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). Cannabis is a term that refers to marijuana and other drugs made from the same plant. Strong forms of cannabis include sinsemilla (sin-seh-me-yah), hashish ("hash" for short), and hash oil. There are many different slang terms for marijuana and, as with other drugs, they change quickly and vary from region to region. But no matter its form or label, all cannabis preparations are mind-altering (psychoactive) because they all contain THC (delta-9-tetrahydrocannabinol). They also contain more than 400 other chemicals.
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 or a water pipe, sometimes referred to as a 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, creating what is known as a blunt. Marijuana cigarettes or blunts sometimes are dipped in PCP or mixed with other substances, including crack cocaine.
Q. How many people use marijuana?
A. Before the 1960s, many Americans had never heard of marijuana, but today it is the most often used illegal drug in the United States. According to a 2009 national survey, more than 104 million Americans over the age of 12 had tried marijuana at least once, and almost 17 million had used the drug in the month before the survey.
Researchers have found that the use of marijuana and other drugs usually peaks in the late teens and early twenties, and then declines in later years. Therefore, marijuana use among young people remains a natural concern for parents and the focus of continuing research, particularly regarding its impact on brain development, which continues into a person's early twenties.
NIDA's annual Monitoring the Future Survey reports that among students from 8th, 10th, and 12th grades, most measures of marijuana use have decreased over the past decade; however, this decline has stalled in recent years as attitudes have softened about marijuana's risks. In 2009, 11.8 percent of 8th-graders reported marijuana use in the past year, and 6.5 percent were current (past-month) users. Among 10th-graders, 26.7 percent had used marijuana in the past year, and 15.9 percent were current users. Rates of use among 12th-graders were higher still: 32.8 percent had used marijuana during the year prior to the survey, and 20.6 percent (or about 1 in 5) were current users.
Q. How does marijuana work?
A. When marijuana is smoked, its effects are felt almost immediately. This is because THC (marijuana's psychoactive ingredient) rapidly reaches every organ in the body, including the brain. The effects of smoked marijuana can last from 1 to 3 hours. If consumed in foods, the effects come on slower and may not last as long.
Marijuana works through THC attaching to specific sites on nerve cells in the brain and in other parts of the body. These sites are called cannabinoid receptors (CBRs) since they were discovered by scientists trying to understand how marijuana, or cannabis, exerts its effects. THC is chemically similar to a class of chemicals that our body produces naturally, called endocannabinoids, and marijuana disrupts the normal function of this system. CBRs are found in brain areas that influence pleasure, memory, thinking, concentration, movement, coordination, appetite, pain, and sensory and time perception. Because of this system's wide-ranging influence over many critical functions, it is not surprising that marijuana can have multiple effects—not just on the brain, but on a user's general health as well. Some of these effects are related to acute intoxication while others may accumulate over time to cause more persistent problems, including addiction.
Q. What are marijuana's short-term effects?
A. The following are some effects that marijuana use can produce:
- Euphoria (high). THC activates the reward system in the same way that nearly all drugs of abuse do: by stimulating brain cells to release the chemical dopamine.
- Memory impairment. THC alters how information is processed in the hippocampus, a brain area responsible for memory formation, causing problems with short-term memory as well as difficulty with complex tasks requiring sustained attention/concentration. Prolonged use could therefore affect learning skills and academic achievement.
- Increased appetite ("munchies").
- Increased heart rate.
- Dilation (expansion) of the blood vessels in the eyes, making them look red or bloodshot.
- Adverse mental reactions in some. These include anxiety, fear, distrust, or panic, particularly in those who are new to the drug or who are taking it in a strange setting; and acute psychosis, which includes hallucinations, delusions, paranoia, and loss of the sense of personal identity.
Q. What determines how marijuana affects an individual? How important is marijuana potency?
A. Like any other drug, marijuana's effects on an individual depend on a number of factors, including the person's previous experience with the drug (or other drugs), biology (e.g., genes), gender, how the drug is taken (smoked versus orally), and the drug's potency. Potency—determined by the amount of THC contained in the marijuana—has received much attention lately because it has been increasing steadily. In 2009, THC concentrations in marijuana averaged close to 10 percent, compared to around 4 percent in the 1980s. This is based on analyses of marijuana samples confiscated by law enforcement agencies. So what does this actually mean? For a new user, it may mean exposure to higher concentrations of THC, with a greater chance of an adverse or unpredictable reaction. In fact, increases in potency may account for the rise in emergency department visits involving marijuana use. For experienced users, it may mean a greater risk for addiction if they are exposing themselves to high doses on a regular basis. However, the full range of consequences associated with marijuana's higher potency is not well understood, nor is it known whether marijuana users adjust for the increase in potency by using less.
