NIDA for Teens: The Science Behind Drug Abuse
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  • Marijuana

    Marijuana Leaf

    Question 1

    Tetrahydrocannabinol is:

    No. Despite its technical sounding name, this chemical has no ties to the gasoline we use in cars. Try again!

    Yes! Tetrahydrocannabinol, or THC for short, is the main psychoactive ingredient in marijuana.

    No. Although it can act at the same receptors as the brain's neurotransmitter anadamide, tetrahydrocannabinl itself is not a neurotransmitter.

    No. Don't confuse this chemical with the dinosaur Tyrannosaurus Rex.

    Question 2

    The hippocampus is:

    Yes! The hippocampus is one of the places in the brain that helps us remember important things such as the information we need to pass an upcoming biology quiz. Because the hippocampus has lots of receptors for tetrahydrocannibinol, the active ingredient in marijuana, marijuana is able to act in the hippocampus to reduce memory.

    No. Though it might sound like a cool hangout place for hippos, remember the hippocampus is one of our brain areas that actually help us to remember.

    No. There are many brain areas that have a role in hearing, some of which are affected by marijuana, but the hippocampus is not one of them.

    No. The liver plays an important role in the breakdown of all drugs that enter the body, but it does not have a hippocampus.

    Question 3

    A person who has smoked marijuana may have difficulty keeping his or her balance because of marijuana’s effect on what brain area?

    No. But through its actions in the cerebral cortex, marijuana can change a user's sense of smell, vision, hearing, taste, and touch.

    No. But marijuana does act in the limbic system to produce feelings of euphoria.

    No. But users of marijuana may have trouble remembering things because of marijuana's effects on the hippocampus.

    Yes! The cerebellum is one of the most important brain areas for balance and coordination. It also contains lots of receptors for tetrahydrocannabinol, the active ingredient in marijuana, which is why someone who uses marijuana may have difficulty keeping his or her balance.

    Question 4

    A student who smokes marijuana may do poorly on a test given the next day because of marijuana’s effect on what brain area?

    No. But marijuana does act in the limbic system to produce feelings of euphoria.

    Yes! The hippocampus is an important brain area for processing memory. Users of marijuana have trouble remembering things because of marijuana's effects on the hippocampus.

    No. But users of marijuana may have problems with balance and coordination because of marijuana's effects in the cerebellum.

    No. But through it's actions in the cerebral cortex, marijuana can change a user's sense of smell, vision, hearing, taste, and touch.

  • What Is Marijuana?

     A hand holding a Marijuana leaf Marijuana is a mixture of the dried and shredded leaves, stems, seeds, and flowers of the cannabis sativa plant. The mixture can be green, brown, or gray.

    A bunch of leaves seem harmless, right? But think again. Marijuana has a chemical in it called delta-9-tetrahydrocannabinol, better known as THC. A lot of other chemicals are found in marijuana, too—about 400 of them, many of which could affect your health. But THC is the main psychoactive (i.e., mind altering) ingredient. In fact, marijuana’s strength or potency is related to the amount of THC it contains. The THC content of marijuana has been increasing since the 1970s. Estimates from confiscated marijuana indicated that it contains almost 10 percent THC, on average.

  • What Are the Common Street Names for Marijuana?

    There are many slang terms for marijuana that vary from city to city and from neighborhood to neighborhood. Some common names are: “pot,” “grass,” “herb,” “weed,” “Mary Jane,” “reefer,” “skunk,” “boom,” “gangster,” “kif,” “chronic,” and “ganja.”

  • How Is Marijuana Used?

    Marijuana is used in many ways. The most common method is smoking loose marijuana rolled into a cigarette called a “joint” or “nail.” Sometimes marijuana is smoked through a water pipe called a “bong.” Others smoke “blunts”—cigars hollowed out and filled with the drug. And some users brew it as tea or mix it with food.

  • How Many Teens Abuse Marijuana?

    Some people mistakenly believe that “everybody’s doing it” and use that as an excuse to start using marijuana themselves. Well, they need to check the facts, because that's just not true. According to NIDA's 2012 Monitoring the Future study, about 6.5% of 8th graders, 17.0% of 10th graders, and 22.9% of 12th graders had used marijuana in the month before the survey. In fact, marijuana use declined from the late 1990s through about 2007. Unfortunately, this trend appears to be reversing. Since 2007, annual, monthly, and daily marijuana use increased among 10th and 12th graders while daily use increased among 8th graders. In 2012, 6.5% of 12th graders reported using marijuana daily, compared to 5.1% in 2007.

