Marijuana is the dried leaves and flowers of Cannabis Sativa. Delta-9-tetrahydrocannabinol (THC) is the main active ingredient in marijuana that causes people who use it to experience a calm euphoria. Marijuana changes brain messages that affect sensory perception and coordination. This can cause users to see, hear, and feel stimuli differently and to exhibit slower reflexes.
- Associated Drug of Abuse:
- September 08, 2014
This is the first post of a 3-part series on the science of medical marijuana. Check out Part 2: Making Medicine From Marijuana, and Part 3: Medicines or Poisons?—Why Cannabinoids Can Both Help and Hurt You.
Before modern medical science, most medicines were raw herbs or herbal concoctions of one sort or another. They sometimes helped patients, but those benefits weren’t very powerful by today’s standards, and they often had a lot of unpredictable or even dangerous side effects. That’s because all plants contain hundreds or thousands of different chemicals. If you eat or smoke the leaves of any plant, you are putting all those chemicals in your body, and the results can be unpredictable.
Marijuana is no different.
Still, there is growing public support for “medical marijuana,” based on anecdotal evidence (that is, from individual people’s personal experience) that the drug might be useful in treating various diseases, including PTSD (post-traumatic stress disorder), pain, and epilepsy.
Voters in 23 states have now passed laws allowing marijuana to be dispensed to patients, as long as they receive permission from a doctor.
Why Doesn’t the Food and Drug Administration (FDA) Approve “Medical Marijuana”?
Turns out, there’s very little scientific evidence that smoking or eating marijuana is effective and safe for treating any medical issues. Scientific evidence would have to come from carefully controlled research studies.
Since there’s no science to back it up, the FDA has not approved smoked or vaporized marijuana for the treatment of any medical condition.
The FDA only approves medicines when large studies examining lots of patients (called clinical trials) show that the medicines work safely. Without these studies, the FDA can’t promise people that the medications will help them and not harm them.
So why haven’t there been clinical trials on marijuana?
Because marijuana is a raw herb. There are over 500 different chemicals in marijuana, in combinations that vary widely between different strains and even from plant to plant. This causes serious problems trying to use the whole marijuana leaf, or crude extracts like hash oil, as medicine:
- It’s hard to deliver precise, accurate doses of the right chemicals;
- It can harm the lungs if users smoke it; and
- It causes additional effects—like the “high”—that may interfere with the quality of life of patients taking the drug for serious medical conditions.
Plus, when used by teens or children, it could even harm their brains as they develop.
Today, there are almost no approved medicines that are whole herbs. Although it’s not impossible, it would be very unusual if marijuana became an exception.
So how can we discover and use marijuana’s medical benefits without the harms?
Stay tuned for Part 2, to learn how scientists are busy trying to create actual medicines from the chemical ingredients in marijuana.
- December 01, 2014Studies show that marijuana interferes with attention, motivation, memory, and learning. Students who use marijuana regularly tend to get lower grades and are more likely to drop out of high school than those who don’t use. Those who use it regularly may be functioning at a reduced intellectual level most or all of the time.Check out NIDA's new infographic that explains what that means in the classroom, and how that can affect your life.[Click here to view larger version of this infographic or the text-only version]
Mechanism of Action
THC, the main active ingredient in marijuana, binds to and activates specific receptors, known as cannabinoid receptors. There are many of these receptors in parts of the brain that control memory, thought, concentration, time and depth perception, and coordinated movement. By activating these receptors, THC interferes with their normal functioning.
The cerebellum is a part of the brain involved in balance, posture, and coordination of movement. The cerebellum coordinates the muscle actions ordered by the motor cortex. Nerve impulses alert the cerebellum that the motor cortex has directed a part of the body to perform a certain act. Almost instantly, impulses from that part of the body inform the cerebellum as to how the action is being carried out. The cerebellum compares the actual movement with the intended movement and then signals the motor cortex to make any necessary corrections. In this way, the cerebellum ensures that the body moves smoothly and efficiently.
The hippocampus is involved with memory formation. Studies suggest that marijuana affects memory by decreasing the activity of neurons in this area. Because the hippocampus is involved in new memory formation, someone under the influence of marijuana will have impaired short-term memory, and new learning may be compromised. However, most studies in humans suggest that if a person stops using marijuana, their memory abilities can recover.
Marijuana also affects brain areas responsible for sensory perception (for example, touch, sight, hearing, taste, and smell) in the cerebral cortex. Most sensory information that comes from the body is routed through the thalamus, and then on to appropriate areas of the cerebral cortex. For example, the somatosensory cortex receives messages interpreted as body sensations, such as touch. The somatosensory cortex lies in the parietal lobe of each hemisphere. The somatosensory cortex is organized in such a way that the entire body is represented, so that it can receive and accurately interpret impulses from a specific body part. Other specialized areas of the cerebral cortex receive the sensory impulses related to seeing, hearing, taste, and smell. Impulses from the eyes travel along the optic nerve and then are relayed via the thalamus to the visual cortex in the occipital lobes. Portions of the temporal lobes receive auditory messages from the ears. The area for taste lies buried in the lateral fissure, which separates the frontal and temporal lobes. The center for smell is on the underside of the frontal lobes-smell is the only sense that is not relayed through the thalamus. Olfactory nerves carrying this information go through the olfactory bulb and directly to the cortex. Marijuana activates cannabinoid receptors in these various cortical areas, leading to altered sensory perception that users experience under the influence.
In the late 1980’s, it was discovered that THC acted at specific receptors in the brain, which became known as cannabinoid receptors. It was then hypothesized that, because these receptors exist, there must also be a substance naturally produced in the brain that acts on them. In 1992, scientists discovered a substance that activates the THC receptors and has many of the same physiological effects as THC. The scientists named the substance anandamide, from a Sanskrit word meaning “bliss.” The discovery of anandamide opened whole new avenues of research, which led to the discovery of additional cannabinoid molecules and receptors. One of these, 2-arachidonoglycerol, is similar to anandamide, and helps control pain. Scientists continue to study the functions of anandamide and 2-arachidonoglycerol in the brain, with the hope of understanding not just how marijuana exerts its actions and why it is abused, but also how the cannabinoid system contributes to brain function under normal (non-drug) conditions.
Marijuana’s potential medicinal effects have long been hypothesized. Indeed, oral forms of THC (e.g., marinol) are already currently available to treat nausea associated with chemotherapy and to stimulate appetite in AIDS wasting syndrome. The discovery of the brain's own THC-like substances, and their unique mode of action, should help uncover the mechanisms underlying the therapeutic potential of cannabinoids, which could then lead to the development of more effective and safer treatments for a variety of conditions, including addiction, pain, obesity, multiple sclerosis, etc.
The following activities will help explain to students how these substances change the brain and the body.
"Spice" refers to a wide variety of herbal mixtures that produce experiences similar to marijuana (cannabis) and that are marketed as "safe," legal alternatives to that drug. Sold under many names, including K2, fake weed, Yucatan Fire, Skunk, Moon Rocks, and others — and labeled "not for human consumption" — these products contain dried, shredded plant material and chemical additives that are responsible for their psychoactive (mind-altering) effects.
Labels on Spice products often claim that they contain "natural" psycho-active material taken from a variety of plants. Spice products do contain dried plant material, but chemical analyses show that their active ingredients are synthetic (or designer) cannabinoid compounds.
For several years, Spice mixtures have been easy to purchase in head shops and gas stations and via the Internet. Because the chemicals used in Spice have a high potential for abuse and no medical benefit, the Drug Enforcement Administration (DEA) has designated the five active chemicals most frequently found in Spice as Schedule I controlled substances, making it illegal to sell, buy, or possess them. Manufacturers of Spice products attempt to evade these legal restrictions by substituting different chemicals in their mixtures, while the DEA continues to monitor the situation and evaluate the need for updating the list of banned cannabinoids.
Spice products are popular among young people; of the illicit drugs most used by high-school seniors, they are second only to marijuana. (They are more popular among boys than girls — in 2012, nearly twice as many male 12th graders reported past-year use of synthetic marijuana as females in the same age group.) Easy access and the misperception that Spice products are “natural” and therefore harmless have likely contributed to their popularity. Another selling point is that the chemicals used in Spice are not easily detected in standard drug tests.
How Is Spice Abused?
Some Spice products are sold as “incense,” but they more closely resemble potpourri. Like marijuana, Spice is abused mainly by smoking. Sometimes Spice is mixed with marijuana or is prepared as an herbal infusion for drinking.
K2, a popular brand of “Spice” mixture. Image courtesy of Coolidge Youth Coalition
How Does Spice Affect the Brain?
Spice users report experiences similar to those produced by marijuana—elevated mood, relaxation, and altered perception—and in some cases the effects are even stronger than those of marijuana. Some users report psychotic effects like extreme anxiety, paranoia, and hallucinations.
So far, there have been no scientific studies of Spice’s effects on the human brain, but we do know that the cannabinoid compounds found in Spice products act on the same cell receptors as THC, the primary psychoactive component of marijuana. Some of the compounds found in Spice, however, bind more strongly to those receptors, which could lead to a much more powerful and unpredictable effect. Because the chemical composition of many products sold as Spice is unknown, it is likely that some varieties also contain substances that could cause dramatically different effects than the user might expect.
What Are the Other Health Effects of Spice?
Spice abusers who have been taken to Poison Control Centers report symptoms that include rapid heart rate, vomiting, agitation, confusion, and hallucinations. Spice can also raise blood pressure and cause reduced blood supply to the heart (myocardial ischemia), and in a few cases it has been associated with heart attacks. Regular users may experience withdrawal and addiction symptoms.
We still do not know all the ways Spice may affect human health or how toxic it may be, but one public health concern is that there may be harmful heavy metal residues in Spice mixtures. Without further analyses, it is difficult to determine whether this concern is justified.
For more information on Spice, seePublication from NIDA:Yes
- September 15, 2014
This is the second post of a 3-part series on the science of medical marijuana. Check out Part 1: What’s Wrong With “Medical Marijuana”? and Part 3: Medicines or Poisons?—Why Cannabinoids Can Both Help and Hurt You.
What people usually mean by “medical marijuana” is use of an unprocessed (raw) plant to treat illness—or herbal medicine, in other words. Unprocessed means the leaves, stems, or seeds are just taken off the plant and used.
Before the 20th century, that’s mostly what medicine was.
But science has made a lot of progress in the last several decades, and generally it hasn’t looked back. It’s because we now have ways of picking out the specific chemicals that are useful from plants and putting just those parts in a pill, without all the unwanted chemicals that might cause side effects or even be toxic.
This is what a lot of scientists are busy doing right now with marijuana—trying to figure out which chemicals in the plant really are useful in treating health problems and then finding ways to deliver them safely and effectively to patients to treat their conditions.
Turning Marijuana into Medicine
At the last count, scientists have found over 500 separate chemicals in the marijuana plant. The main chemical that gives users the “high” is tetrahydrocannabinol, or THC, but there are over 100 other chemicals in marijuana that have a similar molecular structure to THC. This family of chemical compounds is called cannabinoids.
So far, there are two FDA-approved medications containing THC for treating nausea and appetite problems caused by cancer chemotherapy and AIDS. Other drugs with THC in them have been approved already in other countries for treating symptoms of multiple sclerosis (MS) and are now being carefully tested before being approved in the United States.
Another marijuana chemical is cannabidiol, or CBD. News reports have highlighted some families who are living in states where medical marijuana is legal so their children with bad forms of epilepsy can get special high-CBD marijuana extracts to help control seizures.
These extracts probably still contain other, possibly harmful ingredients. But a medicine only containing CBD is now being tested in the United States. If the science finds that CBD really is a good treatment for seizures, eventually patients may be able to take that or another safe, CBD-based medication. This could help people get the safe treatment they need.
Cannabinoids and Other Diseases
Lots of different cannabinoid chemicals are being studied to see whether they have beneficial effects on conditions ranging from addictions and other mental health problems to pain and other serious conditions. Most are still a long way from being studied in humans and going on to become medications.
In Part 3, we’ll look at why chemicals in the marijuana plant could be so helpful even though they may also be harmful. It turns out, marijuana’s not unique in being two-faced!
- February 02, 2015
Last week, the American Academy of Pediatrics (AAP), an organization that represents doctors who specialize in treating children and adolescents, published a statement opposing most uses of medical marijuana and the legalization of marijuana, because of the possible ways the drug can harm young people.
