. Marijuana meets this criterion. More than 120,000 people seek
treatment per year for their primary marijuana addiction. In addition, animal
studies suggest marijuana causes physical dependence, and some people report
withdrawal symptoms.
extent of
use
National Survey on Drug Use and
Health
Based on SAMHSA's
2003 National Survey on Drug Use and Health, 3.1 million persons aged 12 or
older used marijuana daily, that is, on 300 or more days in the past year.
Between 2002 and 2003, the number of 12 to 17 year olds reporting daily use of
marijuana decreased from 358,000 to 282,000; while there were no changes in the
number of daily marijuana users among 18-25 year olds or adults age 26 or
older.
An estimated 39.2% of daily marijuana users were dependent on or
abused marijuana compared with 13.5% of less-than-daily marijuana users.
Daily marijuana users (63.3%) were more likely than less-than-daily marijuana
users (38.8%) or non marijuana users (4.6%) to use another illicit drug. Daily
marijuana users also were more likely to be current cigarette smokers and heavy
drinkers.
More than half of daily marijuana users (53.3%) reported dependence
on or abuse of alcohol or an an illicit drug compared with those who were
less-than-daily users (36.5%) and nonusers (5.6%).
The percentage of youths
aged 12 to 17 who had ever used marijuana declined slightly from 2001 to 2002
(21.9 to 20.6 percent). Among young adults aged 18 to 25, the rate increased
slightly from 53.0 percent in 2001 to 53.8 percent in 2002 (Figure 5.1).
In
1965 and 1966, only 1.8 percent of youths had ever used marijuana. Beginning in
1967, use increased until it reached a peak at 19.6 percent in 1979. A period
of decline followed until 1991, when the rate was 11.5 percent, after which the
trend reversed, reaching a peak at 21.9 percent in 2001.
The percentage of young
adults aged 18 to 25 who had ever used marijuana was 5.1 percent in 1965, but
increased steadily to 54.4 percent in 1982. Although the rate for young adults
declined somewhat from 1982 to 1993, it did not drop below 43 percent and
actually increased to 53.8 percent by 2002.
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