  • What Are the Short-Term Effects of Marijuana Use?

    For some people, smoking marijuana makes them feel good. Within minutes of inhaling, a user begins to feel “high,” or filled with pleasant sensations. THC triggers brain cells to release the chemical dopamine. Dopamine creates good feelings—for a short time. But that’s just one effect…

    Imagine this: You're in a ball game, playing out in left field. An easy fly ball comes your way, and you're psyched. When that ball lands in your glove your team will win, and you'll be a hero. But, you're a little off. The ball grazes your glove and hits the dirt. So much for your dreams of glory.

    Such loss of coordination can be caused by smoking marijuana. And that's just one of its many negative effects. Marijuana affects memory, judgment, and perception. Under the influence of marijuana, you could fail to remember things you just learned, watch your grade point average drop, or crash a car.

    Also, since marijuana can affect judgment and decision making, using it can cause you to do things you might not do when you are thinking straight—such as engaging in risky sexual behavior, which can result in exposure to sexually transmitted diseases, like HIV, the virus that causes AIDS, or getting in a car with someone who’s been drinking or is high on marijuana.

    It’s also difficult to know how marijuana will affect a specific person at any given time, because its effects vary based on individual factors: a person’s genetics, whether they’ve used marijuana or any other drugs before, and how much marijuana is taken. Effects can also be unpredictable when marijuana is used in combination with other drugs.

    THC Affects Brain Functioning

    THC is up to no good in the brain. THC finds brain cells, or neurons, with specific kinds of receptors called cannabinoid receptors and binds to them.

    Certain parts of the brain have high concentrations of cannabinoid receptors. These areas are the hippocampus, the cerebellum, the basal ganglia, and the cerebral cortex. The functions that these brain areas control are the ones most affected by marijuana.

    For example, THC interferes with learning and memory—that is because the hippocampus—a part of the brain with a funny name and a big job—plays a critical role in certain types of learning. Disrupting its normal functioning can lead to problems studying, learning new things, and recalling recent events. The difficulty can be a lot more serious than forgetting if you took out the trash this morning, which happens to everyone once in a while. A recent study followed people from age 13 to 38 and found that those who used marijuana a lot in their teens and continued into adulthood had a significant drop in IQ, even if they quit.

    Smoking Marijuana Can Make Driving Dangerous

    The cerebellum is the section of our brain that controls balance and coordination. When THC affects the cerebellum’s function, it makes scoring a goal in soccer or hitting a home run pretty tough. THC also affects the basal ganglia, another part of the brain that’s involved in movement control.

    These THC effects can cause disaster on the road. Research shows that drivers on marijuana have slower reaction times, impaired judgment, and problems responding to signals and sounds. A recent analysis of data from several studies found that marijuana use more than doubles a driver’s risk of being in an accident. In fact, studies conducted in a number of localities have found that approximately 4 to 14 percent of drivers who sustained injury or death in traffic accidents tested positive for THC.

    Marijuana Use Increases Heart Rate

    Within a few minutes after inhaling marijuana smoke, an individual's heart begins beating more rapidly, the bronchial passages relax and become enlarged, and blood vessels in the eyes expand, making the eyes look red. The heart rate, normally 70 to 80 beats per minute, may increase by 20 to 50 beats per minute or, in some cases, even double. This effect can be greater if other drugs are taken with marijuana.

  • What Are the Long-Term Health Effects of Marijuana Use?

    The Brain

    When people smoke marijuana for years, they can suffer some pretty negative consequences. For example, because marijuana affects brain function, your ability to do complex tasks could be compromised, as well as your pursuit of academic, athletic, or other life goals that require you to be 100-percent focused and alert. In fact, people who use marijuana over the long term report less life satisfaction, poorer education, and job achievement, and more interpersonal problems compared to people who do not use marijuana.

    Marijuana also may affect your mental health. Studies show that early marijuana use may increase your risk of developing psychosis if you have a genetic vulnerability to the disease. Psychosis is a severe mental disorder in which there is a loss of contact with reality, including false ideas about what is happening (delusions) and seeing or hearing things that aren’t there (hallucinations). Marijuana also has been associated with depression and anxiety, but more research is necessary to confirm and better understand that relationship.