You’re aware that there’s been a lot of talk about whether the government should relax its marijuana laws, or even make it legal. There are lots of strong opinions for and against. So far, voters in four states and the District of Columbia have voted to legalize adult recreational use of marijuana.
Nearly half of the states have also passed laws allowing medical use of marijuana, even though so far there’s very little science supporting it. The Food and Drug Administration (FDA), which puts its stamp of approval on medicines, has never approved it.
Doctors who treat young people are worried about the long-term dangers of exposure to marijuana when the brain is still growing—usually until you’re in your early 20s. Studies show that young people are especially vulnerable to becoming addicted to drugs, including marijuana. And heavy use of marijuana in the teen years can lead to loss of intelligence—which can have a horrible domino effect in a person’s life—worse grades, worse jobs, worse relationships, and so on.…
The AAP also recommended that, in places where marijuana has already been legalized, authorities take steps to keep it out of the hands of young people and to place limits on advertising that might make it seem appealing to kids.
Although the AAP is opposed to most medical marijuana—and especially against using marijuana to treat children and teens—it does support loosening the legal restrictions (“scheduling”) on marijuana that sometimes make it hard for researchers to study the possible health benefits of the plant and the cannabinoid chemicals it contains. More research could lead to FDA-approved drugs that use these potentially healing chemicals, but do not require smoking the plant, which can affect your lung health.
Tell us what you think: Are these doctors right? Do you think more kids would use marijuana if it was made legal? Do you think most teens realize their brain is still growing and could be affected by marijuana use?Tags:Medical Marijuana
The student will understand the effects of marijuana on the brain structures that control the five senses, emotions, memory, and judgment.
The student will use knowledge of brain-behavior relationships to determine the possible effects of marijuana on the ability to perform certain tasks and occupations.
Review the way marijuana use affects brain regions and structures that control the five senses, heart rate, emotions, memory, and judgment. Students will then randomly select (for example, draw from a hat) an occupation and be asked to act out, in front of the class, how marijuana use might specifically affect the performance of a person in that occupation. (Examples: airline pilot, professional basketball player, doctor, defense attorney, truck driver, construction worker, server in a restaurant, politician.) Students will identify the brain regions and structures affected by marijuana use, and describe the link between these structures and behavior.
All materials appearing in the Research Reports series are in the public domain and may be reproduced without permission from NIDA. Citation of the source is appreciated.Publication from NIDA:Yes
- September 22, 2014
People who write about the health benefits of marijuana sometimes think it’s ironic that a plant containing compounds that could treat disease (like THC or CBD) is banned by the government for being unsafe. But in fact many effective, FDA-approved medicines are closely related to illegal, harmful drugs and are sometimes even made from the same sources.
That’s because there’s a fine (and sometimes fuzzy) line between chemicals that are good for you and those that can hurt or even kill you. In fact, the Greek word pharmakon, where we get pharmacy, originally meant both “medicine” and “poison.”
Speaking the Body’s Language
The opium poppy is a great example. It’s the source of a drug called morphine, part of a class of drugs called opioids. Morphine is used to make heroin—a very addictive and sometimes deadly drug. But it is also modified and used to make many effective, relatively safe pain relievers prescribed widely by doctors and dentists. In fact, these opioids are our most valuable drugs for pain relief.
Another example is cocaine, from the coca plant. It is part of a class of drugs called stimulants. Cocaine is an especially dangerous, addictive stimulant, but it is closely related to medications used to treat people with attention deficit hyperactivity disorder (ADHD) and other conditions. It is also used sometimes as an anesthetic.
The thing that makes a drug a drug is the ability to speak the body’s language—specifically, to interact with one of the many chemical signaling systems that cells use to talk to each other. Both heroin and cocaine are able to do that, fluently.
Same with marijuana: Its cannabinoid chemicals speak the body’s own endocannabinoid language.
Nerve cells use chemicals called neurotransmitters to send each other messages, and there are several different kinds of neurotransmitters. Similar chemicals in plants or in foods can interact with these neurotransmitter systems because their molecules are very similar to the ones produced naturally in the human body.
Morphine from the poppy plant is able to work in your nervous system because it closely resembles your body’s own natural pain-relieving opioid chemicals—the endorphins that cause a “runner’s high.” (The “endo” in endorphin or endocannabinoid means “from inside”—that is, inside your body.)
Cocaine and related stimulants work with your own neurotransmitter dopamine, which naturally keeps you focused on rewarding activities.
And the THC in marijuana interacts with the endocannabinoid signaling system used by the body’s own cannabinoid chemicals—such as anandamide—in brain circuits that control a wide range of things including pleasure, memory, thinking, concentration, movement, coordination, and even how you perceive time. That’s why THC is able to interfere with these abilities when people smoke marijuana either to get high or to treat a medical condition.
The endocannabinoid system also is involved in things like appetite and pain, which is why THC has been made into an effective medication for helping treat nausea and loss of appetite in AIDS and cancer-chemotherapy patients. And it is why it may, in the future, be prescribed for treating pain as well.
So, there’s nothing special about marijuana: It’s one of many plants that contain substances that can be both beneficial and harmful, depending on how they are used.
- February 05, 2015
With so much hype about marijuana legalization and the “drug war,” it’s easy to think that marijuana is just a modern phenomenon (or invented by the hippies). But the cannabis (or hemp) plant has had a long—really long!—history. And while the plant, and the way it is used, has changed a lot over the centuries, it’s interesting to take the long view of marijuana and look back at its history. For this three-part series, we’ll be your tour guide of cannabis through the ages.
Starting in Asia…
The cannabis or hemp plant (which only came to be called marijuana in the 20th century) has a long history, going back several thousand years—first in Central Asia, then spreading east to China, south to India, and westward to Europe, the Middle East, and Africa.
In most ancient cultures, though, “getting high” was not the main use for the plant. Hemp fiber was valued for making clothes and other textiles, and its seeds were used for food and oil. The types of plant used for these purposes had very low amounts of THC, the chemical that causes intoxication.
The ancients did know, however, about the plant’s mind-altering properties and may have bred varieties for this purpose as well. The oldest evidence of this is the remains of burned cannabis seeds that have been found in graves of shamans—religious leaders and healers—in China and Siberia from around 500 BC.
Ancient “Medical Marijuana”
Shamans enlisted the aid of spirits to help their community and try to cure sickness. Sometimes this was done with the help of intoxicating substances, and it is likely that cannabis was used this way. It probably wasn’t “recreational” but was believed to be a serious religious and healing tool to be respected.
We now know that THC can be used medically to treat nausea—in fact, two FDA-approved drugs with THC are prescribed in pill form to people who feel sick or have no appetite as a result of chemotherapy or AIDS. The ancients seem to have used cannabis to treat similar ailments. It appears in ancient medical texts from ancient Egypt, and ancient Greek physicians described using it for stomach problems.
Cannabis as a Recreational Drug
The oldest evidence of marijuana being used recreationally comes from an ancient Greek historian named Herodotus (484–425 BC). He described how people of a Eurasian society called the Scythians inhaled the vapor of cannabis seeds and flowers thrown on heated rocks. It might have not sounded that appealing to his Greek readers, though, who much preferred to get “high” on wine, as did the Romans later.
The first drug to rival alcohol for popularity in Europe was tobacco, imported from America in the late 1500s. Coffee followed about a century later, imported from Africa. And although Europeans cultivated hemp and occasionally smoked cannabis, its popularity didn’t match that of alcohol, tobacco, and coffee.
Unlike in Europe, however, cannabis (in the concentrated form called hashish) did become widely used in the Middle East and South Asia after about 800 AD. The reason has to do with the spread of Islam. The Koran strictly forbade Muslims from drinking alcohol or partaking in other intoxicating substances, but it did not specifically mention cannabis. Cannabis is prohibited in most Islamic countries today, though, as it is throughout much of the world.
Part 2 of this series gives a brief history of cannabis in America and answers the question: Did the Founding Fathers really smoke it, as rumors have claimed?
The student will understand how marijuana interferes with information transfer and short-term memory.
Read aloud a list of 20 words to the class; then ask the students to write down as many words as they can remember. Next, have several students, stand in pairs around the room and carry on loud conversations while you read another list of 20 words to the remainder of the class. Ask students once again to write down as many of the words as they can remember. Compare the performance of the two trials. Tell the students that, like the disruptive pairs of students, marijuana interferes with normal information transfer and memory. Students will then identify the areas of the brain and structures responsible for these functions and will be reminded that marijuana alters neurotransmission in these areas. Students can also search the Internet and other sources for more research into the effects of marijuana on information transfer and memory, and then prepare a brief report summarizing their findings.
- English DrugPub ID:NIH10-4037Publication from NIDA:Yes
- October 06, 2014
Marijuana has long been seen as an “alternative” drug. It was illegal for everyone, and those who used it regularly were seen as “stoners” or “hippies” or “partiers” and were somehow different than “regular” people. There was a stereotype of people who used marijuana and most people didn’t think much about it.
And then came the rise of medical marijuana, and that began to change marijuana’s reputation. It was seen, by some, as medicine, and in some states people were able to get a prescription for it and use it to help them with specific health problems. Marijuana started to change its image. Now, along with the typical marijuana user, there were people who had medical conditions enabling them to get a prescription and use marijuana legally.
But the biggest change in marijuana’s image is what has happened in two states, Colorado and Washington, where marijuana has been made legal for adults to use, with or without a prescription. This change pushed marijuana out of the shadows and into the spotlight.
Marijuana is still not as popular as alcohol or tobacco in those states, but this new identity as a “legal drug” has come with a change in perception that marijuana is safe, and that the reasons it was illegal before no longer exist.
This really worries people who dedicate their lives to the health of the public. That’s especially true when it comes to people who care about teens, whose brains are actively developing and may really be damaged by marijuana use.
Colorado is working to counter the effects of marijuana’s image makeover by constructing human-sized rat cages to raise awareness about the effects of marijuana on young people, getting the point across that using it as a teenager is kind of like doing an experiment on your brain. Thus the campaign’s message: “Don’t be a lab rat” and questions like “Can marijuana really cause schizophrenia in teenagers? Volunteers, anyone?” The cages are displayed in places popular with kids and teens, such as a skate park and the public library.
Tell us in comments: Do you think advertising campaigns can help teens see that marijuana is still dangerous for them to use?
- February 19, 2015
Recently, the NIDA Blog Team brought the science of marijuana to life in a series of posts about the drug’s effects on your brain, perception, pets, driving, and more. Here are a few highlights!
1. Marijuana use interferes with attention, motivation, memory, and learning. When used heavily during the teen years, it can lower grades and your IQ.
2. Exposure to secondhand marijuana smoke rarely results in a contact high.
3. Serving sizes for marijuana edibles are confusing—it’s easy to eat much more than a person means to, with bad side effects.
4. Marijuana doesn’t make you more creative—it just makes you think you are.
Dude, this is my masterpiece.
5. Marijuana can make dogs ill, causing serious medical issues such as injury, dehydration, anxiety, lethargy, impaired balance, vomiting, or diarrhea. A few have even died from eating it.
6. Drugged driving is dangerous, illegal, and happening more and more. The risk of being in an accident doubles after marijuana use.
Do you know why I pulled you over?
7. Over three-quarters of the students surveyed in the Monitoring the Future study (and four-fifths of 8th graders) said they disapproved of people using marijuana regularly.
8. Spice, also known as K2, is not fake marijuana. In fact, some effects of Spice are much more intense than those of marijuana and have even been linked to deaths.
9. A small number of medications that contain THC are approved by the Food and Drug Administration. They are used for treating nausea and appetite problems caused by cancer chemotherapy and AIDS. Marijuana’s other chemical—cannabidiol or CBD—also is being studied for potential medical uses, including treatment for seizures.
10. Ancient healers used cannabis in religious ceremonies—not as a party drug.
That’s old school.
The student will learn more about the important role of the cerebellum.
Explain that the cerebellum is involved in balance, coordination, and a variety of other regulatory functions. Marijuana affects the cerebellum, resulting in impairments in coordination of motor behavior and reaction time. Students will search the Internet and other sources for more information about the role and function of the cerebellum and will make a list of ways that disrupting the function of the cerebellum would affect their day-to-day behavior.
- English DrugPub ID:PHD712Publication from NIDA:Yes
- October 20, 2014
You already know the dangers of using marijuana before driving: Marijuana seriously impairs your motor skills and clouds your perception and judgment, all of which you need to safely operate a car. That’s why it’s illegal to drive high. But lots of people don’t know this … or they know it, but figure it’s okay “just this one time.” Whatever the case, it’s breaking the law, just like driving after drinking alcohol.
