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National Institute on Drug Abuse
Revised November, 1998

A Letter to Parents

Marijuana is the illegal drug most often used in this country. Since 1991, lifetime marijuana use has doubled among 8th- and 10th-grade students, and increased by a third among high school seniors (19). Our research shows that accompanying this upward pattern of use is a significant erosion in antidrug perceptions and knowledge among young people today. As the number of young people who use marijuana has increased, the number who view the drug as harmful has decreased. Among high school seniors surveyed in 1997, current marijuana use has increased by about 72 percent since 1991. The proportion of those seniors who believe regular use of marijuana is harmful has dropped by about 26 percent since 1991(19).

These changes in perception and knowledge may be due to a decrease in antidrug messages in the media, an increase in prodrug messages through the pop culture, and a lack of awareness among parents about this resurgence in drug use - most thinking, perhaps, that this threat to their children had diminished.

In December 1994, HHS Secretary Donna E. Shalala, Ph.D., called for an Initiative to alert the public - particularly parents - to the rise in marijuana use, its potential health consequences to young people, and the need for parents to take action to prevent the return of a full-blown epidemic of teenage drug use.

Because many parents of this generation of teenagers experimented with marijuana when they were in college, they often find it difficult to talk about marijuana use with their children and to set strict ground rules against drug use. But marijuana use today starts at a younger age - and more potent forms of the drug are available to these young children. Parents need to recognize that marijuana use is a serious threat - and they need to tell their children not to use it.

We at the National Institute on Drug Abuse (NIDA) are pleased to offer these two short booklets, Marijuana: Facts for Teens and Marijuana: Facts Parents Need to Know, for parents and their children to review the scientific facts about marijuana. While it is best to talk about drugs when children are young, it is never too late to talk about the dangers of drug use.

Talking to our children about drug abuse is not always easy, but it is very important. I hope these booklets can help.

Alan I. Leshner, Ph.D.
Director
National Institute on Drug Abuse

Q: What is Marijuana? Are there different kinds?

A: Marijuana is a green, brown, or gray mixture of dried, shredded leaves, stems, seeds, and flowers of the hemp plant (Cannabis sativa). Before the 1960s, many Americans had never heard of marijuana, but today it is the most often used illegal drug in this country.

Cannabis is a term that refers to marijuana and other drugs made from the same plant. Strong forms of cannabis include sinse-milla (sin-seh-me-yah), hashish ("hash" for short), and hash oil.

All forms of cannabis are mind-altering (psychoactive) drugs; they all contain THC (delta-9-tetrahydrocannabinol), the main active chemical in marijuana. They also contain more than 400 other chemicals.

Marijuana's effect on the user depends on the strength or potency of the THC it contains (6). THC potency has increased since the 1970s but has been about the same since the mid-1980s. The strength of the drug is measured by the average amount of THC in test samples confiscated by law enforcement agencies.

• Most ordinary marijuana has an average of 3 percent THC.
• Sinsemilla (made from just the buds and flowering tops of female plants) has an average of 7.5 percent THC, with a range as high as 24 percent.
• Hashish (the sticky resin from the female plant flowers) has an average of 3.6 percent, with a range as high as 28 percent.
• Hash oil, a tar-like liquid distilled from hashish, has an average of 16 percent, with a range as high as 43 percent.

Q: What are the current slang terms for marijuana?

A: There are many different names for marijuana. Slang terms for drugs change quickly, and they vary from one part of the country to another. They may even differ across sections of a large city.

Terms from years ago, such as pot, herb, grass, weed, Mary Jane, and reefer, are still used. You might also hear the names Aunt Mary, skunk, boom, gangster, kif, or ganja.

There are also street names for different strains or "brands" of marijuana, such as "Texas tea," "Maui wowie," and "Chronic." A recent book of American slang lists more than 200 terms for various kinds of marijuana.

Q: How is marijuana used?

A: Most users roll loose marijuana into a cigarette (called a joint or a nail) or smoke it in a pipe. One well-known type of water pipe is the bong. Some users mix marijuana into foods or use it to brew a tea. Another method is to slice open a cigar and replace the tobacco with marijuana, making what's called a blunt. When the blunt is smoked with a 40 oz. bottle of malt liquor, it is called a "B-40."

Lately, marijuana cigarettes or blunts often include crack cocaine, a combination known by various street names, such as "primos" or "woolies." Joints and blunts often are dipped in PCP and are called "happy sticks," "wicky sticks," "love boat," or "tical."