Q. Does using marijuana lead to other drug use?
A. Long-term studies of high school students' patterns of drug use show that most young people who use other drugs have tried marijuana, alcohol, or tobacco first. That said, many young people who use marijuana do not go on to use other drugs. It is clear that more research is needed to determine who is at greatest risk. For example, the risk of young people using cocaine is much greater for those who have tried marijuana than for those who have not (though teen cocaine use is low overall). We also know from animal studies that when rats are exposed to cannabinoids their brain reward system becomes less sensitive, or responsive, to that drug, which means that they would need more of the drug to achieve the same effect. An important aspect of this effect is a phenomenon called cross-tolerance (the ability of one drug to reduce responsiveness to a different drug). This was only seen if the rats that were givencannabinoids were young (e.g., adolescent) at the time of exposure. Prompted by the results of this animal study, researchers are now examining the possibility that early exposure to marijuana (e.g., in adolescence) may induce changes in the brain that make a person more vulnerable to subsequent marijuana addiction or to the risk of becoming addicted to other drugs, such as alcohol, opioids, or cocaine. It is important to point out, however, that research has not fully explained any of these effects, which are complex and likely to involve a combination of biological, social, and psychological factors.
Q. Does smoking marijuana cause lung cancer?
A. We do not know yet. Studies have not found an increased risk of lung cancer in marijuana smokers, as compared with nonsmokers. However, marijuana smoke does irritate the lungs and increases the likelihood of other respiratory problems through exposure to carcinogens and other toxins. Repeated exposure to marijuana smoke can lead to daily cough and excess phlegm production, more frequent acute chest illnesses, and a greater risk of lung infections. Marijuana also affects the immune system, although the implications for cancer are unclear. Moreover, many people who smoke marijuana also smoke cigarettes, which do cause cancer, and quitting tobacco can be harder if the person uses marijuana as well.
Q. Since marijuana is addictive, does it produce withdrawal symptoms when someone quits using it?
A. For many years, this was a subject of debate; but researchers have clearly characterized a set of symptoms that many long-term users experience when they stop using the drug. The symptoms are similar in type and severity to those of nicotine withdrawal— irritability, sleeping difficulties, anxiety, and craving—which often prompt relapse. Withdrawal symptoms peak a few days after use has stopped and dissipate within about 2 weeks. And while these symptoms do not pose an immediate threat to the health of the user, they can make it hard for someone to remain abstinent.
Q. Are there treatments for people addicted to marijuana?
A. Currently, no FDA-approved medications exist for treating marijuana addiction, although promising research is under way to find medications for treating withdrawal symptoms and alleviating craving and other subjective effects of marijuana. Behavioral therapies are available and are similar to those used for treating other substance addiction. These include motivational enhancement to engage people in treatment; cognitive behavioral therapies to teach patients strategies for avoiding drug use and its triggers and for effectively managing stress; and motivational incentives, which provide vouchers or small cash rewards for sustained drug abstinence. Unfortunately, treatment success rates are rather modest, indicating that marijuana addiction, like other addictions, may need a chronic care approach that varies treatment intensity in line with the person's changing needs over time.
Q. What are other risks related to marijuana that my child should be aware of?
A. Here are a few that you or your child may not have thought about:
- As with most drugs, marijuana use compromises judgment, which can mean a greater likelihood of engaging in risky behaviors and experiencing their negative consequences (e.g., acquiring a sexually transmitted disease, driving while intoxicated, or riding with someone else who is intoxicated and getting into a car crash).
In addition to psychosis, chronic marijuana use has been associated with an array of psychological effects, including depression, anxiety, suicidal thoughts, and personality disturbances. One of the most frequently cited is an "amotivational syndrome," which describes a diminished or lost drive to engage in formerly rewarding activities.
Whether this disorder occurs unto itself or is a subtype of depression associated with marijuana use remains controversial, as does the causal influence of marijuana. However, because of the endocannabinoid system's role in regulating mood, these associations seem plausible. More research is needed to confirm and better understand these linkages.
Q. How can I tell if my child has been using marijuana?
A. Parents should be aware of changes in their child's behavior, such as carelessness with grooming, mood changes, and deteriorating relationships with family members and friends. In addition, changes in academic performance, increased absenteeism or truancy, lost interest in sports or other favorite activities, and changes in eating or sleeping habits could all be related to drug use—or may indicate other problems. See textbox for a more detailed list of warning signs.
If someone is high on marijuana, he or she might:
- seem dizzy or uncoordinated;
- seem silly and giggly for no reason;
- have very red, bloodshot eyes;
- have a hard time remembering things that just happened;
- be in possession of drugs and drug paraphernalia, including pipes and rolling papers;
- have an odor on clothes and in the bedroom;
- use incense and other deodorizers;
- use eye drops;
- wear clothing or jewelry or have posters that promote drug use; or
- have unexplained use of money.
As a result of scientific research, we know that addiction is a disease that affects both brain and behavior.