Driving under the influence of marijuana is a big problem. A 2007 study by the National Highway Transportation Safety Administration found that 8.7 percent of people driving at night on a weekend had been using marijuana—4 times the percentage of drivers who had had enough alcohol to impair them.
With all of these drugged drivers, police need an easy test to check if people have been using marijuana, like they have for alcohol. Unfortunately, there isn’t one—yet.
A Marijuana Breathalyzer
With alcohol, police can test a driver’s breath and tell if the person has enough in their system to impair their driving—a device called a breathalyzer. This works because alcohol leaves the body quickly. This also means that the breathalyzer only measures alcohol that has been recently used.
Measuring marijuana, however, turns out to be way, way more complicated.
For one thing, marijuana can stick around in a person’s body a lot longer than alcohol. It can be detected in blood tests of heavy users as much as a month after they’ve stopped using it! So in theory, heavy marijuana users could test positive in a blood test for marijuana even if they haven’t used it in a few weeks.
Another tricky thing with marijuana is that, after taking it, frequent users may show a higher amount of THC (marijuana’s active ingredient) in their body fluids than infrequent users do, even if the effect on their driving abilities is similar.
This means there’s a big need for a test that can universally tell when a person has consumed marijuana during the previous few hours, when it can have its biggest impact on driving ability—whether or not he or she uses the drug frequently or just occasionally. It also needs to be easy to use by police and painless for drivers.
Scientists are hard at work on the problem, and last fall a team of researchers at NIDA’s Intramural Research Program had a breakthrough: a first successful test of a marijuana breathalyzer.
Getting High for Science
In their research study, the scientists had a group of frequent marijuana-using adults and a comparison group of occasional marijuana-using adults each smoke a single marijuana cigarette (with an exactly measured dose of THC) and then provide breath samples using a device called SensAbues. Both groups tested positive up to an hour later, and frequent users tested positive 2 hours later.
So far it’s not perfect, and even though the collection device is very portable, the equipment to test the results isn’t, so there are still some hurdles. But it’s one step closer to making the roads safer from drugged drivers.
Tell us what you think in comments: Do you think if the police had a marijuana breath test, it would deter people from using marijuana before driving?
Check out these PSAs from Colorado reminding residents that while recreational use of marijuana is legal—driving under the influence of marijuana is illegal.
You may have heard it called pot, weed, grass, ganja, or skunk, but marijuana by any other name is still a drug that affects the brain.Spanish DrugPub ID:mi100sEnglish DrugPub ID:mi106
- March 05, 2015
In Part 1, we showed how the cannabis (hemp) plant spread from Asia to other parts of the world thousands of years ago, mainly because of its usefulness as a fiber and a grain. But as in ancient times, today some people used it for healing and some used it as a recreational drug. Now we’ll look at cannabis in America from Colonial times until the start of the 20th century, and lay to rest one of the biggest myths about the history of this drug.
Did the Founding Fathers Smoke It?
The cannabis or hemp plant has been an important source of grain and fiber for thousands of years. It was brought to North and South America by European colonists in the 1500s. Hemp fiber was widely used for making sails, rope, clothing, paper, and other valuable commodities, and the growing of hemp was encouraged by the American colonies.
There is a popular story you might have heard that the Founding Fathers of our nation smoked hemp. You might even see Thomas Jefferson quoted as saying: "Some of my finest hours have been spent on my back veranda, smoking hemp and observing as far as my eye can see."
In fact, that quote is completely made up. None of his writings include it (or anything like it); it was falsely attributed to him—no doubt by a marijuana fan—in recent times, and it has lived a life of its own on the Internet along with lots of other made-up “facts.”
Jefferson, along with George Washington and Benjamin Franklin, did grow hemp on their farms, as did most people who owned land, but there’s no direct evidence they ever smoked it. The amount of the psychoactive (mind-altering) chemical THC in most hemp at the time was probably too low anyway to become intoxicated from it. When Colonial Americans smoked anything, it was mainly tobacco—the drug that was also a big part of America’s economy during those times.
Cannabis From the Druggist
Cannabis was not widely used recreationally in the United States until the 20th century, but in the 1800s it was used as a medicine. In the 1830s, an Irish doctor in India found that cannabis extracts (not the smoked kind) could lessen the terrible vomiting of people suffering from the often fatal disease cholera. His discovery spread, and by the late 1800s, cannabis extracts were commonly sold by American druggists (pharmacists) for ailments, including stomach problems.
Using cannabis extracts to treat digestive symptoms makes some sense, scientifically. We now know that THC is able to lessen nausea, as well as promote hunger, by interacting with areas of the brain that regulate those functions, like the brainstem and hypothalamus. Today, two FDA- approved THC-based drugs taken as pills are prescribed to treat the nausea caused by cancer chemotherapy and the loss of appetite that causes “wasting syndrome” in AIDS patients.
But 19th-century doctors and druggists also touted cannabis extracts as beneficial for a long list of other problems, ranging from cough, fever, rheumatism, asthma, and diabetes to venereal (sexually transmitted) diseases, like gonorrhea.
This was still before modern medicine, when lots of herbal products (and even animal products like oil made from rattlesnakes) were sold as “cures” for every disease under the sun. These products were usually ineffective, occasionally harmful, and frequently (as with cannabis and opium extracts) even abused.
In 1906, Congress passed the Pure Food and Drug Act, requiring that cannabis and other herbal products be accurately labeled. This was the beginning of laws regulating the sale of cannabis. In later years, some states passed more restrictive laws on cannabis-based medicines as more and more people realized that they could be habit-forming.
Stay tuned for the final installment of our History of Marijuana series, and find out how cannabis started to be called marijuana.
Es posible que la hayas oído llamar "yerba", "mota", "mafu", "pasto", "maría" y "café" en español, o "pot", "weed", "grass", "ganja" y "skunk" en inglés. Sin embargo, no importa cómo la llames, la marihuana sigue siendo una droga que afecta al cerebro.Spanish DrugPub ID:mi100sEnglish DrugPub ID:mi106
What is marijuana
Marijuana refers to the dried leaves, flowers, stems, and seeds from the hemp plant, Cannabis sativa. The plant contains the mind-altering chemical delta-9-tetrahydrocannabinol (THC) and other related compounds. Extracts with high amounts of THC can also be made from the cannabis plant (see "Marijuana Extracts").
Marijuana is the most commonly used illicit drug in the United States (SAMHSA, 2014). Its use is widespread among young people. According to a yearly survey of middle and high school students, rates of marijuana use have steadied in the past few years after several years of increase. However, the number of young people who believe marijuana use is risky is decreasing (Johnston, 2014).
Legalization of marijuana for medical use or adult recreational use in a growing number of states may affect these views. Read more about marijuana as medicine in DrugFacts: Is Marijuana Medicine? at www.drugabuse.gov/publications/drugfacts/marijuana-medicine.
How do people use marijuana?
People smoke marijuana in hand-rolled cigarettes (joints) or in pipes or water pipes (bongs). They also smoke it in blunts—emptied cigars that have been partly or completely refilled with marijuana. To avoid inhaling smoke, more people are using vaporizers. These devices pull the active ingredients (including THC) from the marijuana and collect their vapor in a storage unit. A person then inhales the vapor, not the smoke.
Users can mix marijuana in food (edibles), such as brownies, cookies, or candy, or brew it as a tea. A newly popular method of use is smoking or eating different forms of THC-rich resins (see "Marijuana Extracts").
Smoking THC-rich resins extracted from the marijuana plant is on the rise. Users call this practice dabbing. People are using various forms of these extracts, such as:
- hash oil or honey oil—a gooey liquid
- wax or budder—a soft solid with a texture like lip balm
- shatter—a hard, amber-colored solid
These extracts can deliver extremely large amounts of THC to users, and their use has sent some people to the emergency room. Another danger is in preparing these extracts, which usually involves butane (lighter fluid). A number of people who have used butane to make extracts at home have caused fires and explosions and have been seriously burned.
How does marijuana affect the brain?
Marijuana has both short- and long-term effects on the brain.
When a person smokes marijuana, THC quickly passes from the lungs into the bloodstream. The blood carries the chemical to the brain and other organs throughout the body. The body absorbs THC more slowly when the person eats or drinks it. In that case, the user generally feels the effects after 30 minutes to 1 hour.
THC acts on specific brain cell receptors that ordinarily react to natural THC-like chemicals in the brain. These natural chemicals play a role in normal brain development and function.
Marijuana overactivates parts of the brain that contain the highest number of these receptors. This causes the "high" that users feel. Other effects include:
- altered senses (for example, seeing brighter colors)
- altered sense of time
- changes in mood
- impaired body movement
- difficulty with thinking and problem-solving
- impaired memory
Marijuana also affects brain development. When marijuana users begin using as teenagers, the drug may reduce thinking, memory, and learning functions and affect how the brain builds connections between the areas necessary for these functions.
Marijuana’s effects on these abilities may last a long time or even be permanent.
For example, a study showed that people who started smoking marijuana heavily in their teens and had an ongoing cannabis use disorder lost an average of eight IQ points between ages 13 and 38. The lost mental abilities did not fully return in those who quit marijuana as adults. Those who started smoking marijuana as adults did not show notable IQ declines (Meier, 2012).
A Rise in Marijuana’s THC Levels
The amount of THC in marijuana has been increasing steadily over the past few decades (Mehmedic, 2010). For a new user, this may mean exposure to higher THC levels with a greater chance of a harmful reaction. Higher THC levels may explain the rise in emergency room visits involving marijuana use.
The popularity of edibles also increases the chance of users having harmful reactions. Edibles take longer to digest and produce a high. Therefore, people may consume more to feel the effects faster, leading to dangerous results.
Dabbing is yet another growing trend. More people are using marijuana extracts that provide stronger doses, and therefore stronger effects, of THC (see "Marijuana Extracts").
Higher THC levels may mean a greater risk for addiction if users are regularly exposing themselves to high doses.
What are the other health effects of marijuana?
Marijuana use may have a wide range of effects, both physical and mental.
- Breathing problems. Marijuana smoke irritates the lungs, and frequent marijuana smokers can have the same breathing problems that tobacco smokers have. These problems include daily cough and phlegm, more frequent lung illness, and a higher risk of lung infections. Researchers still do not know whether marijuana smokers have a higher risk for lung cancer.
- Increased heart rate. Marijuana raises heart rate for up to 3 hours after smoking. This effect may increase the chance of heart attack. Older people and those with heart problems may be at higher risk
- Problems with child development during and after pregnancy. Marijuana use during pregnancy is linked to increased risk of both brain and behavioral problems in babies. If a pregnant woman uses marijuana, the drug may affect certain developing parts of the fetus’s brain. Resulting challenges for the child may include problems with attention, memory, and problem-solving. Additionally, some research suggests that moderate amounts of THC are excreted into the breast milk of nursing mothers. The effects on a baby’s developing brain are still unknown.
Long-term marijuana use has been linked to mental illness in some users, such as:
- temporary hallucinations—sensations and images that seem real though they are not
- temporary paranoia—extreme and unreasonable distrust of others
- worsening symptoms in patients with schizophrenia (a severe mental disorder with symptoms such as hallucinations, paranoia, and disorganized thinking)
Marijuana use has also been linked to other mental health problems, such as:
- suicidal thoughts among teens
Is marijuana addictive?
Contrary to common belief, marijuana can be addictive. Research suggests that about 1 in 11 users becomes addicted to marijuana (Anthony, 1994; Lopez-Quintero 2011).This number increases among those who start as teens (to about 17 percent, or 1 in 6) and among people who use marijuana daily (to 25-50 percent) (Hall, 2009a; Hall, 2009b).
How Does Marijuana Affect a User’s Life?
Compared to nonusers, heavy marijuana users more often report the following:
- lower life satisfaction
- poorer mental health
- poorer physical health
- more relationship problems
Users also report less academic and career success. For example, marijuana use is linked to a higher likelihood of dropping out of school (McCaffrey, 2010). It is also linked to more job absences, accidents, and injuries (Zwerling, 1990).
How can people get treatment for marijuana addiction?
Long-term marijuana users trying to quit report withdrawal symptoms that make quitting difficult. These include:
- decreased appetite
Behavioral support has been effective in treating marijuana addiction. Examples include therapy and motivational incentives (providing rewards to patients who remain substance free). No medications are currently available to treat marijuana addiction. However, continuing research may lead to new medications that help ease withdrawal symptoms, block the effects of marijuana, and prevent relapse.