Q: How many people smoke marijuana? At what age do children generally start?

A: A recent government survey tells us:

• Marijuana is the most frequently used illegal drug in the United States. Nearly 69 million Americans over the age of 12 have tried marijuana at least once.
• About 10 million had used the drug in the month before the survey.
• Among teens 12 to 17, the average age of first trying marijuana was 14 years.(18)

A yearly survey of students in grades 8 through 12 shows that 23 percent of 8th-graders have tried marijuana at least once, and by 10th grade, 21 percent are "current" users (that is, used within the past month)(19). Among 12th-graders, nearly 50 percent have tried marijuana/hash at least once, and about 24 percent were current users(19).

Other researchers have found that use of marijuana and other drugs usually peaks in the late teens and early twenties, then declines in later years.

Q: Why do young people use marijuana?

A: Children and young teens start using marijuana for many reasons. Curiosity and the desire to fit into a social group are common reasons. Certainly, youngsters who have already begun to smoke cigarettes and/or use alcohol are at high risk for marijuana use.

Also, our research suggests that the use of alcohol and drugs by other family members plays a strong role in whether children start using drugs. Parents, grandparents, and older brothers and sisters in the home are models for children to follow.

Some young people who take drugs do not get along with their parents. Some have a network of friends who use drugs and urge them to do the same (peer pressure). All aspects of a child's environment - home, school, neighborhood - help to determine whether the child will try drugs.

Children who become more heavily involved with marijuana can become dependent, and that is their prime reason for using the drug. Others mention psychological coping as a reason for their use - to deal with anxiety, anger, depression, boredom, and so forth. But marijuana use is not an effective method for coping with life's problems, and staying high can be a way of simply not dealing with the problems and challenges of growing up.

Researchers have found that children and teens (both male and female) who are physically and sexually abused are at greater risk than other young people of using marijuana and other drugs and of beginning drug use at an early age.(7)

Q: Does using marijuana lead to other drugs?

A: Long-term studies of high school students and their patterns of drug use show that very few young people use other drugs without first trying marijuana. The risk of using cocaine has been estimated to be more than 104 times greater for those who have tried marijuana than for those who have never tried it.(9) Although there are no definitive studies on the factors associated with the movement from marijuana use to use of other drugs, growing evidence shows that a combination of biological, social, and psychological factors are involved.

Marijuana affects the brain in some of the same ways that other drugs do. Researchers are examining the possibility that long-term marijuana use may create changes in the brain that make a person more at risk of becoming addicted to other drugs, such as alcohol or cocaine.(16) While not all young people who use marijuana go on to use other drugs, further research is needed to determine who will be at greatest risk.

Q:What are the effects of marijuana?

A: The effects of marijuana on each person depend on the

• type of cannabis and how much THC it contains;
• way the drug is taken (by smoking or eating);
• experience and expectations of the user;
• setting where the drug is used; and
• whether drinking or other drug use is also going on.

Some people feel nothing at all when they first try marijuana. Others may feel high (intoxicated and/or euphoric).

It's common for marijuana users to become engrossed with ordinary sights, sounds, or tastes, and trivial events may seem extremely interesting or funny. Time seems to pass very slowly, so minutes feel like hours. Sometimes the drug causes users to feel thirsty and very hungry-an effect called "the munchies."

Q: What happens after a person smokes marijuana?

A: Within a few minutes of inhaling marijuana smoke, the user will likely feel, along with intoxication, a dry mouth, rapid heartbeat, some loss of coordination and poor sense of balance, and slower reaction time. Blood vessels in the eye expand, so the user's eyes look red.

For some people, marijuana raises blood pressure slightly and can double the normal heart rate. This effect can be greater when other drugs are mixed with marijuana; but users do not always know when that happens.

As the immediate effects fade, usually after 2 to 3 hours, the user may become sleepy.

Q: How long does marijuana stay in the user's body?

A: THC in marijuana is readily absorbed by fatty tissues in various organs. Generally, traces (metabolites) of THC can be detected by standard urine testing methods several days after a smoking session. However, in heavy, chronic users, traces can sometimes be detected for weeks after they have stopped using marijuana.

Q: Can a user have a bad reaction?

A: Yes. Some users, especially someone new to the drug or in a strange setting, may suffer acute anxiety and have paranoid thoughts. This is more likely to happen with high doses of THC. These scary feelings will fade as the drug's effects wear off.