    Addiction

    Many people don’t think of marijuana as addictive—they are wrong. About 9 percent of people who use marijuana become dependent on it. The number increases to about one in six among those who start using it at a young age, and to 25 to 50 percent among daily users. Marijuana increases dopamine, which creates the good feelings or “high” associated with its use. A user may feel the urge to smoke marijuana again, and again, and again to re-create that experience. Repeated use could lead to addiction—a disease where people continue to do something, even when they are aware of the severe negative consequences at the personal, social, academic, and professional levels.

    People who use marijuana may also experience a withdrawal syndrome when they stop using the drug. It is similar to what happens to tobacco smokers when they quit—people report being irritable, having sleep problems, and weight loss—effects which can last for several days to a few weeks after drug use is stopped. Relapse is common during this period, as users also crave the drug to relieve these symptoms.

    Lungs and Airways

    People who abuse marijuana are at risk of injuring their lungs through exposure to respiratory irritants found in marijuana smoke. The smoke from marijuana contains some of the same chemicals found in tobacco smoke; plus, marijuana users tend to inhale more deeply and hold their breath longer, so more smoke enters the lungs. Not surprisingly, people who smoke marijuana have some of the same breathing problems as those who smoke tobacco—they are more susceptible to chest colds, coughs, and bronchitis than people who do not smoke.  

  • Does Marijuana Use Lead to the Use of Other Drugs?

    While most people who smoke marijuana do not go on to use other drugs, long-term studies of high school students show that few young people use other illegal drugs without first trying marijuana. For example, the risk of using cocaine is much greater for those who have tried marijuana than for those who have never tried it. Using marijuana puts children and teens in contact with people who use and sell other drugs. So, a person who uses marijuana is more likely to be exposed to and urged to try other drugs. The effects of marijuana on the brain of adolescents—still a work in progress—may also affect their likelihood of using other drugs as they get older. Animal studies suggest this to be true, but it is not yet demonstrated in people.

  • What About Medical Marijuana?

    Under U.S. law since 1970, marijuana has been a Schedule I controlled substance. This means that the drug has no approved medical use. Twenty states and the District of Columbia have legalized marijuana for medical use even though it hasn’t been approved by the Food and Drug Administration (FDA) to be a medicine. There are a few reasons why it hasn’t been approved. There haven’t been enough studies to show that its benefits outweigh its harms—that is, that it doesn’t cause more problems than it treats. Also, because it is a plant, there is no way to know how much or exactly what chemicals a person is getting each time they use it (unlike with a pill or shot).

    That said, there are medications containing synthetic (man-made)THC, the main active ingredient in marijuana, that are used to treat nausea in cancer patients undergoing chemotherapy, and to stimulate appetite in patients with wasting syndrome—severe, involuntary weight loss—due to AIDS.

    Since the discovery of the cannabinoid system—receptors in the body that bind THC, and chemicals that act as these receptors—scientists are actively looking for ways to use this system for medical purposes. Several promising compounds are being tested for the treatment of obesity, pain, and other disorders. However, it is unlikely that smoked marijuana will be developed as a medication because of its negative health effects.

  • What if a Person Wants To Quit Using Marijuana?

    Researchers are testing different ways to help people who use marijuana abstain from drug use. Currently, no medications exist for treating marijuana addiction. Treatment programs focus on behavioral therapies. A number of programs are designed specifically to help teenagers who abuse marijuana.

    When someone has a drug problem, it's not always easy to know what to do. If someone you know is using marijuana, encourage him or her to talk to a parent, school guidance counselor, or other trusted adult. There are also anonymous resources, such as the National Suicide Prevention Lifeline (1-800-273-TALK) and the Treatment Referral Helpline (1-800-662-HELP).

    The National Suicide Prevention Lifeline (1-800-273-TALK) is a crisis hotline that can help with a lot of issues, not just suicide. For example, anyone who feels sad, hopeless, or suicidal; family and friends who are concerned about a loved one; or anyone interested in mental health treatment referrals can call this Lifeline. Callers are connected with a professional nearby who will talk with them about what they’re feeling or concerns for other family and friends.

    In addition, the Treatment Referral Helpline (1-800-662-HELP)—offered by the Substance Abuse and Mental Health Services Administration—refers callers to treatment facilities, support groups, and other local organizations that can provide help for their specific need. You can also locate treatment centers in your state by going to www.samhsa.gov/treatment.