Points to Remember
- Marijuana refers to the dried leaves, flowers, stems, and seeds from the hemp plant, Cannabis sativa.
- The plant contains the mind-altering chemical delta-9-tetrahydrocannabinol (THC) and other related compounds.
- People use marijuana by smoking, eating, drinking, and inhaling it.
- Smoking THC-rich extracts from the marijuana plant (a practice called dabbing) is on the rise.
THC overactivates certain brain cell receptors, resulting in effects such as:
- altered senses
- changes in mood
- impaired body movement
- difficulty with thinking and problem-solving
- impaired memory and learning
Marijuana use may have a wide range of effects, both physical and mental, which include:
- breathing illnesses
- possible harm to a fetus’s brain in pregnant users
- hallucinations and paranoia
- The amount of THC in marijuana has been increasing steadily, creating more harmful effects for users.
- Marijuana can be addictive.
- Treatment for marijuana addiction includes forms of behavioral therapy. No medications currently exist for treatment.
For more information on marijuana and marijuana use, visit:
For more information on marijuana as medicine and on state laws related to marijuana, visit:
Monitoring the Future
Learn more about the Monitoring the Future survey, which annually measures drug, alcohol, and tobacco use and related attitudes among teenage students nationwide:
This publication is in the public domain and may be used or reproduced in its entirety without permission from NIDA. Citation of the source is appreciated.
Anthony J, Warner LA, Kessler RC. Comparative epidemiology of dependence on tobacco, alcohol, controlled substances, and inhalants: basic findings from the National Comorbidity Survey. Exp Clin Psychopharmacol. 1994;2:244-268.
Hall W, Degenhardt L. Adverse health effects of non-medical cannabis use. Lancet. 2009;374:1383-1391.
Hall W. The adverse health effects of cannabis use: what are they, and what are their implications for policy? Int J of Drug Policy. 2009;20:458-466.
Johnston LD, O’Malley PM, Miech RA, Bachman JG, Schulenberg JE. Monitoring the Future national results on drug use: 1975-2014: Overview, Key Findings on Adolescent Drug Use. Ann Arbor, MI: Institute for Social Research, The University of Michigan; 2014.
Lopez-Quintero C, Pérez de los Cobos J, Hasin DS, et al. Probability and predictors of transition from first use to dependence on nicotine, alcohol, cannabis, and cocaine: results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Drug Alcohol Depend. 2011;115(1-2):120-130.
McCaffrey DF, Pacula RL, Han B, Ellickson P. Marijuana use and high school dropout: the influence of unobservables. Health Econ. 2010;19(11):1281-1299.
Mehmedic Z, Chandra S, Slade D, et al. Potency trends of Δ9-THC and other cannabinoids in confiscated cannabis preparations from 1993 to 2008. J Forensic Sci. 2010;55(5):1209-1217.
Meier MH, Caspi A, Ambler A, et al. Persistent cannabis users show neuropsychological decline from childhood to midlife. Proc Natl Acad Sci USA. 2012;109:E2657-2664.
Substance Abuse and Mental Health Services Administration (SAMHSA). Results from the 2013 National Survey on Drug Use and Health: Summary of National Findings. Rockville, MD: Substance Abuse and Mental Health Services Administration; 2014. HHS Publication No. (SMA) 14-4887. NSDUH Series H-49.
Zwerling C, Ryan J, Orav E. The efficacy of preemployment drug screening for marijuana and cocaine in predicting employment outcome. JAMA. 1990;264(20):2639-2643.Publication from NIDA:Yes
- October 27, 2014
As more communities allow medical marijuana, or decriminalize illicit marijuana, veterinarians are seeing an alarming trend. More and more dogs are arriving in emergency animal hospitals with marijuana toxicosis, or marijuana poisoning.
A recent study in Colorado showed that 4 times as many dogs were treated for marijuana poisoning in 2010 than in 2005. Sadly, two dogs identified in that study died. Similarly, from 2008 to 2013, the Pet Poison Helpline—a poison control hotline for animals—has seen a 200% increase in calls related to pets eating marijuana.
Most times, dogs ingest marijuana accidentally by eating a marijuana “edibles,” such as cookies or brownies, or getting into their owner’s supply. However, there are some instances where people deliberately give marijuana to their dogs or blow marijuana smoke in their faces to “get them high.” Maybe that sounds funny to people that are high, but it is very dangerous for their dog.
While it is rare that a dog will die from marijuana poisoning, serious medical issues such as injury or dehydration can occur. Marijuana can cause dogs to become disoriented and lose coordination, leading to missteps and falls, even to the point they can’t drink water from their bowl. Symptoms of marijuana poisoning in dogs include anxiety, panting, lethargy, impaired balance (staggering or being unable to walk), drooling, vomiting, diarrhea, trembling, or extreme responses to noises, movements, or other stimulus.
So, the next time you see one of those “dogs high on weed” videos on YouTube, give it a thumbs down. And be sure to keep your furry friends away from marijuana. Even if you believe in free choice when it comes to marijuana, you can agree that animals aren’t being given a choice when marijuana is carelessly left out for them to eat or when owners expose them for kicks. Even unintentional exposure from secondhand smoke can be harmful.
While the debate continues about the usefulness of medical marijuana, some veterinarian groups are looking at using compounds found in the marijuana plant for animals. However, those compounds would be carefully tested and monitored by medical professionals and have no relationship to careless exposure to helpless pets.
Tell us in comments: What would you do if you knew someone was exposing their dog or other pets to marijuana?
Hi, my name is Sara Bellum. Welcome to my magazine series exploring the brain's response to drugs. In this issue, we'll investigate the fascinating facts about marijuana.
You may have heard it called pot, weed, grass, ganja or skunk, but marijuana by any other name is still a drug that affects the brain.
Did you know marijuana can have different effects on different people? For example, it can cause some people to lose focus on things around them. It makes others more aware of their senses—like sight, sound, smell, and taste, and it has still different effects on other people.
All these changes are caused by chemicals that affect the brain. More than 400 chemicals are in the average marijuana plant. When smoked, heat produces even more of them!
- April 02, 2015
On this blog, we often get comments from people claiming that marijuana isn’t addictive. A lot of people seem to think marijuana is different from other drugs. Unfortunately, it’s not the case: Just like with other drugs (including alcohol and nicotine), you can get addicted to marijuana—especially if you use it during your teen years.
Dependence vs. Addiction
Dependence means needing a drug to feel physically okay. It doesn’t necessarily mean you are addicted—for example, many people can be dependent on a prescribed medication without being addicted. The difference is that people that are addicted start to think about the drug all the time and make it a higher priority than other things in their life; they often make bad decisions that work against their health and their overall well-being. In the case of a medication, they may start to abuse it (using it differently than how the doctor has prescribed) by taking more of it or crushing it and injecting it. Or in the case of a drug like marijuana, they will be unable to stop using it even though it is causing problems with school, jobs, or relationships. People with addictions are often unable to see—or admit—that this is happening.
One part (but not the only part) of being addicted to a drug is needing the drug to feel physically okay—a condition that is called dependence (see box, “Dependence vs. Addiction”). A person with dependence feels bad when they don’t have the drug, and having enough of a supply is always important to them.
That Bad Feeling …
… is called withdrawal. It’s what leads a lot of people who are addicted to a drug to relapse—meaning, they have tried to quit, but start taking the drug again.
A new study in the Journal of Addiction Medicine shows that teens who use marijuana heavily can experience withdrawal when they stop using it. In a study of teens receiving drug abuse treatment at an outpatient clinic, nearly half of them (40 percent) experienced symptoms of withdrawal when they stopped using marijuana.
Not Just a Crummy Day
From portrayals in movies and on TV of people addicted to heroin, people have an image of drug withdrawal as sweating, shaking, and being curled up in bed with unbearable pain. Marijuana withdrawal is a lot more subtle, but every bit as real.
The main mental symptoms of marijuana withdrawal include:
- Being irritable
- Feeling anxious or worried
- Feeling depressed
- Being restless
- Having trouble sleeping at night and feeling tired during the day
- Having low appetite or losing weight
Some people having marijuana withdrawal might not realize it. Some of the symptoms just contribute to being in a lousy mood, and it’s often easy to blame that feeling on other people annoying you or just having a bad day. You can also have physical symptoms like:
- Stomach pain
The longer a person uses marijuana, the more likely they are to have withdrawal symptoms when they aren’t using it. And teen users who suffer marijuana withdrawal are more likely to experience marijuana addiction than adults. One in six teens who try marijuana will get addicted to it, and that goes up to as many as one-half of teens who use it every day.
In the Journal of Addiction Medicine study, teens who had marijuana withdrawal symptoms were more likely than other marijuana users to have problems like difficulties at school or at work or trouble with relationships or money. They were also more likely to have other signs of marijuana dependence and mood disorders like depression.
If you’re worried you may have a problem with marijuana or any other drug, this page may help answer your questions and let you know what to do to get help.
Tell us in comments: Do you know any regular marijuana users who stop using marijuana and experience the withdrawal symptoms described in this post?
Me llamo Clara Mente y quiero darles la bienvenida a mi serie de boletines informativos que exploran la respuesta del cerebro a las drogas. En este ejemplar, investigaremos varios datos fascinantes sobre la marihuana. Alguna de esta información fue descubierta recientemente por los científicos que lideran la investigación en este campo.
Es posible que la hayas oído llamar "yerba", "mota", "mafu", "pasto", "maría" y "café" en español, o "pot", "weed", "grass", "ganja" y "skunk" en inglés. Pero no importa cómo la llames, la marihuana es una droga que afecta al cerebro.
¿Sabías que la marihuana puede hacer que algunas personas no se den cuenta de lo que está pasando alrededor de ellos? En cambio, a otros los hace más conscientes de las sensaciones físicas y tiene aún efectos diversos en otras personas.
Todos estos diferentes cambios son causados por sustancias químicas que afectan al cerebro. En promedio, existen más de 400 sustancias químicas en una planta corriente de marihuana. Cuando se la fuma, el calor hace producir aún más sustancias químicas.
2014’s Monitoring the Future survey of drug use and attitudes among American 8th, 10th, and 12th graders continued to show encouraging news about youth drug use, including decreasing use of alcohol, cigarettes, and prescription pain relievers; no increase in use of marijuana; decreasing use of inhalants and synthetic drugs, including K2/Spice and bath salts; and a general decline over the last two decades in the use of illicit drugs. However, the survey highlighted growing concerns over the high rate of e-cigarette use and softening of attitudes around some types of drug use, particularly decreases in perceived harm and disapproval of marijuana use.
The 2014 survey showed continued declines in alcohol use by all grades. Nine percent of 8th graders, 23.5 percent of 10th graders, and 37.4 percent of 12th graders reported past-month use of alcohol, which was significantly lower than in 2009, when rates were 14.9 percent, 30.4 percent, and 43.5 percent, respectively. There was also a significant five-year drop in binge drinking (five or more drinks in a row in the previous 2 weeks) by seniors: 19.4 percent reported binge drinking in 2014, whereas 31.5 percent had reported the practice at its peak in 1998.
Tobacco and e-Cigarettes
Cigarette smoking by youth continues to drop and is currently at its lowest rate in the survey’s history. Only 1.4 percent of 8th graders reported smoking every day in 2014, compared to 2.7 percent in 2009; 3.2 percent of 10th graders reported smoking daily, compared to 4.4 percent in 2013 and 6.3 percent in 2009; and 6.7 percent of high school seniors reported smoking daily in 2014, down from 8.5 percent in 2013 and 11.2 percent in 2009. In 1997, at its peak, nearly a quarter of seniors were daily smokers.
However, other forms of tobacco remain popular. In 2014, past-year hookah use continued to increase among 12th graders to 22.9 percent—the highest rate since 2010, when the survey started capturing this type of tobacco use.
Also popular among teens is the use of e-cigarettes, which was measured for the first time in 2014. Use of e-cigarettes in the past 30 days was reported by 8.7 percent of 8th graders, 16.2 percent of 10th graders, and 17.1 percent of 12th graders. Only 14.2 percent of 12th graders view regular e-cigarette use as harmful. The nicotine in e-cigarettes is vaporized and inhaled (not smoked), but the health impact of e-cigarette use is not yet clear, nor do we know if e-cigarette use makes it more likely for people to use conventional cigarettes or other tobacco products. Survey findings show that while most e-cigarette users have also smoked conventional tobacco products, approximately 2.9 percent of 8th graders, 4.5 percent of 10th graders, and 3.8 percent of 12th graders who report past month use of e-cigarettes deny ever using tobacco cigarettes or smokeless tobacco.