In rare cases, a user who has taken a very high dose of the drug can have severe psychotic symptoms and need emergency medical treatment.

Other kinds of bad reactions can occur when marijuana is mixed with other drugs, such as PCP or cocaine.

Q: How is marijuana harmful?

A: Marijuana can be harmful in a number of ways, through both immediate effects and damage to health over time.

Marijuana hinders the user's short-term memory (memory for recent events), and he or she may have trouble handling complex tasks. With the use of more potent varieties of marijuana, even simple tasks can be difficult.

Because of the drug's effects on perceptions and reaction time, users could be involved in auto crashes. Drug users also may become involved in risky sexual behavior. There is a strong link between drug use and unsafe sex and the spread of HIV, the virus that causes AIDS.

Under the influence of marijuana, students may find it hard to study and learn.(14) Young athletes could find their performance is off; timing, movements, and coordination are all affected by THC.

Some of the more long-range effects of marijuana use are described later in this document.

Q: How does marijuana affect driving?

A: Marijuana affects many skills required for safe driving: alertness, the ability to concentrate, coordination, and reaction time. These effects can last up to 24 hours after smoking marijuana. Marijuana use can make it difficult to judge distances and react to signals and sounds on the road.

There are data showing that marijuana can play a role in crashes. When users combine marijuana with alcohol, as they often do, the hazards of driving can be more severe than with either drug alone.

A study of patients in a shock-trauma unit who had been in traffic accidents revealed that 15 percent of those who had been driving a car or motorcycle had been smoking marijuana, and another 17 percent had both THC and alcohol in their blood. (17)

In one study conducted in Memphis, TN, researchers found that, of 150 reckless drivers who were tested for drugs at the arrest scene, 33 percent tested positive for marijuana, and 12 percent tested positive for both marijuana and cocaine.(2) Data also show that while smoking marijuana, people show the same lack of coordination on standard "drunk driver" tests as do people who have had too much to drink.(11)

Q: What are the long-term effects of marijuana?

A: While all of the long-term effects of marijuana use are not yet known, there are studies showing serious health concerns. For example, a group of scientists in California examined the health status of 450 daily smokers of marijuana but not tobacco. They found that the marijuana smokers had more sick days and more doctor visits for respiratory problems and other types of illness than did a similar group who did not smoke either substance.(13)

Findings so far show that the regular use of marijuana or THC may play a role in cancer and problems in the respiratory, immune, and reproductive systems.

Cancer
It is hard to find out whether marijuana alone causes cancer because many people who smoke marijuana also smoke cigarettes and use other drugs. Marijuana smoke contains some of the same cancer-causing compounds as tobacco, sometimes in higher concentrations. Studies show that someone who smokes five joints per week may be taking in as many cancer-causing chemicals as someone who smokes a full pack of cigarettes every day.(20)

Tobacco smoke and marijuana smoke may work together to change the tissues lining the respiratory tract. Marijuana smoking could contribute to early development of head and neck cancer in some people.

Immune system
Our immune system protects the body from many agents that cause disease. It is not certain whether marijuana damages the immune system of people. But both animal and human studies have shown that marijuana impairs the ability of T-cells in the lungs' immune defense system to fight off some infections. People with HIV and others whose immune system is impaired should avoid marijuana use.

Lungs and airways
People who smoke marijuana often develop the same kinds of breathing problems that cigarette smokers have. They have symptoms of daily cough and phlegm (chronic bronchitis) and more frequent chest colds. They are also at greater risk of getting lung infections such as pneumonia. Continued marijuana smoking can lead to abnormal function of the lungs and airways. Scientists have found signs of lung tissue injured or destroyed by marijuana smoke.

Q: What about pregnancy: Will smoking marijuana hurt the baby?

A: Doctors advise pregnant women not to use any drugs because they might harm the growing fetus. One animal study has linked marijuana use to loss of the fetus very early in pregnancy.

Some scientific studies have found that babies born to marijuana users were shorter, weighed less, and had smaller head sizes than those born to mothers who did not use the drug. Smaller babies are more likely to develop health problems. Other scientists have found effects of marijuana that resemble the features of fetal alcohol syndrome. There are also research findings that show nervous system problems in children of mothers who smoked marijuana.(3)

Researchers are not certain whether a newborn baby's health problems, if they are caused by marijuana, will continue as the child grows. Preliminary research shows that children born to mothers who used marijuana regularly during pregnancy may have trouble concentrating.

Q: What happens if a nursing mother uses marijuana?