Use of any illicit drug has generally declined over the past two decades. Past-year use of illicit drugs for all grades combined was 27.2 percent in 2014, down from its peak at 34.1 percent in 1997. The MTF survey also shows a decline in the perceived availability of most substance over the past few years, including alcohol, cigarettes, marijuana, powder cocaine, crystal methamphetamine, and prescription painkillers.
Marijuana use remained stable in 2014, even though the percentage of youth perceiving the drug as harmful went down. Past-month use of marijuana remained steady among 8th graders at 6.5 percent, among 10th graders at 16.6 percent, and among 12th graders at 21.2 percent. Close to 6 percent of 12th graders report daily use of marijuana (similar to 2013), and 81 percent of them said the drug is easy to get. Among 8th graders, there was a drop in perceived availability in 2014, with 36.9 percent saying it is easy to get marijuana, compared to 39.1 percent in 2013.Percent of Students Reporting Use of Marijuana in Past YearSource: University of Michigan, 2014 Monitoring the Future Study
Although marijuana use has remained relatively stable over the past few years, there continues to be a shifting of teens’ attitudes about its perceived risks. The majority of high school seniors do not think occasional marijuana smoking is harmful, with only 36.1 percent saying that regular use puts the user at great risk, compared to 39.5 percent in 2013 and 52.4 percent in 2009. However, 56.7 percent of seniors say they disapprove of adults who smoke it occasionally, and 73.4 percent say they disapprove of adults smoking marijuana regularly.Percent Perceiving Great Risk of Smoking Marijuana RegularlySource: University of Michigan, 2014 Monitoring the Future Study
Marijuana use continues to exceed cigarette use in all three grade levels. In 2014, 21.2 percent of high school seniors had used marijuana in the past 30 days, whereas only 13.6 percent had smoked cigarettes.
Prescription and Over-the-Counter Drugs
Misuse and abuse (or “non-medical use”) of prescription and over-the-counter drugs continues to decline among the nation’s youth. Past-year use of the opioid pain reliever Vicodin has dropped significantly over the past 5 years; 4.8 percent of 12th graders used Vicodin for non-medical reasons in 2014, compared to 9.7 percent in 2009. Past-year use of narcotics other than heroin (which includes all opioid pain relievers) among high school seniors dropped from 7.1 percent in 2013 to 6.1 percent in 2014; 9.5 percent of seniors had reported past-year use of these drugs in 2004.
Past-year non-medical use of the stimulants Adderall and Ritalin (often prescribed for ADHD) remained relatively steady in 2014, at 6.8 percent and 1.8 percent respectively for high school seniors. The survey continues to show that most teens get these medicines from friends or relatives; a smaller percentage misuse or abuse pills that had been prescribed for them for a medical problem. Although teens did not misuse or abuse prescription stimulants at higher rates than in past years, there has been a decline in teens’ perceptions the risks of doing so. In 2014, 55.1 percent of seniors saw regularly taking prescription amphetamines as harmful, down from 69.0 percent in 2009.
In 2014, there was also a significant drop in the past-year use of cough/cold medicines containing dextromethorphan (DXM) among 8th graders, with only 2.0 percent using them for non-medical reasons, down from 2.9 percent in 2013 and 3.8 percent in 2009.
Other Illicit Drugs
Past-year use of MDMA (also known as ecstasy or “Molly”) saw a significant decline among 10th graders to 2.3 percent in 2014, from 3.6 percent in 2013 and 6.2 percent in 2001, when it peaked. Past-year use of heroin remained very low in all three grades despite increased use among adults over 26 years of age in 2013.1
There has been a considerable decline in past-year use of synthetic cannabinoids (“K2/Spice,” sometimes misleadingly called “synthetic marijuana”) in the two years the survey has been tracking their use. Only 5.8 percent of 12th graders reported using K2/Spice in 2014, compared to 7.9 percent in 2013 and 11.3 percent in 2012. This was associated with an increase in the perceived risk of taking synthetic marijuana once or twice among 12th graders. Use of the hallucinogen salvia also dropped significantly among 12th graders in 2014 to 1.8 percent, from 3.4 percent in 2013.
Another harmful synthetic drug, bath salts (synthetic stimulants), was added to the survey in 2012; past-year use of bath salts remained low in 2014, and dropped considerably among 8th graders, to 0.5 percent, compared to 1 percent.
Current, past-year, and lifetime use of inhalants among 10th and 12th graders is at its lowest levels in the history of the survey. Rates of inhalant use are traditionally highest among the youngest adolescents (unlike most other drugs); in 2014, 5.3 percent of 8th graders reported using inhalants in the past year, down from 8.1 percent in 2009 and 12.8 percent in 1995, when use peaked.
Complete MTF survey results are available at www.monitoringthefuture.org.
For more information on the survey and its findings, also visit www.drugabuse.gov/related-topics/trends-statistics/monitoring-future.
About the Survey
Since 1975, the MTF survey has meas-ured drug, alcohol, and cigarette use and related attitudes among 12th graders, nationwide. In 1991, 8th and 10th graders were added to the survey. Survey participants report their drug use behaviors across three time peri-ods: lifetime, past year, and past month. Overall, 41,551 students from 377 public and private schools in the 8th, 10th, and 12th grades participated in the 2014 survey.
The survey is funded by NIDA and con-ducted by the University of Michigan. Results from the survey are released each December.
Other sources of information on drug use trends among youth are available:
The annual National Survey on Drug Use and Health, conducted by the Substance Abuse and Mental Health Services Administration, gathers detailed data on drug, alcohol, and tobacco use by all age groups. It is a comprehensive source of information on substance use and dependence among Americans aged 12 and older. Data and reports can be found at www.samhsa.gov/data/population-data-nsduh.
The Youth Risk Behavior Survey is a school-based survey conducted every other year by the Centers for Disease Control and Prevention. It gathers data on a wide variety of health-related risk behaviors, including drug abuse, from students in grades 9 through 12. More information is available at www.cdc.gov/nccdphp/dash/yrbs/index.htm.
Associated Drug of Abuse:Publication from NIDA:Yes
- Substance Abuse and Mental Health Services Administration. Results from the 2013 National Survey on Drug Use and Health: Summary of national findings. Rockville, MD: Substance Abuse and Mental Health Services Administration; 2014. HHS Publication No. (SMA) 14-4887. NSDUH Series H-49.
- November 03, 2014
Not many people would say with a straight face that drugs like heroin or methamphetamine are good for you, let alone they could help you be more successful in life. But there are lots of people who think marijuana is different from other drugs. For example, we’ve already talked in this blog about the idea that it may have medical uses. The jury is still out.
Some users even say marijuana’s mind-altering effect—the “high”—is also beneficial. They claim using the drug chills them out, expands their mind, and makes them more creative. Since the 1960s, marijuana has had a mystique as an aid to the artistic life.
What does science say?
Many studies over the years have found that marijuana indeed makes users perceive themselves as having more creative thoughts and ideas—which would help explain why so many artists and musicians tout its benefits.
But perception isn’t always the same as reality—and we know that marijuana alters perceptions. In fact, the research on cannabis and creativity suggests that even if users feel more creative, it’s actually an illusion. People may even be less creative after using it.
For example, a new study of almost 60 cannabis users in The Netherlands looked at the effects of the drug on a measure of creativity called divergent thinking—which means the ability to brainstorm, think flexibly, and come up with original solutions to problems. After inhaling a high or low dose of vaporized cannabis or a vapor with the same odor and taste but no THC (the chemical that causes the high), the participants took a test that asked them to come up with as many creative uses for two common items (like a pen or a shoe) as they could.
The results surprised even the researchers: Low doses of cannabis did not have any effect on the participants’ ability to think creatively, compared to not taking cannabis. And high doses actually lowered their creativity—by a lot.
It seems that feeling creative and being creative really aren’t the same thing.
Yet it is also true that your expectations about a drug do matter. Different studies have shown that people who are unknowingly given a placebo instead of a drug (or alcohol) will act or perform in ways that correspond to how they expect the drug to affect them.
Marijuana on Your Mind
One study, for example, found that regular marijuana users who ate biscuits containing marijuana were less creative than a control group who didn’t eat any biscuits, and that both of those groups were less creative than a group who ate biscuits they thought contained marijuana but were actually a placebo.
It goes to show that your mind, including your beliefs about drugs, have a lot more power than you think. You don’t have to take the drug to get the effect you expect—in fact it works best if you don’t!
What do you think? Do you know people who take marijuana (or other drugs) to help them be more creative? Do you think it helps or hurts them? Let us know in comments.
Marijuana is the dried leaves and flowers of the hemp plant (Cannabis sativa). Like all plants it's sensitive to the environment where it grows.
Different weather and soil conditions can change the amounts of the chemicals inside the plant. That means marijuana grown in a place like Hawaii might be chemically different than marijuana from Mexico or vice-versa.
How does marijuana affect nerve cells in the brain?
Marijuana interferes with some parts of the brain—such as those affecting emotions, memory and judgment—to lose balance and controoooooooooooooooooooooooolllllllll.
- June 02, 2015
You may know that smoking marijuana can pose risks for a person’s physical health and brain development, especially for teens. But did you know that, for some people, it carries risks for their mental health, too?
We don’t just mean short-term memory problems or poor judgment—those can happen for anybody who smokes marijuana. We’re talking about serious mental illness.
Researchers have found that some marijuana users have an increased risk for psychosis, a serious mental disorder where people have false thoughts (delusions) or see or hear things that aren’t there (hallucinations). But there is still a lot to learn about whether marijuana use may lead to this loss of touch with reality, or if having a mental illness makes people more likely to use marijuana. And as with other drugs, things like the age of users, how early they started smoking pot, the amount of the drug they used, and their genetics all could make a difference in whether or not long-term problems develop.
It’s not your jeans that matter—it’s your genes
Regular marijuana users with a specific version of a particular gene, AKT1, are at a greater risk of developing psychosis than those who smoke it less often or not at all. How much greater? For people who smoke marijuana daily, the risk is up to seven times greater.
The reason is that the AKT1 gene affects how much dopamine is released in your brain. Dopamine is one of our brain’s “feel-good” chemicals; it affects important brain functions such as behavior, motivation, and reward. When your brain releases dopamine (for example, after a beautiful bike ride or when you eat a delicious piece of chocolate), the release “teaches” your brain to seek out the same experience (reward) again. Some researchers believe that changes in dopamine levels are linked to psychosis.
Another study found that adults who used marijuana when they were teenagers and who carried a specific form of another gene for the enzyme COMT (which also impacts dopamine signaling) were at a higher risk of becoming psychotic.
Are you at risk?
Right now, unless you’ve had your DNA tested for those specific genes, you don’t know. Many health professionals believe that in the future most of us will know much more about our genetic makeup, but for now and for regular marijuana users, it’s an unknown risk—and you won’t know until you've developed an addiction.
Even if you don’t have those specific genes, there’s still a risk
A psychotic event can even happen to pot smokers without these specific genes that put them at risk for long-term serious mental illness. Although rare, marijuana-induced psychosis is becoming more common as people use higher potency forms, including edibles and oil extracts.
The bottom line? It’s important to know all the risks that can come with using marijuana.Categories:Brain Science
¿De qué manera las sustancias químicas de la marihuana cambian la forma en que una persona ve, oye, huele, gusta y siente las cosas?
Cuando alguien usa marihuana, sus sustancias químicas viajan a través del torrente sanguíneo al cerebro y rápidamente se adhieren a lugares especiales en las células nerviosas (neuronas) del cerebro. Estos lugares se llaman receptores, porque reciben información de otras células nerviosas y de sustancias químicas. Cuando un receptor recibe información, produce cambios en la célula nerviosa.
La sustancia química en la marihuana que tiene un gran impacto sobre el cerebro se llama THC — tetrahidrocanabinol. (¡Qué bárbaro! Trata de decir eso diez veces rápidamente). Recientemente, los científicos descubrieron que algunas áreas del cerebro tienen muchos receptores de THC, mientras que otras tienen muy pocos o ninguno. Estas pistas están ayudando a los investigadores a descifrar exactamente cómo el THC trabaja en el cerebro.
La marihuana produce efectos en varias partes
- ¿Qué sabes sobre los efectos en los latidos del corazón? ¿Hasta cuántos latidos por minuto se puede acelerar? ¿Hasta 100, 130 ó 160?
- Los efectos en los vasos sanguíneos. ¿En qué parte del cuerpo se los pueden observar? ¿En la cara, los ojos o los pies?
- Las sensaciones que acompañan al pánico. ¿Sudoración, boca seca, dificultades para respirar o todas ellas?
- La tos diaria y la congestión de pecho. ¿A las de quiénes se parecen? ¿A las de los fumadores de tabaco, trabajadores de construcción o personas mayores?
- La marihuana puede acelerar el ritmo cardiaco hasta 160 latidos por minuto.
- Los vasos sanguíneos se pueden dilatar y esto hace que los ojos se pongan rojos.
- La sensación de pánico se acompaña de sudoración, boca seca y dificultad para respirar.
- A las de los fumadores de tabaco.
- Associated Drug of Abuse:Publication from NIDA:Yes
- November 10, 2014
Question: If you look at the candy in the check-out aisle in your local store, an average chocolate bar is 1 serving, and an average bag of candy-covered chocolates (which has about 30 candies) is also 1 serving.
What is the average serving of a marijuana edible chocolate bar or bag of a candy that has been infused with THC—the active ingredient in marijuana?
Answer: There is no average serving.
Yes, it was a trick question. But that’s kind of what marijuana edibles are…tricky. At least for a person who doesn’t use marijuana regularly.
For example, in Colorado, a single serving of an edible marijuana food product purchased for adult recreational use (as opposed to medicinal use) can’t have more than 10 milligrams of THC in it. BUT, there can be up to ten servings in the product or package. That means a single bag of marijuana candy, a marijuana chocolate bar, a marijuana brownie, or any other marijuana edible might contain as much as 100 milligrams of THC.
Smoking marijuana delivers to the user about 5 mg of THC in one puff. So if you ate all ten gummies in a bag of marijuana candy—each one a single 10 mg “serving”—it would be like taking 20 hits of a marijuana cigarette at one time! Because it takes longer to feel the effects of the THC when you eat an edible compared to smoking marijuana—up to an hour or two, this happens a lot. People end up eating more than the recommended serving because they don’t “feel” it right away.
But really, it also goes against how most people eat candy. When was the last time you just had one candy from a bag?
Beverages containing cannabis can be even more confusing. For example, one product contains 7.5 servings in a bottle that is about the same size as a can of soda. Does that mean that you are supposed to take only one sip? A sip and a half?
Manufacturers may say it’s a great drink to share, but do you really want to share a bottle with 7.5 friends? That’s a little too much sharing, if you ask us. (And how do you find half a friend?)
We all know that these THC-infused edibles and drinks are illegal for teens to use and buy. But many will find ways to try them. They may find, however, that it isn’t worth long nights coping with overwhelming dizziness, hallucinations, and stomach sickness (common symptoms of overdose)—and for a growing number of unlucky experimenters, trips to the emergency room.
That’s what happened to New York Times reporter Trish Reske’s 21-year-old son, who had to be rushed to the hospital after eating all 6 servings of a marijuana chocolate bar. Not a great way to spend an evening.
Tell us in comments: What should manufacturers do to make marijuana edibles safer?
How do the chemicals in marijuana change the way a person sees, hears, smells, tastes, and feels things?
When someone uses marijuana, these chemicals travel through the bloodstream and quickly attach to special places on the brain's nerve cells. These places are called receptors, because they receive information from other nerve cells. Chemicals carry this information, which changes the nerve cell receiving it.
One chemical in marijuana that has a big impact on the brain is called THC—tetrahydrocannabinol. (Whew! Try saying that 10 times fast.) Scientists have found that some areas of the brain have a lot of THC receptors, while others have very few or none. These clues are helping researchers figure out exactly how THC works in the brain.
Marijuana may cause some parts of the body to react in different ways.
What do you know about:
- Rapid Heartbeat—up to how many beats per minute? Is it 100, 130 or 160?
- Dilated blood vessels—can be seen in what part of the body? Is it the face, the eyes, the feet?
- A feeling of panic—accompanied by what kind of sensations? Is it sweating, dry mouth, breathing difficulties or all of these?
- Daily cough and more frequent chest colds very much like who? Is it tobacco smokers, construction workers or the elderly?
- Marijuana can speed the heart rate up to 160 beats per minute.
- Dilated blood vessels make the whites of the eyes turn red.
- Panic feelings may be accompanied by sweating, dry mouth and trouble breathing.
- Tobacco smokers.
Una región del cerebro que contiene muchos receptores de THC es el hipocampo, que es donde se procesa la memoria. Cuando el THC se adhiere a los receptores en el hipocampo, debilita la memoria de corto plazo.
El hipocampo también se comunica con otras regiones del cerebro que procesan información nueva para que ésta forme parte de la memoria a largo plazo. (Así es como te acuerdas de la lección de matemática de hoy o del número telefónico de un amigo nuevo). Cuando se está bajo la influencia de la marihuana, es posible que el cerebro nunca registre esta nueva información y se pierda de la memoria.
Tal vez hayas oído que en algunas personas la marihuana los puede hacer pasar rápidamente de una risa incontrolable un minuto a una paranoia el siguiente. Eso es porque el THC también influye en las emociones, probablemente actuando sobre una región del cerebro llamada el sistema límbico.
Y nunca te olvides de esto: el THC puede convertir algo tan sencillo como conducir un automóvil en algo verdaderamente peligroso.
Get an insider's look at the brains of mice on drugs.Default Image:Drug Facts:
- November 17, 2014
Do you know how long it took for tobacco smoking rates to significantly drop after researchers first linked smoking cigarettes to cancer? 40 years.
In the 1920s, when the link to cancer was discovered, smoking was normal---in fact, ads for cigarettes even featured doctors saying it relieved stress! For years, people smoked in their homes and offices, in restaurants and stores, on planes and on trains. Wherever they went…they smoked. In 1957, the nation’s top doctor—the U.S. Surgeon General—warned that cigarette smoking could cause lung cancer. Other government doctors began to speak out. Still, people continued to smoke.
Overtime, laws to protect the public’s health limiting where people could smoke, increases in the cost of cigarettes, and the growing body of evidence that smoking was directly linked to lung cancer helped lead turn the tide. Now, it’s surprising to find people smoking inside—it’s the norm for people to have to go outside.
Today, it is marijuana that people, especially younger people, are beginning to view as ‘okay’ or ‘less dangerous’ or ‘normal.’ It reminds us of tobacco nearly 100 years ago—and not in a good way.
A big difference, though, is for teens —we already know that using marijuana comes with some serious risks. Evidence is strong that smoking marijuana on a regular basis can harm the developing teen brain. And long-term, regular use of marijuana starting in the teen years can impair brain development and lower IQ. In other words, the brain may not reach its full potential.
As more and more states legalize marijuana for adults, it will likely be easier to get (even for teens), and there’s a chance that the number of people who use it will increase. For teens, this could have real and lasting effects. The question is, how long will it take before perception catches up to reality?
Scholastics shares the facts surrounding the great marijuana debate with its recent article, ‘Marijuana: Breaking Down the Buzz’.
Tell us in comments, is marijuana the next tobacco? Do these facts change your perception?
For additional facts about the brain and drugs, visit scholastic.com/headsup.
One region of the brain that contains a lot of THC receptors is the hippocampus, which usually helps with memory. When THC attaches to receptors in the hippocampus, it interferes with memory.
Researchers have also shown that heavy use of marijuana by young people can actually cause IQ to go down—and this change in IQ can last a long time and may even be permanent! This means that someone who uses marijuana may not do as well in school and may have trouble remembering things like their friend's phone number.
Maybe you've heard that marijuana can cause a range of emotions from uncontrollable laughter to paranoia. That's because THC also influences emotions, probably by acting on a region of the brain called the limbic system.
And don't forget this: THC can make something as simple as driving a car really dangerous.
Describes nationwide trends in drug abuse and addiction, focusing on past-month use for illicit drugs (including marijuana and prescription drugs), alcohol, and tobacco.Publication from NIDA:No
Algunos de los efectos del THC son útiles en el mundo de la medicina. Por ejemplo, para prevenir la náusea y bloquear el dolor. El truco está en que los científicos logren obtener estos resultados sin los efectos dañinos.
Los científicos han encontrado que el cerebro fabrica una sustancia química en el cuerpo humano llamada anandamida, que se adhiere a los mismos receptores en el cerebro donde se adhiere el THC. Este descubrimiento puede llevar al desarrollo de medicamentos químicamente similares al THC pero menos dañinos, que pueden ser usados para tratar la náusea y el dolor.
Explorando la Mente es una serie producida por el Instituto Nacional sobre el Abuso de Drogas (NIDA, por sus siglas en inglés), parte de los Institutos Nacionales de la Salud. Estos materiales son del dominio público y se pueden reproducir sin permiso. Se agradece citar la fuente.
Publicación NIH No. 06-3859 (s). Impresa en el 2006.
Instituto Nacional sobre el Abuso de Drogas
Institutos Nacionales de la Salud
Departamento de Salud y Servicios Humanos de los EE.UU.
Explore what happens to the brain on drugs.Default Image:Drug Facts:
- November 24, 2014
In concerts, at house parties, even in the hallway of apartment buildings, you may have come into contact and been exposed to secondhand marijuana smoke.
In situations like these, people often worry how breathing someone else’s marijuana smoke affects them. A couple of common questions and the answers may help you see through the fog of this smoky situation.
Can you get high from inhaling secondhand marijuana smoke?
You may have heard the phrase “contact high,” about someone breathing secondhand marijuana smoke and feeling a buzz. There have been studies that show in extreme conditions, with lots of smoke blown directly into your face, you can feel the high and it can even show up in a urine test. But this is not a normal circumstance.
Studies show that very little THC is exhaled back into the air when a smoker exhales. So little, in fact, that if you sat in a room while people exhaled the smoke of four marijuana cigarettes (sometimes called joints) in one hour, you wouldn’t get high. You would have to be trapped in a room breathing the smoke of 16 burning joints before it you started to show signs of being high.
Can you fail a drug test from inhaling secondhand marijuana smoke?
Again, probably not.
Since the amount of THC exhaled by marijuana smokers is so low, it would take a lot of secondhand exposure to fail a drug test.
In a 2010 study, researchers measured the effect of secondhand marijuana smoke on non-marijuana smokers. The non-smokers were placed in a well-ventilated space with people casually smoking marijuana for 3 hours. The researchers then took blood and urine samples from the nonsmokers. They found that THC was present, but the amount was well below the level to needed to fail a drug test. Another study found similar results: Testing positive is rare and limited to the hours directly following exposure.
What are the health effects of inhaling secondhand marijuana smoke?
Researchers are still working to figure this out. We still don’t know how a person is affected if they live with a regular marijuana smoker. We also don’t know how higher amounts of THC in today’s marijuana cigarettes affects secondhand smoke.
A recent study on rats suggests that secondhand marijuana smoke can do as much damage to your heart and blood vessels as secondhand tobacco smoke. But that study has not yet been done on humans.
We also know marijuana smoke contains harmful and cancer-causing chemicals, the same way tobacco smoke does. But we still don’t know how it affects a person’s health in the long run. Lots more research still needs to be done.
Tell us in comments, what would you do if someone was smoking marijuana near you?
Some chemicals in the marijuana plant might be useful in the world of medicine—like preventing nausea and blocking pain, and possibly treating other problems and diseases. The trick is for scientists to get these results without the harmful effects.
Researchers are studying these chemicals—so that they can develop medications that are chemically similar to THC but don't negatively affect the brain.
Mind Over Matter is produced by the National Institute on Drug Abuse, National Institutes of Health. Feel free to reprint this publication. Citation of the source is appreciated. NIH Publication No. 14-3859. Printed 1997. Reprinted 1998, 2000, 2003, 2005, 2006. Revised 2007, 2014.
The principles listed below are the result of long-term research studies on the origins of drug abuse behaviors and the common elements of effective prevention programs. These principles were developed to help prevention practitioners use the results of prevention research to address drug use among children, adolescents, and young adults in communities across the country. Parents, educators, and community leaders can use these principles to help guide their thinking, planning, selection, and delivery of drug abuse prevention programs at the community level.
Prevention programs are generally designed for use in a particular setting, such as at home, at school, or within the community, but can be adapted for use in several settings. In addition, programs are also designed with the intended audience in mind: for everyone in the population, for those at greater risk, and for those already involved with drugs or other problem behaviors. Some programs can be geared for more than one audience.