A: When a nursing mother uses marijuana, some of the THC is passed to the baby in her breast milk. This is a matter for concern, since the THC in the mother's milk is much more concentrated than that in the mother's blood. One study has shown that the use of marijuana by a mother during the first month of breastfeeding can impair the infant's motor development (control of muscle movement).(15)

Q: How does marijuana affect the brain?

A: THC affects the nerve cells in the part of the brain where memories are formed. This makes it hard for the user to recall recent events (such as what happened a few minutes ago). It is hard to learn while high - a working short-term memory is required for learning and performing tasks that call for more than one or two steps.

Among a group of long-time heavy marijuana users in Costa Rica, researchers found that the people had great trouble when asked to recall a short list of words (a standard test of memory). People in that study group also found it very hard to focus their attention on the tests given to them.(5)

Smoking marijuana causes some changes in the brain that are like those caused by cocaine, heroin, and alcohol. Some researchers believe that these changes may put a person more at risk of becoming addicted to other drugs, such as cocaine or heroin.(16)

It may be that marijuana kills brain cells. In laboratory research, scientists found that high doses of THC given to young rats caused a loss of brain cells such as that seen with aging. At 11 or 12 months of age (about half their normal life span), the rats' brains looked like those of animals in old age. It is not known whether a similar effect occurs in humans.(10)

Researchers are still learning about the many ways that marijuana could affect the brain.

Q: Can the drug cause mental illness?

A: Scientists do not yet know how the use of marijuana relates to mental illness. Some researchers in Sweden report that regular, long-term intake of THC (from cannabis) can increase the risk of developing certain mental diseases, such as schizophrenia. (1)

Still others maintain that regular marijuana use can lead to chronic anxiety, personality disturbances, and depression.

Q: Do marijuana users lose their motivation?

A: Some frequent, long-term marijuana users show signs of a lack of motivation (amotivational syndrome). Their problems include not caring about what happens in their lives, no desire to work regularly, fatigue, and a lack of concern about how they look. As a result of these symptoms, some users tend to perform poorly in school or at work. Scientists are still studying these problems.

Q: Can a person become addicted to marijuana?

A: Yes. While not everyone who uses marijuana becomes addicted, when a user begins to seek out and take the drug compulsively, that person is said to be dependent on the drug or addicted to it. In 1995, 165,000 people entering drug treatment programs reported marijuana as their primary drug of abuse, showing they needed help to stop using.(12)

Some heavy users of marijuana show signs of dependence because when they do not use the drug, they develop withdrawal symptoms. Some subjects in an experiment on marijuana withdrawal had symptoms, such as restlessness, loss of appetite, trouble with sleeping, weight loss, and shaky hands.

According to one study, marijuana use by teenagers who have prior serious antisocial problems can quickly lead to dependence on the drug. That study also found that, for troubled teenagers using tobacco, alcohol, and marijuana, progression from their first use of marijuana to regular use was about as rapid as their progression to regular tobacco use, and more rapid than the progression to regular use of alcohol.(4)

Q: What is "tolerance" for marijuana?

A: "Tolerance" means that the user needs increasingly larger doses of the drug to get the same desired results that he or she previously got from smaller amounts. Some frequent, heavy users of marijuana may develop tolerance for it.

Q: Are there treatments to help marijuana users?

A: Up until a few years ago, it was hard to find treatment programs specifically for marijuana users. Treatments for marijuana dependence were much the same as therapies for other drug abuse problems. These include detoxification, behavioral therapies, and regular attendance at meetings of support groups, such as Narcotics Anonymous.

Recently, researchers have been testing different ways to attract marijuana users to treatment and help them abstain from drug use. There are currently no medications for treating marijuana dependence. Treatment programs focus on counseling and group support systems. From these studies, drug treatment professionals are learning what characteristics of users are predictors of success in treatment and which approaches to treatment can be most helpful.

Further progress in treatment to help marijuana users includes a number of programs set up to help adolescents in particular. Some of these programs are in university research centers, where most of the young clients report marijuana as their drug of choice. Others are in independent adolescent treatment facilities. Family physicians are also a good source for information and help in dealing with adolescents' marijuana problems.

Q: Can marijuana be used as medicine?

A: There has been much debate in the media about the possible medical use of marijuana. Under U.S. law since 1970, marijuana has been a Schedule I controlled substance. This means that the drug, at least in its smoked form, has no commonly accepted medical use.

In considering possible medical uses of marijuana, it is important to distinguish between whole marijuana and pure THC or other specific chemicals derived from cannabis. Whole marijuana contains hundreds of chemicals, some of which are clearly harmful to health.

THC, manufactured into a pill that is taken by mouth, not smoked, can be used for treating the nausea and vomiting that go along with certain cancer treatments and is available by prescription. Another chemical related to THC (nabilone) has also been approved by the Food and Drug Administration for treating cancer patients who suffer nausea. The oral THC is also used to help AIDS patients eat more to keep up their weight.

Scientists are studying whether marijuana, THC, and related chemicals in marijuana (called cannabinoids) may have other medical uses. According to scientists, more research needs to be done on marijuana's side effects and potential benefits before it can be recommended for medical use.

Q: How can I prevent my child from getting involved with marijuana?

A: There is no magic bullet for preventing teenage drug use. But parents can be influential by talking to their children about the dangers of using marijuana and other drugs, and remain actively engaged in their children's lives. Even after teenage children enter high school, parents can stay involved in schoolwork, recreation, and social activities with their children's friends. Research shows that appropriate parental monitoring can reduce future drug use, even among those adolescents who may be prone to marijuana use, such as those who are rebellious, cannot control their emotions, and experience internal distress. To address the issue of drug abuse in your area, it is important to get involved in drug abuse prevention programs in your community or your child's school. Find out what prevention programs you and your children can participate in together.

Talking to your children about marijuana

As this booklet has shown, marijuana is clearly a dangerous drug which poses a particular threat to the health and well-being of children and adolescents at a critical point in their lives - when they are growing, learning, maturing, and laying the foundation for their adult years. As a parent, your children look to you for help and guidance in working out problems and in making decisions, including the decision not to use drugs. As a role model, your decision to not use marijuana and other illegal drugs will reinforce your message to your children.

There are numerous resources, many right in your own community, where you can obtain information so that you can talk to your children about drugs. To find these resources, you can consult your local library, school, or community service organization.

The National Clearinghouse for Alcohol and Drug Information (NCADI) offers an extensive collection of publications, videotapes, and educational materials to help parents talk to their children about drug use. For more information on marijuana and other drugs, contact:

National Clearinghouse on Alcohol and Drug Information,
P.O. Box 2345,
Rockville, MD 20847
1-800-729-6686
(TDD Number 1-800-487-4889)

Resources

Center for Substance Abuse Prevention, U.S. Department of Health and Human Services. Keeping Youth Drug Free: A Guide for Parents, Grandparents, Elders, Mentors, and Others Caregivers. NCADI Stock No. PHD711, 1996.

Harrison, P.A.; Fullerson, J.A.; and Beebe, T.J. Multiple substance use among adolescent physical and sexual abuse victims. Child Abuse and Neglect 21(6):529-539, 1997.

Hermes, W.J., and Galperin, A. The Encyclopedia of Psychoactive Drugs: Marijuana, Its Effects on Mind and Body. Chelsea House Publishers, 1992.

National Institute on Drug Abuse. Marijuana: Facts Parents Need to Know. NIH Publication No. 95-4036, 1995.

National Institute on Drug Abuse. Marijuana: Facts for Teens. NIH Publication No. 95-4037, 1995.

National Institute on Drug Abuse. Marijuana: What Can Parents Do?, Videotape. NCADI Stock No. VHS82, 1995, cost $12.50.

National Institute on Drug Abuse. Preventing Drug Use Among Children and Adolescents: A Research-Based Guide. NIH Publication No. 97-5212, March 1997.

Substance Abuse and Mental Health Services Administration, Office of Applied Sciences. Preliminary Results From the 1996 National Household Survey on Drug Abuse. DHHS No. (SMA) 97-3149. Rockville, MD: SAMHSA, July 1997.

Substance Abuse and Mental Health Services Administration, Office of Applied Sciences. National Household Survey on Drug Abuse Main Findings 1996. DHHS No. (SMA) 98-3200. Rockville, MD:SAMHSA, April 1998.

U.S. Department of Education. Growing Up Drug Free: A Parent's Guide to Prevention, Washington, D.C.: NCADI Publication No. PHD533, 1993. (Note: This item is out of stock but can be viewed on the NCADI Web site at http://www.health.org.)

University of Michigan. News and Information Services. Drug use among American teens shows signs of leveling after a long rise. December 18, 1997.

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Dipartimento Politiche Antidroga
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- Alcohol and drug terms - WHO
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