NIDA's prevention research program focuses on risks for drug abuse and other problem behaviors that occur throughout a child's development, from pregnancy through young adulthood. Research funded by NIDA and other Federal research organizations—such as the National Institute of Mental Health and the Centers for Disease Control and Prevention—shows that early intervention can prevent many adolescent risk behaviors.
Principle 1 - Prevention programs should enhance protective factors and reverse or reduce risk factors (Hawkins et al. 2002).
- The risk of becoming a drug abuser involves the relationship among the number and type of risk factors (e.g., deviant attitudes and behaviors) and protective factors (e.g., parental support) (Wills et al. 1996).
- The potential impact of specific risk and protective factors changes with age. For example, risk factors within the family have greater impact on a younger child, while association with drug-abusing peers may be a more significant risk factor for an adolescent (Gerstein and Green 1993; Dishion et al. 1999).
- Early intervention with risk factors (e.g., aggressive behavior and poor self-control) often has a greater impact than later intervention by changing a child's life path (trajectory) away from problems and toward positive behaviors (Ialongo et al. 2001; Hawkins et al. 2008).
- While risk and protective factors can affect people of all groups, these factors can have a different effect depending on a person's age, gender, ethnicity, culture, and environment (Beauvais et al. 1996; Moon et al. 1999).
Principle 2 - Prevention programs should address all forms of drug abuse, alone or in combination, including the underage use of legal drugs (e.g., tobacco or alcohol); the use of illegal drugs (e.g., marijuana or heroin); and the inappropriate use of legally obtained substances (e.g., inhalants), prescription medications, or over-the-counter drugs (Johnston et al. 2002).
Principle 3 - Prevention programs should address the type of drug abuse problem in the local community, target modifiable risk factors, and strengthen identified protective factors (Hawkins et al. 2002).
Principle 4 - Prevention programs should be tailored to address risks specific to population or audience characteristics, such as age, gender, and ethnicity, to improve program effectiveness (Oetting et al. 1997; Olds et al. 1998; Fisher et al. 2007; Brody et al. 2008).
Principle 5 - Family-based prevention programs should enhance family bonding and relationships and include parenting skills; practice in developing, discussing, and enforcing family policies on substance abuse; and training in drug education and information (Ashery et al. 1998).
Family bonding is the bedrock of the relationship between parents and children. Bonding can be strengthened through skills training on parent supportiveness of children, parent-child communication, and parental involvement (Kosterman et al. 1997; Spoth et al. 2004).
Parental monitoring and supervision are critical for drug abuse prevention. These skills can be enhanced with training on rule-setting; techniques for monitoring activities; praise for appropriate behavior; and moderate, consistent discipline that enforces defined family rules (Kosterman et al. 2001).
Drug education and information for parents or caregivers reinforces what children are learning about the harmful effects of drugs and opens opportunities for family discussions about the abuse of legal and illegal substances (Bauman et al. 2001).
Brief, family-focused interventions for the general population can positively change specific parenting behavior that can reduce later risks of drug abuse (Spoth et al. 2002b).
Principle 6 - Prevention programs can be designed to intervene as early as infancy to address risk factors for drug abuse, such as aggressive behavior, poor social skills, and academic difficulties (Webster-Stratton 1998; Olds et al. 1998; Webster-Stratton et al. 2001; Fisher et al. 2007).
Principle 7 - Prevention programs for elementary school children should target improving academic and social-emotional learning to address risk factors for drug abuse, such as early aggression, academic failure, and school dropout. Education should focus on the following skills (Conduct Problems Prevention Research Group 2002; Ialongo et al. 2001; Riggs et al. 2006; Kellam et al. 2008; Beets et al. 2009):
- emotional awareness
- social problem-solving and
- academic support, especially in reading
Principle 8 - Prevention programs for middle or junior high and high school students should increase academic and social competence with the following skills (Botvin et al. 1995; Scheier et al. 1999; Eisen et al. 2003; Ellickson et al. 2003; Haggerty et al. 2007):
- study habits and academic support
- peer relationships
- self-efficacy and assertiveness
- drug resistance skills
- reinforcement of anti-drug attitudes and
- strengthening of personal commitments against drug abuse
Principle 9 - Prevention programs aimed at general populations at key transition points, such as the transition to middle school, can produce beneficial effects even among high-risk families and children. Such interventions do not single out risk populations and, therefore, reduce labeling and promote bonding to school and community (Botvin et al. 1995; Dishion et al. 2002; Institute of Medicine 2009).
Principle 10 - Community prevention programs that combine two or more effective programs, such as family-based and school-based programs, can be more effective than a single program alone (Battistich et al. 1997; Spoth et al. 2002c; Stormshak et al. 2005).
Principle 11 - Community prevention programs reaching populations in multiple settings—for example, schools, clubs, faith-based organizations, and the media—are most effective when they present consistent, community-wide messages in each setting (Chou et al. 1998; Hawkins et al. 2009).
Principle 12 - When communities adapt programs to match their needs, community norms, or differing cultural requirements, they should retain core elements of the original research-based intervention (Spoth et al. 2002b; Hawkins et al. 2009), which include:
- structure (how the program is organized and constructed)
- content (the information, skills, and strategies of the program) and
- delivery (how the program is adapted, implemented, and evaluated)
Principle 13 - Prevention programs should be long-term with repeated interventions (i.e., booster programs) to reinforce the original prevention goals. Research shows that the benefits from middle school prevention programs diminish without follow-up programs in high school (Botvin et al. 1995; Scheier et al. 1999).
Principle 14 - Prevention programs should include teacher training on good classroom management practices, such as rewarding appropriate student behavior. Such techniques help to foster students' positive behavior, achievement, academic motivation, and school bonding (Ialongo et al. 2001; Kellam et al. 2008).
Principle 15 - Prevention programs are most effective when they employ interactive techniques, such as peer discussion groups and parent role-playing, that allow for active involvement in learning about drug abuse and reinforcing skills (Botvin et al. 1995).
Principle 16 - Research-based prevention programs can be cost-effective. Similar to earlier research, recent research shows that for each dollar invested in prevention, a savings of up to $10 in treatment for alcohol or other substance abuse can be seen (Aos et al. 2001; Hawkins et al. 1999; Pentz 1998; Spoth et al. 2002a; Jones et al. 2008; Foster et al. 2007; Miller and Hendrie 2009).
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- Conduct Problems Prevention Research Group. Predictor variables associated with positive Fast Track outcomes at the end of third grade. J Abnorm Child Psychol 30(1):37-52, 2002.
- Dishion, T.; McCord, J.; and Poulin, F. When interventions harm: Peer groups and problem behavior. Am Psychol 54:755-764, 1999.
- Dishion, T.; Kavanagh, K.; Schneiger, A.K.J.; Nelson, S.; and Kaufman, N. Preventing early adolescent substance use: A family centered strategy for the public middle school. Prev Sci 3(3):191-202, 2002.
- Eisen, M.; Zellman, G.L.; and Murray, D.M. Evaluating the Lions-Quest "Skills for Adolescence" drug education program: Second-year behavior outcomes. Addict Behav 28(5):883-897, 2003.
- Ellickson, P.L.; McCaffrey, D.F.; Ghosh-Dastidar, B.; and Longshore, D. New inroads in preventing adolescent drug use: Results from a large-scale trial of project ALERT in middle schools. Am J Public Health 93(11):1830-1836, 2003.
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- Foster, E.M.; Olchowski, A.E.; and Webster-Stratton, C.H. Is stacking intervention components cost-effective? An analysis of the Incredible Years Program. J Am Acad Child Adolesc Psychiatry 46(11):1414-1424, 2007.
- Gerstein, D.R., and Green, L.W., eds. Preventing drug abuse: What do we know? Washington, DC: National Academy Press, 1993.
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- Kosterman, R.; Hawkins, J.D.; Haggerty, K.P.; Spoth, R.; and Redmond, C. Preparing for the drug free years: Session-specific effects of a universal parent-training intervention with rural families. J Drug Educ 31(1):47-68, 2001.
- Miller, T.R., and Hendrie, D. Substance abuse prevention dollars and cents: A cost-benefit analysis. Substance Abuse and Mental Health Services Administration, Center for Substance Abuse Prevention. Rockville, MD: DHHS Pub. No. (SMA) 07-4298, 2009.
- Moon, D.; Hecht, M.; Jackson, K.; and Spellers, R. Ethnic and gender differences and similarities in adolescent drug use and refusals of drug offers. Subst Use Misuse 34(8):1059-1083, 1999.
- Oetting, E.; Edwards, R.; Kelly, K.; and Beauvais, F. Risk and protective factors for drug use among rural American youth. In: Robertson, E.B.; Sloboda, Z.; Boyd, G.M.; Beatty, L.; and Kozel, N.J., eds. Rural Substance Abuse: State of Knowledge and Issues. NIDA Research Monograph No. 168. Washington, DC: U.S. Government Printing Office, pp. 90-130, 1997.
- Olds, D.; Henderson, C.R.; Cole, R.; Eckenrode, J.; Kitzman, H.; Luckey, D.; Pettit, L.; Sidora, K.; Morris, P. and Powers, J. Long-term effects of nurse home visitation on children's criminal and antisocial behavior: 15-year follow-up of a randomized controlled trial. JAMA 280(14):1238-1244, 1998.
- Pentz, M.A.; Costs, benefits, and cost-effectiveness of comprehensive drug abuse prevention. In: Bukoski, W.J., and Evans, R.I., eds. Cost-benefit/cost-effectiveness research of drug abuse prevention: Implications for programming and policy. NIDA Research Monograph No. 176. Washington, DC: U.S. Government Printing Office, pp. 111-129, 1998.
- Riggs, N.R.; Greenberg, M.T.; Kusche, C.A.; and Pentz, M.A. The mediational role of neurocognition in the behavioral outcomes of a social-emotional prevention program in elementary school students: Effects of the PATHS curriculum. Prev Sci 7(1):91-102, 2006.
- Scheier, L.; Botvin, G.; Diaz, T.; and Griffin, K. Social skills, competence, and drug refusal efficacy as predictors of adolescent alcohol use. J Drug Educ 29(3):251-278, 1999.
- Spoth, R.; Redmond, C.; Shin, C.; and Azevedo, K. Brief family intervention effects on adolescent substance initiation: School-level growth curve analyses 6 years following baseline. J Consult Clin Psychol 72(3):535-542, 2004.
- Spoth, R.; Guyull, M.; and Day, S. Universal family-focused interventions in alcohol-use disorder prevention: Cost effectiveness and cost benefit analyses of two interventions. J Stud Alcohol 63:219-228, 2002a.
- Spoth, R.L.; Redmond, C.; Trudeau, L.; and Shin, C. Longitudinal substance initiation outcomes for a universal preventive intervention combining family and school programs. Psychol Addict Behav 16(2):129-134, 2002b.
- Spoth, R.L.; Redmond, C.; Trudeau, L.; and C.S. Longitudinal substance initiation outcomes for a universal preventive intervention combining family and school programs. Psychol Addict Behav 16(2):129-134, 2002c.
- Stormshak, E.A.; Dishion, T.J.; Light, J.; and Yasui, M. Implementing family-centered interventions within the public middle school: linking service delivery to change in student problem behavior. J Abnorm Child Psychol 33(6):723-733, 2005.
- Webster-Stratton, C. Preventing conduct problems in Head Start children: Strengthening parenting competencies. J Consult Clin Psychol 66:715-730, 1998.
- Webster-Stratton, C.; Reid, J.; and Hammond, M. Preventing conduct problems, promoting social competence: A parent and teacher training partnership in Head Start. J Clin Child Psychol 30:282-302, 2001.
- Wills, T.; McNamara, G.; Vaccaro, D.; and Hirky, A. Escalated substance use: A longitudinal grouping analysis from early to middle adolescence. J Abnorm Psychol 105:166-180, 1996.
Information in this DrugFacts can also be found in Preventing Drug Use among Children and Adolescents, A Research-Based Guide for Parents, Educators, and Community Leaders, Second Edition, National Institute on Drug Abuse, 2003.Publication from NIDA:Yes
Also known as: “weed,” “pot,” “bud,” “grass,” “herb,” “Mary Jane,” “MJ,” “reefer,” “skunk,” “boom,” “gangster,” “kif,” “chronic,” and “ganja”
Marijuana is a mixture of the dried and shredded leaves, stems, seeds, and flowers of Cannabis sativa—the hemp plant. The mixture can be green, brown, or gray. Stronger forms of the drug include sinsemilla (sin-seh-me-yah), hashish (“hash” for short), and hash oil.
Of the approximately 400 chemicals in marijuana, delta-9-tetrahydrocannabinol, known as THC, is responsible for many of the drug’s psychotropic (mind-altering) effects. It’s this chemical that changes how the brain works, distorting how the mind perceives the world.
It is illegal to buy, sell, or carry marijuana under Federal law. The Federal Government considers marijuana a Schedule I substance—having no medicinal uses and high risk for abuse. However, across the United States, marijuana state laws for adult use are changing. As of 2014, 23 states and the District of Columbia have passed laws allowing the use of marijuana as a treatment for certain medical conditions.
In addition, four states and the District of Columbia have legalized marijuana for adult recreational use. Because of concerns over the possible harm to the developing teen brain and the risk of driving under the influence, marijuana use by people under age 21 is prohibited in all states.
Strength and Potency
The amount of THC in marijuana has increased over the past few decades—from an average of about 4 percent for marijuana and 7.5 percent for sinsemilla in the early 1990’s to almost 10 percent for marijuana and 16 percent for sinsemilla in 2013.1 Scientists don’t yet know what this increase in potency means for a person’s health. It could be that users take in higher amounts of THC, or they may adjust how they consume marijuana (like smoke or eat less) to compensate for the greater potency.
The honey-like resin from the marijuana plant has 3 to 5 times more THC than the plant itself. Smoking it (also called “dabbing”) can potentially lead to dangerous levels of intoxication requiring emergency treatment. People have been burned in fires and explosions caused by attempts to extract hash oil using butane (lighter fluid).
Marijuana is commonly smoked using pipes, water pipes called “bongs,” or hand-rolled cigarettes called “joints” or “nails.” It is sometimes also combined with tobacco in partially hollowed-out cigars, known as “blunts.” Recently vaporizers, that use heat without burning to produce a vapor, have increased in popularity. Marijuana can also be brewed as tea or mixed with food, sometimes called edibles.
In addition, concentrated resins containing high doses of marijuana’s active ingredients, including honey-like “hash oil,” waxy “budder,” and hard amber-like “shatter,” are increasingly popular among both recreational and medical users.
The main chemical in marijuana that affects the brain is delta-9-tetrahydrocannabinol (THC). When marijuana is smoked, THC quickly passes from the lungs into the bloodstream, which carries it to organs throughout the body, including the brain. As it enters the brain, THC attaches to cells, or neurons, with specific kinds of receptors called cannabinoid receptors. Normally, these receptors are activated by chemicals that occur naturally in the body. They are part of a communication network in the brain called the endocannabinoid system. This system is important in normal brain development and function.
Most of the cannabinoid receptors are found in parts of the brain that influence pleasure, memory, thinking, concentration, sensory and time perception, and coordinated movement. Marijuana triggers an increase in the activity of the endocannabinoid system, which causes the release of dopamine in the brain's reward centers, creating the pleasurable feelings or “high.” Other effects include changes in perceptions and mood, lack of coordination, difficulty with thinking and problem solving, and disrupted learning and memory.
Certain parts of the brain have a lot of cannabinoid receptors. These areas are the hippocampus, the cerebellum, the basal ganglia, and the cerebral cortex. (Learn more about these areas and how THC affects them.) The functions that these brain areas control are the ones most affected by marijuana:
- Learning and memory. The hippocampus 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. A recent study followed people from age 13 to 38 and found that those who used marijuana a lot in their teens had up to an 8 point drop in IQ, even if they quit in adulthood.3,4
- Coordination. THC affects the cerebellum, the area of our brain that controls balance and coordination, and the basal ganglia, another part of the brain that helps control movement. These effects can influence performance in such activities as sports, driving, and video games.
- Judgment. Since THC affects areas of the frontal cortex involved in decision making, using it can cause you to do things you might not do when you are not under the influence of drugs—such as engaging in risky sexual behavior, which can lead to sexually transmitted diseases (STDs) like HIV, the virus that causes AIDS—or getting in a car with someone who’s been drinking or is high on marijuana.
When marijuana is smoked, its effects begin almost immediately and can last from 1 to 3 hours. Decision making, concentration, and memory can suffer for days after use, especially in regular users.2
If marijuana is consumed in foods or beverages, the effects of THC appear later—usually in 30 minutes to 1 hour—but can last over 4 hours.
Learn more about how the brain works and what happens when a person uses drugs.
The changes that take place in the brain when a person uses marijuana can cause serious health problems and affect a person’s daily life.
Effects on Health
Within a few minutes after inhaling marijuana smoke, a person’s heart rate speeds up, the bronchial passages (the pipes that let air in and out of your lungs) relax and become enlarged, and blood vessels in the eyes expand, making the eyes look red. While these and other effects seem harmless, they can take a toll on the body.
- Increased heart rate. When someone uses marijuana, 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. The increased heart rate forces the heart to work extra hard to keep up.
- Respiratory (lung and breathing) problems. Smoke from marijuana irritates the lungs, causing breathing and lung problems among regular users similar to those experienced by people who smoke tobacco—like a daily cough and a greater risk for lung infections such as pneumonia. While research has not found a strong association between marijuana and lung cancer, many people who smoke marijuana also smoke cigarettes, which do cause cancer. And, some studies have suggested that smoking marijuana could make it harder to quit cigarette smoking.5
- Increased risk for mental health problems. Marijuana use has been linked with depression and anxiety, as well as suicidal thoughts among adolescents. In addition, research has suggested that in people with a genetic risk for developing schizophrenia, smoking marijuana during adolescence may increase the risk for developing psychosis and developing it at an earlier age. Researchers are still learning exactly what the relationship is between these mental health problems and marijuana use.
- Increased risk of problems for an unborn baby. Pregnant women who use marijuana may risk changing the developing brain of the unborn baby. These changes could contribute to problems with attention, memory, and problem solving.
Effects on School and Social Life
The effects of marijuana on the brain and body can have a serious impact on a person’s life.
- Reduced school performance. Students who smoke marijuana tend to get lower grades and are more likely to drop out of high school than their peers who do not use. The effects of marijuana on attention, memory, and learning can last for days or weeks. These effects have a negative impact on learning and motivation. In fact, people who use marijuana regularly for a long time are less satisfied with their lives and have more problems with friends and family compared to people who do not use marijuana.
- Impaired driving. It is unsafe to drive while under the influence of marijuana. Marijuana affects a number of skills required for safe driving—alertness, concentration, coordination, and reaction time—so it’s not safe to drive high or to ride with someone who’s been smoking. Marijuana makes it hard to judge distances and react to signals and sounds on the road. Marijuana is the most common illegal drug involved in auto fatalities. High school seniors who smoke marijuana are 2 times more likely to receive a traffic ticket and 65% more likely to get into an accident than those who don’t smoke.6 In 2011, among 12th graders, 12.5% reported that within the past 2 weeks they had driven after using marijuana.7 And combining marijuana with drinking even a small amount of alcohol greatly increases driving danger, more than either drug alone. Learn more about what happens when you mix marijuana and driving.
- Potential gateway to other drugs. Most young people who use marijuana do not go on to use other drugs. However, those who use marijuana, alcohol, or tobacco during their teen years are more likely to use other illegal drugs. It isn’t clear why some people do go on to try other drugs, but researchers have a few theories. The human brain continues to develop into the early 20s. Exposure to addictive substances, including marijuana, may cause changes to the developing brain that make other drugs more appealing. Animal research supports this possibility—for example, early exposure to marijuana makes opioid drugs (like Vicodin or heroin) more pleasurable. In addition, someone who uses marijuana is more likely to be in contact with people who use and sell other drugs, increasing the risk for being encouraged or tempted to try them. Finally, people at high risk for using drugs may use marijuana first because it is easy to get (like cigarettes and alcohol).
For more information on the effects of marijuana, see our Marijuana Research Report.
6. U.S. Department of Transportation. National Highway Traffic Safety Administration. Traffic Safety Facts. Drug Involvement of Fatally Injured Drivers. Washington, DC, November 2010. Available at: http://www-nrd.nhtsa.dot.gov/Pubs/811415.pdf.
Yes, marijuana is addictive. A user may feel the urge to smoke marijuana again and again to re-create the “high.” Repeated use could lead to addiction—which means the person has trouble controlling their drug use and often cannot stop even though they want to.
It is estimated that about 1 in 6 people who start using as a teen, and 25% to 50% percent of those who use it every day, become addicted to marijuana. What causes one person to become addicted to marijuana and another not to depends on many factors—including their family history (genetics), the age they start using, whether they also use other drugs, their family and friend relationships, and whether they take part in positive activities like school or sports (environment).
People who use marijuana may also feel withdrawal when they stop using the drug. Withdrawal symptoms may include:
- Lack of appetite, which can lead to weight loss
- Drug cravings
These effects can last for several days to a few weeks after drug use is stopped. Relapse (returning to the drug after you’ve quit) is common during this period because people also crave the drug to relieve these symptoms.
It is very unlikely for a person to overdose and die from marijuana use. However, people can and do injure themselves and die because of marijuana's effects on judgment, perception, and coordination, for example, when driving under the influence of the drug. Also, people can experience extreme anxiety (panic attacks) or psychotic reactions (where they lose touch with reality and may become paranoid).
Marijuana is the most common illicit drug used in the United States by teens as well as adults. The growing belief by young people that marijuana is a safe drug may be the result of recent public discussions about medical marijuana and the public debate over the drug’s legal status. In addition, some teens believe marijuana cannot be harmful because it is “natural.” But not all natural plants are good for you—take tobacco, for example.
See the most recent statistics on teen drug use from NIDA’s Monitoring the Future study below:
Swipe left or right to scroll.
Monitoring the Future Study: Trends in Prevalence of Marijuana/ Hashish for 8th Graders, 10th Graders, and 12th Graders; 2014 (in percent)* Drug Time Period 8th Graders 10th Graders 12th Graders Marijuana/ Hashish Lifetime 15.60 33.70 44.40 Past Year 11.70 [27.30] 35.10 Past Month 6.50 16.60 21.20 Daily 1.00 [3.40] 5.80
For more statistics on teen drug use, see NIDA’s Monitoring the Future study.
There is no difference between marijuana dispensed to treat a medical condition and marijuana bought on the street for recreational use. The difference is just in how it is used.
The marijuana plant contains chemicals that may be useful for treating a range of illnesses or symptoms. A growing number of states (23 as of August 2014) have legalized the plant’s use for certain medical conditions. Although it is not legal or considered medicine by the Federal Government a few medications made from active chemicals in the plant called cannabinoids have been approved by the U.S. Food and Drug Administration (FDA). One of these cannabinoids, THC, has some medicinal properties in addition to its mind-altering effects. Pill versions of THC have been approved to treat nausea (feeling sick) in cancer patients and to increase appetite in some patients with AIDS.
Another cannabinoid chemical called cannabidiol, which doesn’t have mind-altering effects, is also being studied for its possible uses as medicine. A new medication with a combination of THC and cannabidiol is available in several countries outside the United States as a mouth spray for treating symptoms of multiple sclerosis. There is some early evidence that cannabidiol may be useful in treating seizures in children with severe epilepsy, so a cannabidiol-based drug for that is also now being studied.
It is important to remember that because marijuana is often smoked, it can hurt lung health; these health risks as well as the way it impairs mental functioning may outweigh its value as a medical treatment, especially for people that are not very sick with cancer or other life-threatening diseases. Another problem with smoking or eating marijuana plant material is the ingredients vary a lot from plant to plant, so there is no way to get a precise dose every time or even know what dose you are getting. This is why scientists are busy studying safe ways that THC, cannabidiol, and other chemicals can be extracted from the marijuana plant to create safe medicines.
For more information, see Drug Facts—Is Marijuana Medicine?
If you or a friend are in crisis and need to speak with someone now, please call:
- National Suicide Prevention Lifeline at 1-800-273-TALK (they don't just talk about suicide—they cover a lot of issues and will help put you in touch with someone close by).
If you need information on treatment and where you can find it, you can call:
- Substance Abuse Treatment Facility Locator at 1-800-662-HELP or visit www.findtreatment.samhsa.gov.
For more information on how to help a friend or loved one, visit our Have a Drug Problem, Need Help? page.
- Commonly Abused Drugs Chart
- DrugFacts: Marijuana
- Marijuana: Facts for Teens
- Marijuana: Facts Parents Need to Know
- Mind Over Matter Teaching Guide and Series: Marijuana
- NIDA Notes Articles: Marijuana
- Research Report Series: Marijuana
Statistics and Trends
Monitoring the Future (University of Michigan):
Substance Abuse and Mental Health Services Administration: