Cannabis is the most popular illicit(ish) drug in the world, and it’s gaining in popularity as it becomes legal—medicinally or recreationally—in more and more states. But what actually happens in your body when you partake? Let’s take a look at this fascinating drug, its health effects, and potential concerns about using it.
- Cannabis is a controlled substance…lacking in controlled, scientific research
- What cannabis does to our brains in the first couple of hours
- Cannabis may have a long-term effect on memory and concentration
- Compared to other drugs, cannabis is less addictive and harmful
- Cannabis is more dangerous for teens
- Smoking is riskier than other methods of using
- There are many possible medical uses for cannabis
- The effects of marijuana on your memory
- Your Brain On: Marijuana
- The Effects of Marijuana on Your Body
- Respiratory system
- Circulatory system
- Central nervous system
- Digestive system
- Immune system
- What marijuana really does to your body and brain
- Marijuana and psychosis
- Pot and IQ
- Brain size, connectivity
- The brain’s reward system
- Noisy neurons
- Munchies and the brain
- Marijuana and the teenage brain
- Dangers of Marijuana: Long-Term Effects of Pot on the Brain and Body
- Endocannabinoids and What They Do
- Marijuana and Memory Problems
- From Youth to Adulthood
- Conditions of the Heart
- Marijuana Use by Pregnant or Nursing Mothers
- The Risk of Addiction and Testicular Cancer
- Health Risks and Research Restrictions
- The Cannabis Consensus
- 6 Shocking Ways Weed Can Affect Your Brain
- What is marijuana?
- How do people use marijuana?
- How does marijuana affect the brain?
- What are the other health effects of marijuana?
- Are there effects of inhaling secondhand marijuana smoke?
- Is marijuana a gateway drug?
- Can a person overdose on marijuana?
- Is marijuana addictive?
- What treatments are available for marijuana use disorder?
- Learn More
- This is Your Brain on Weed
- What Does a Person’s Brain Look Like When Deciding to Smoke Weed?
- What Does a Person’s Brain Look Like When They’re High?
- Now, let’s see what happens after long-term pot use…
- What Does a Person’s Brain Look Like After They’ve Smoked Weed for a Long Time?
- What Happens Inside Your Brain When You Smoke Weed?
Cannabis is a controlled substance…lacking in controlled, scientific research
Before we start, we should note that a whole lot more research needs to be done in this area. Although cannabis has been used for centuries as a medicine and as an inebriant (it’s even mentioned in the Old Testament several times as “kaneh-bosem”), we don’t know a great deal about the health effects of using it. That’s because there haven’t been many controlled studies on it, due to the way cannabis is classified by the federal government.
The Food and Drug Administration classifies cannabis as a Schedule I drug, with “no currently accepted medical use and a high potential for abuse.” (Fun fact: heroin, ecstasy, and LSD are also Schedule I drugs, but cocaine and meth are considered less dangerous Schedule II drugs.) There are two exceptions: FDA-approved drugs made from cannabidiol (CBD) with “no more than 0.1 percent tetrahydrocannabinols” are on schedule V, the same list as codeine-containing cough syrups. And hemp—defined as cannabis plants that contain less than 0.3% THC—is unscheduled thanks to the 2018 Farm Bill.
Because garden-variety cannabis is still on Schedule I, you need a license from the DEA and your study approved by the FDA. To obtain research-grade cannabis, you have to go through the National Institute on Drug Abuse, Popular Science explains. Otherwise, since it’s federally illegal to have cannabis (even in states that have legalized it), researchers working in hospitals, colleges, or other institutions that receive federal funding risk losing their funds to do this research.
There have long been movements to reclassify cannabis and open up the doors for more studies, but, for now, here’s what we do know about cannabis and our health.
What cannabis does to our brains in the first couple of hours
Cannabis contains at least 60 types of cannabinoids, chemical compounds that act on receptors throughout our brain. THC, or Tetrahydrocannabinol, is the chemical responsible for most of cannabis’s effects, including the euphoric high. THC resembles another cannabinoid naturally produced in our brains, anandamide, which regulates our mood, sleep, memory, and appetite.
Essentially, cannabinoids’ effect on our brains is to keep our neurons firing, magnifying our thoughts and perception and keeping us fixed on them (until another thought takes us on a different tangent). That’s why when you’re high, it’s really not a good time to drive, study for a test, or play sports that require coordination, like tennis or baseball. Like alcohol, caffeine, and sugar, cannabinoids also affect the levels of dopamine in our brain, often resulting in a sense of relaxation and euphoria.
Salon explains a few more ways cannabis interacts with our brains, such as impairing our ability to form new memories, and how cannabinoids cause the classic “munchies.”
The effects will depend on the amount taken, as well as how potent the preparation is (common cannabis contains 2 to 5% THC, while ganja can contain up to 15% THC and hashish oil between 15 and 60% THC). At high doses—and if you don’t follow our advice on edible safety—cannabis can produce scary curled-up-on-the-couch-for-hours hallucinatory states.
As with other drugs, cannabis’s effects will also vary by individual. Not all people may find it an enjoyable or relaxing experience; for those who have anxiety or are prone to panic attacks, cannabis could exacerbate their symptoms rather than bring on a sense of calm.
Cannabis may have a long-term effect on memory and concentration
The short-term effects of cannabis are generally felt within a few minutes, peak within 30 minutes, and wear off after about two or three hours. The bigger question is: what happens if we use marijuana more regularly, or are occasional but heavy users? Are there permanent cognitive and other health changes? Do we all turn into The Dude from the Big Lebowski?
Again, we don’t have many rigorous scientific studies on this, much less many longitudinal studies. A 2012 review of available research published in the Journal of Addiction Medicine, found that the immediate impairments on memory and concentration aren’t likely permanent. But a 2018 review by Colorado’s public health department concluded that daily users of cannabis can have impaired memory lasting more than a week after quitting. Whether memory or other cognitive problems may last longer than that is still unclear.
Colorado also has a list of statements about the health effects of using cannabis, and a detailed list of how strong the evidence is for each statement. Evidence for most of the mental health effects is “limited” or “mixed,” but a few findings have substantial evidence behind them. They include:
- Adolescents and young adults who use cannabis are more likely to develop psychotic symptoms and disorders like schizophrenia
- Heavy use of smoked cannabis is associated with chronic lung problems like bronchitis
- People who use cannabis can become addicted to it over time
Compared to other drugs, cannabis is less addictive and harmful
Addiction is a very complex topic. It’s possible for people to get addicted to anything that gives us pleasure. While cannabis addiction is real, it is a rarer addiction than other (legal or illegal) substances. Statistics say that 9 percent of people (roughly one out of 10) who use cannabis become dependent on it, compared to 32 percent of tobacco users, 20 percent of cocaine users, and 15 percent of alcohol drinkers.
When it comes to cannabis and other substances, some say what matters most might not be how addictive the substance is but how harmful it might be. Former Surgeon General Jocelyn Elders told CNN she supports legalizing cannabis, saying it “is not addictive, not physically addictive anyway.” Time reports:
As Dr. Elders also said on CNN, marijuana is nontoxic. You can fatally overdose on alcohol, heroin or cocaine, but the only way a dose of marijuana will kill you is if someone crushes you under a bale of it.
Although evidence shows that it’s possible to develop a substance use disorder, and withdrawal symptoms after stopping heavy use, cannabis has still been shown to be much less dangerous and addictive than other substances—over 100 times safer than alcohol—but that’s not to say it is completely harmless. How cannabis is consumed and prepared can make a big difference on its health effects, for better or worse, as well.
Cannabis is more dangerous for teens
The chances of getting addicted to cannabis increase if you’re a daily user or if you start when you’re a teen. According to the National Institute on Drug Abuse, cannabis addiction goes up to about 17 percent in those who start using young (in their teens) and to 25 to 50 percent among daily users.
Dr. Damon Raskin, internist and Diplomat of the American Board of Addiction Medicine, advises:
Marijuana these days can cause changes in the brain that impair learning, especially in teenagers as their brains have not finished developing. Brains are not fully developed until the age of 25 or 26. Chronic marijuana use can lead to changes in both personality, judgment, and reasoning skills.
Pot damages the heart and lungs, increases the incidence of anxiety, depression and schizophrenia, and it can trigger acute psychotic episodes. Many adults appear to be able to use marijuana with relatively little harm, but the same cannot be said of adolescents, who are about twice as likely as adults to become addicted to marijuana.
Much of the marijuana available today is more potent than it was in the past, so the potential exists for it to have more intense deleterious effects on the user. Medical professionals are seeing more emergency room visits with excessive vomiting, and with adolescents, there is greater risk of psychosis and delirium.
If you’re a parent, this is another reminder to talk to your kids about drugs, especially during those formative years.
Smoking is riskier than other methods of using
Cannabis is most commonly smoked, but it can be used in vaporizers, turned into a tea, or used as an ingredient in foods as an edible. Oils and tinctures are often made from the cannabis plant as well for medicinal purposes. Of the many ways to use cannabis, smoking seems to have the most harmful side effects. According to the American Lung Association:
Smoke is harmful to lung health. Whether from burning wood, tobacco or marijuana, toxins and carcinogens are released from the combustion of materials. Smoke from marijuana combustion has been shown to contain many of the same toxins, irritants and carcinogens as tobacco smoke.
Beyond just what’s in the smoke alone, marijuana is typically smoked differently than tobacco. Marijuana smokers tend to inhale more deeply and hold their breath longer than cigarette smokers, which leads to a greater exposure per breath to tar.
Secondhand marijuana smoke contains many of the same toxins and carcinogens found in directly inhaled marijuana smoke, in similar amounts if not more.
A review of studies in 2013, however, found mixed evidence linking heavy, long-term cannabis use to pulmonary disease or lung cancer and concluded that there’s definitely a bigger risk for these if you smoke tobacco.
Still, regular users might consider other options besides smoking, such as vaping and edibles. Ata Gonzalez, CEO of G FarmaLabs, says:
Traditional methods (joints, blunts, etc), first off, aren’t the most efficient and certainly aren’t the cleanest ways to do it. These paper-based methods can be harsh on throat and lung tissue over time, potentially introduce the possibility of inhaling mold spores, and can be carcinogenic depending on what the cannabis is rolled in. Vaporizers are a much better option if you’re going to smoke it, not only because it’s much more discreet, but it introduces cannabinoids into the bloodstream as a gas through heat, rather than as smoke due to combustion. Vaping also reduces any possible exposure to harmful toxins/byproducts because the marijuana is never burned.
Conversely, there’s always the edibles option. This method is the most efficient way to get cannabinoids into the system because it’s done through the gastrointestinal tracts instead of the lungs – this also means that absorption is slower and the effects seem like they’re delayed, but that’s because the body has to process THC through the liver. The resulting effect, however, is a much more body-focused “high” that’s optimal for pain relief. Tinctures and tonics are sometimes classified in this subset/consumption category. Finally, we have topical solutions made with cannabis oil (e.g. salves, lotions, ointments, etc.) which are best used as anti-inflammatories and analgesics.
Additionally, if you partake, you’ll want to know where your cannabis came from—who grew it, how they grew it, how they harvested it, and so on. (Soon you’ll be able to buy Willie Nelson’s own brand of weed from his stores!) If you don’t know, however, consider Global Healing Center editor Ben Nettleton’s suggestion to water cure your stuff:
Water curing is basically just soaking your stuff in water and changing the water several times. The water draws out any water soluble impurities. So any leftover fertilizer, pesticides, fungus (recent Smithsonian touched on the prevalence of that), and even innocuous unnecessary compounds like salts and chlorophyll. Pretty much just like giving it a wash. THC is not water soluble so you don’t lose any of what you want.
We tend to think of cannabis as a hippy all-natural movement, but today legal cannabis is the fastest growing industry in the US—a multi-billion dollar industry—and the purity and quality of the cannabis can matter a great deal to your health and its effect on you.
There are many possible medical uses for cannabis
Finally, there are the potential medical uses of cannabis for a wide variety of conditions. 23 US states and DC have legalized the medical use of cannabis to treat symptoms of cancer, AIDS, arthritis, multiple sclerosis, migraines, epilepsy, nausea, and other conditions. 76% of doctors surveyed said they would prescribe cannabis for medicinal purposes. And Procon.org’s analysis of 60 peer-reviewed studies on medical marijuana found 68% of them concluded treatments were positive for the conditions treated.
As with the adverse effects of cannabis, however, the research here is still limited and lacking. CNN’s Dr. Sanjay Gupta, who changed his stance on cannabis to now question cannabis’s categorization as a Schedule I drug, says that of the recent papers on it, the overwhelming majority—about 94%—are designed to investigate the harm while only 6% investigate the benefits of medical cannabis.
So what we’re left with is anecdotal evidence. Greta Carter, cannabis activist, entrepreneur, and founder of a chain of clinics tells Lifehacker:
What we know is that the VA has clearly identified the benefits of marijuana on post-traumatic stress syndrome. We also know that parents who have struggled daily with children suffering from seizures and movement disorders go to extremes to relocate their families to states that will allow them access to the medicine. We’ve heard from patients with AIDS and Cancer who find benefits from cannabis. There are studies outside of the US that actually show tumors being reduced with cannabis treatment. I find it unconscionable that we as a country that have over 500 deaths a year to aspirin, and none to cannabis in its entire history would ever try to stand in the way of this plant being readily available to whomever might seek it.
With those being the extreme situations advocating for cannabis, I am more of the position that cannabis is a part of overall wellness for many. … Having served over 1,000 patients a month (40K to date) walking through my clinics and the average age growing older each year, the stories I’m more accustomed to hearing go like this: The aging population who come in and report that they take over 14 kinds of medications (and some of them are meds to offset the side effects of the other meds), in a year after incorporating cannabis, they come back and are down to 2 or 3 meds and enjoying a better quality of life. From those who have suffered from addiction to pain pills, they use cannabis to manage their pain and are off of their pain meds. The stories going on and on.
Opponents of medical cannabis argue that it’s too dangerous to use (though the arguments seem to be mostly associated with the effects of smoking rather than cannabis in general or administered in other ways), that cannabis is addictive, and that legal drugs make cannabis unnecessary.
Health professionals and researchers (and lawmakers) on both sides of the debate continue to argue the pros and cons of cannabis use. As for us regular people, more than half of polled Americans said they were in favor of cannabis (recreational or medical) being sold legally, just like alcohol is.
As ever, “further research is recommended” (isn’t that how all studies conclude?) In the case of cannabis, though, we really do need more.
This story was originally published in March 2015 and was updated on August 29, 2019 with current information.
Photos by Nemo, Geralt, 887OS (), trawin, Caveman Chuck Coker, GoToVan, wackystuff.
The effects of marijuana on your memory
As you get older, certain aspects of memory normally decline, but that does not mean you are powerless to protect your brain as you age. In fact, there is a lot you can do. In addition to getting regular exercise and eating a Mediterranean style diet, you can also consider what is known and not known about marijuana.
Cannabis contains varying amounts of the potentially therapeutic compound cannabidiol (CBD), which may help quell anxiety. However, there’s no question that marijuana (the dried flowers and leaves of the cannabis plant) can produce short-term problems with thinking, working memory, executive function, and psychomotor function (physical actions that require conscious thought, such as driving a car or playing a musical instrument). This is because marijuana’s main psychoactive chemical, THC, causes its effect by attaching to receptors in brain regions that are vital for memory formation, including the hippocampus, amygdala, and cerebral cortex. The extent to which long-term use of marijuana (either for medical or recreational purposes) produces persistent cognitive problems is not known.
The laws regarding marijuana differ from state to state. Some outlaw it altogether, while others allow it for medical purposes—to help relieve pain and nausea, for example. And in a growing number of states, marijuana is legal for recreational use. But it remains illegal at the federal level. For that reason, it has been difficult for researchers in the United States to obtain federal research funding to study marijuana, limiting the amount of high-quality evidence available.
What you can do: If you use marijuana, understand you may have problems with memory and related cognitive functions while under the influence. There also is the possibility of developing cognitive problems with long-term use.
For more information on memory and cognitive function, read Improving Memory, a Special Health Report from Harvard Medical School.
Image: tvirbickis/Getty Images
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
Your Brain On: Marijuana
When it comes to drugs, marijuana is easily one of the most controversial. And today-4/20, a date when weed enthusiasts across America celebrate their favorite recreational (and in many places, still illicit) substance-pot is getting even more ink.
No matter your opinion of this hot topic drug (and its legalization in some states), it’s hard to take part in the conversation until you understand it-and the ways that lighting up can impact your brain. The problem is, a lot of those ways still remain a mystery-even to scientists who’ve spent years researching the drug. What we do know is that today, marijuana can be consumed in foods, drinks, through pill form, a vaporizer, and through smoking.
The hundreds of chemical compounds-many of which are called cannabinoids-impact everyone (and every part of your body and brain) differently. Some cannabinoids have been touted for their medicinal benefits: shown to ease the nausea associated with chemotherapy or lessen the pressures of disease like glaucoma. Other have been linked to anxiety, and the “high” you feel when lighting up with friends.
Below, a recap of just one small part of the pot puzzle: the chemical changes that tend to occur in the brain if you light up recreationally.
When you inhale pot smoke, you’re sucking a bunch of plant compounds into your lungs, including weed’s famous ingredient: the psychoactive delta-9-tetrahydrocannabinol (THC)-the one that makes you high. According to resources from the National Institutes of Health, THC passes from your lungs into your bloodstream, where it’s carried on to your brain. There, it binds to cells called cannabinoid receptors, which would normally interact with chemicals that exist naturally in your body.
Almost immediately, these receptors trigger a number of responses from your autonomic nervous system, including vasodilation, or the expansion of your blood vessels, explains Ruben Baler, Ph.D., a health scientist with the National Institute on Drug Abuse (NIDA). This irritates your eyes, which is why they may turn red or itchy, and speeds your heart rate by 20 percent or more, shows research from the Kaiser Permanente Medical Care Program. Like most other drugs, THC spurs the release of feel-good chemical dopamine.
Those cannabinoid receptors the THC latched onto are part of your noodle’s endocannabinoid system, which helps control memory, mood, concentration, time perception, and motor skills. And THC over-activates and discombobulates it. Put more simply, THC disrupts the way your brain communicates within itself, explains Matthew J. Smith, Ph.D., who researches pot at Northwestern University. That communication disruption leads to the different physical, emotional, and psychological experiences-good or bad-associated with being stoned. Because everyone’s brain is different, the changes caused by THC affect everyone a little differently, research suggests.
Your brain is like a computer that processes information in a precise, consistent flow. THC and the other chemicals in weed scramble this flow, Baler explains. The more you smoke, the more that flow is scrambled.
Your endocannabinoid system also plays a role in energy regulation and food intake, which may explain why some people get “the munchies” after smoking, Baler says. Because THC also messes with your brain’s pleasure receptors, food (or anything your senses experience) may seem more pleasurable. THC may also disrupt your brain’s mood and emotional pathways in unpleasant ways, triggering paranoia, panic, and other hallmarks of a bad trip, NIDA resources show.
RELATED: The Science Behind Why You Get the Munchies
00:02:15 to 00:06:00
As the drug wears off, so does the uptick in feel-good chemicals like dopamine. And that dopamine drop-off can lead to sadness or even depression, research shows. The pot-induced changes in receptor and hormone activity can also leave your brain a little burned out and slow, similar to a night of heavy drinking, NIDA reports explain.
00:24:00 and Beyond
The science gets more controversial when it comes to weed’s long-term effects. It appears, though, that chronic THC activation of those cannabinoid receptors in your brain may leave them unable to function properly, Smith explains. Among teenagers who smoked pot daily for several months or years, Smith and his colleagues at Northwestern discovered memory impairments even two years after the teens had given up weed.
There’s also evidence that, if marijuana use starts at a young age (when your brain is still developing), pot can permanently rewire your noodle, creating “faulty connections” among the areas that rely on seamless coordination to process and store information, Baler adds. (Studies have found the same types of issues among kids who drink alcohol.)
The long-term effects of pot smoking on adult brains are less clear. People who start smoking marijuana in adulthood don’t show significant IQ declines, a NIDA report states. But some recent research published by the Society of Nuclear Medicine shows that grownups who smoke every day suffer a 20 percent drop in the number of receptors that control brain functions ranging from emotion to appetite. But those receptors pop back to normal levels once people quit the drug, the study authors say.
- By Markham Heid
The Effects of Marijuana on Your Body
Marijuana is made from the shredded and dried parts of the cannabis plant, including the flowers, seeds, leaves, and stems. It’s also known as pot, weed, hash, and dozens of other names. While many people smoke or vape it, you can also consume marijuana as an ingredient in food, brewed tea, or oils.
Different methods of taking the drug may affect your body differently. When you inhale marijuana smoke into your lungs, the drug is quickly released into your bloodstream and makes its way to your brain and other organs. It takes a little longer to feel the effects if you eat or drink marijuana.
There is ongoing controversy around the effects of marijuana on the body. People report various physical and psychological effects, from harm and discomfort to pain relief and relaxation.
Here’s what happens to your body when this drug enters your bloodstream.
Marijuana can be used in some states for medical reasons, and in some areas, recreational use is legal as well. No matter how you use marijuana, the drug can cause immediate and long-term effects, such as changes in perception and increased heart rate. Over time, smoking marijuana may cause chronic cough and other health issues.
The effects of marijuana on the body are often immediate. Longer-term effects may depend on how you take it, how much you use, and how often you use it. The exact effects are hard to determine because marijuana has been illegal in the U.S., making studies difficult and expensive to conduct.
But in recent years, the medicinal properties of marijuana are gaining public acceptance. As of 2017, 29 states plus the District of Columbia have legalized medical marijuana to some extent. THC and another ingredient called cannabidiol (CBD) are the main substances of therapeutic interest. The National Institutes of Health funded research into the possible medicinal uses of THC and CBD, which is still ongoing.
With the potential for increased recreational use, knowing the effects that marijuana can have on your body is as important as ever. Read on to see how it affects each system in your body.
Much like tobacco smoke, marijuana smoke is made up of a variety of toxic chemicals, including ammonia and hydrogen cyanide, which can irritate your bronchial passages and lungs. If you’re a regular smoker, you’re more likely to wheeze, cough, and produce phlegm. You’re also at an increased risk of bronchitis and lung infections. Marijuana may aggravate existing respiratory illnesses, such as asthma and cystic fibrosis.
Marijuana smoke contains carcinogens, so it may increase your risk of lung cancer too. However, studies on the subject have had mixed results. According to the National Institute of Drug Abuse (NIDA), there is no conclusive evidence that marijuana smoke causes lung cancer. More research is needed.
THC moves from your lungs into your bloodstream and throughout your body. Within minutes, your heart rate may increase by 20 to 50 beats per minute. That rapid heartbeat can continue for up to three hours. If you have heart disease, this could raise your risk of heart attack.
One of the telltale signs of recent marijuana use is bloodshot eyes. The eyes look red because marijuana causes blood vessels in the eyes to expand.
THC can also lower pressure in the eyes, which can ease symptoms of glaucoma for a few hours. More research is needed to understand the active ingredients in marijuana and whether it’s a good treatment for glaucoma.
What’s the impact of cannabis on health? “
In the long term, marijuana has a possible positive effect on your circulatory system. Research isn’t conclusive yet, but marijuana may help stop the growth of blood vessels that feed cancerous tumors. Opportunities exist in both cancer treatment and prevention, but more research is needed.
Central nervous system
The effects of marijuana extend throughout the central nervous system (CNS). Marijuana is thought to ease pain and inflammation and help control spasms and seizures. Still, there are some long-term negative effects on the CNS to consider.
THC triggers your brain to release large amounts of dopamine, a naturally occurring “feel good” chemical. It’s what gives you a pleasant high. It may heighten your sensory perception and your perception of time. In the hippocampus, THC changes the way you process information, so your judgment may be impaired. The hippocampus is responsible for memory, so it may also be difficult to form new memories when you’re high.
Changes also take place in the cerebellum and basal ganglia, brain areas that play roles in movement and balance. Marijuana may alter your balance, coordination, and reflex response. All those changes mean that it’s not safe to drive.
Very large doses of marijuana or high concentrations of THC can cause hallucinations or delusions. According to the NIDA, there may be an association between marijuana use and some mental health disorders like depression and anxiety. More research is needed to understand the connection. You may want to avoid marijuana if you have schizophrenia, as it may make symptoms worse.
When you come down from the high, you may feel tired or a bit depressed. In some people, marijuana can cause anxiety. About 30 percent of marijuana users develop a marijuana use disorder. Addiction is considered rare, but very real. Symptoms of withdrawal may include irritability, insomnia, and loss of appetite.
In people younger than 25 years, whose brains have not yet fully developed, marijuana can have a lasting impact on thinking and memory processes. Using marijuana while pregnant can also affect the brain of your unborn baby. Your child may have trouble with memory, concentration, and problem-solving skills.
Smoking marijuana can cause some stinging or burning in your mouth and throat while you’re inhaling.
Marijuana can cause digestive issues when taken orally. For example, oral THC can cause nausea and vomiting because of the way it’s processed in your liver. It may also damage your liver.
Conversely, marijuana has also been used to ease symptoms of nausea or upset stomach.
An increase in your appetite is common when taking any form of marijuana, leading to what many call “the munchies.” This is considered a benefit for people being treated with chemotherapy for cancer. For others who are looking to lose weight, this effect could be considered a disadvantage.
THC may adversely affect your immune system. Studies involving animals showed that THC might damage the immune system, making you more vulnerable to illnesses. Further research is needed to fully understand the effects.
Keep reading: What is medical marijuana? “
What marijuana really does to your body and brain
Marijuana’s official designation as a Schedule 1 drug — something with “no currently accepted medical use” — means it’s pretty tough to study.
Yet both a growing body of research and numerous anecdotal reports link cannabis with several health benefits, including pain relief and helping with certain forms of epilepsy. In addition, researchers say there are many other ways marijuana might affect health that they want to better understand.
A massive new report released in January by the National Academies of Sciences, Engineering, and Medicine helps sum up exactly what we know — and, perhaps more important, what we don’t know — about the science of weed.
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Marijuana can make you feel good.
Weed. (Justin Sullivan/Getty)
One of weed’s active ingredients, tetrahydrocannabinol, or THC, interacts with our brain’s reward system, the part that has been primed to respond to things that make us feel good, like eating and sex.
When overexcited by drugs, the reward system creates feelings of euphoria. This is also why some studies have suggested that excessive marijuana use can be a problem in some people — the more often you trigger that euphoria, the less you may feel during other rewarding experiences.
In the short term, it can also make your heart race.
Within a few minutes of inhaling marijuana, your heart rate can increase by between 20 and 50 beats a minute. This can last anywhere from 20 minutes to three hours, according to the National Institute on Drug Abuse.
The new report found insufficient evidence to support or refute the idea that cannabis might increase the overall risk of a heart attack. The same report, however, also found some limited evidence that smoking could be a trigger for a heart attack.
Weed may also help relieve some types of pain …
Pot also contains cannabidiol, or CBD — and this chemical, while not responsible for getting you high, is thought to be responsible for many of marijuana’s therapeutic effects such as pain relief or potentially treating certain kinds of childhood epilepsy.
The new report also found conclusive or substantial evidence — the most definitive levels — that cannabis can be an effective treatment for chronic pain, which could have to do with both CBD and THC. Pain is also “by far the most common” reason people request medical marijuana, according to the report.
… like the discomfort of arthritis …
One of the ways scientists think it may help with pain is by reducing inflammation, a component of painful illnesses like rheumatoid arthritis.
A preliminary 2005 study of 58 patients with RA, roughly half of whom were given a placebo and roughly half of whom were given a cannabis-based medicine called Sativex, found “statistically significant improvements in pain on movement, pain at rest, quality of sleep” for patients on Sativex.
Other studies testing both other cannabinoid products and inhaled marijuana have shown similar pain-relieving effects, according to the report.
… or the pain of inflammatory bowel disease.
Some people with inflammatory bowel diseases like Crohn’s and ulcerative colitis could also benefit from marijuana use, studies suggest.
A 2014 paper, for example, describes two studies of people with chronic Crohn’s in which half were given the drug and half were given a placebo. That study showed a decrease in symptoms in 10 of 11 subjects using cannabis, compared with just four of 10 on the placebo. But when the researchers did a follow-up study using low-dose CBD, they saw no effect in the patients.
Researchers say that, for now, we need more research before we’ll know whether cannabis can help with these diseases.
Marijuana may also be helpful in controlling epileptic seizures.
A drug called Epidiolex, which contains CBD, may be on its way to becoming the first of its kind to win approval from the Food and Drug Administration for the treatment of rare forms of childhood epilepsy.
The company that makes it, GW Pharma, is exploring CBD for its potential use in people with Dravet syndrome, a rare form of childhood-onset epilepsy that is associated with multiple types of seizures.
In March, the company came out with phase three trial data that showed the drug had some positive results.
But it can also mess with your sense of balance.
It may throw off your balance, as it influences activity in the cerebellum and basal ganglia, two brain areas that help regulate balance, coordination, reaction time, and posture.
And it can distort your sense of time.
Feeling as if time is sped up or slowed down is one of the most commonly reported effects of using marijuana. A 2012 paper sought to draw some more solid conclusions from some of the studies on those anecdotal reports, but it was unable to do so.
“Even though 70% of time estimation studies report overestimation, the findings of time production and time reproduction studies remain inconclusive,” the paper said.
In a 1998 study that used magnetic resonance imaging to focus on the brains of volunteers on THC, the authors noted that many had altered blood flow to the cerebellum, which most likely plays a role in our sense of time.
Limitations on what sort of marijuana research is allowed make it particularly difficult to study this sort of effect.
Weed can also turn your eyes red.
Since weed makes blood vessels expand, it can give you red eyes.
And you’ll probably get the munchies.
A case of the munchies is no figment of the imagination — both casual and heavy marijuana users tend to overeat when they smoke.
Marijuana may effectively flip a circuit in the brain that is normally responsible for quelling the appetite, triggering us to eat instead, according to a recent study of mice.
It all comes down to a special group of cells in the brain that are normally activated after we have eaten a big meal to tell us we’ve had enough. The psychoactive ingredient in weed appears to activate just one component of those appetite-suppressing cells, making us feel hungry rather than satisfied.
Marijuana may also interfere with how you form memories.
Marijuana can mess with your memory by changing the way your brain processes information, but scientists still aren’t sure exactly how this happens. Still, several studies suggest that weed interferes with short-term memory, and researchers tend to see more of these effects in inexperienced or infrequent users than in heavy, frequent users.
Unsurprisingly, these effects are most evident in the acute sense — immediately after use, when people are high.
According to the new NASEM report, there was limited evidence showing a connection between cannabis use and impaired academic achievement, something that has been shown to be especially true for people who begin smoking regularly during adolescence. (That has also been shown to increase the risk for problematic use.)
Importantly, in most cases, saying cannabis is connected to an increased risk doesn’t mean marijuana use caused that risk.
And in some people, weed could increase the risk of depression …
Scientists can’t say for sure whether marijuana causes depression or depressed people are simply more likely to smoke. But one study from the Netherlands suggests that smoking weed could raise the risk of depression for young people who already have a special serotonin gene that could make them more vulnerable to depression.
Those findings are bolstered by the NASEM report, which found moderate evidence that cannabis use was linked to a small increased risk of depression.
… and it may also increase the risk of developing schizophrenia.
The NASEM report also found substantial evidence of an increased risk among frequent marijuana users of developing schizophrenia — something that studies have shown is a particular concern for people at risk for schizophrenia in the first place.
Regular marijuana use may also be connected to an increased risk of social anxiety.
(SHAWN THEW/AFP/Getty Images)
Researchers think it’s possible that CBD might be a useful treatment for anxiety disorders, and that’s something that several institutions are currently trying to study.
And in general, the recent report thought the evidence that marijuana increased the risk of most anxiety disorders was limited.
However, the authors write that there is moderate evidence that regular marijuana use is connected to an increased risk of social anxiety. As in other cases, it’s hard to know whether marijuana use causes that increase or people use marijuana because of an increased risk of social anxiety.
Most importantly, regular weed use is linked with some specific brain changes — but scientists can’t say for sure whether one causes the other.
In a recent study, scientists used a combination of MRI brain scans to get a better picture of the brains of adults who have smoked weed at least four times a week for years.
Compared with people who rarely or never used, the long-term users tended to have a smaller orbitofrontal cortex, a brain region critical for processing emotions and making decisions. But they also had stronger cross-brain connections, which scientists think smokers may develop to compensate.
Still, the study doesn’t show that smoking pot caused certain regions of the brain to shrink; other studies suggest that having a smaller orbitofrontal cortex in the first place could make someone more likely to start smoking.
Most researchers agree that the people most susceptible to brain changes are those who begin using marijuana regularly during adolescence.
Marijuana use affects the lungs but doesn’t seem to increase the risk of lung cancer.
People who smoke marijuana regularly are more likely to experience chronic bronchitis, according to the report. There’s also evidence that stopping smoking relieves these symptoms.
Yet perhaps surprisingly, the report’s authors found moderate evidence that cannabis was not connected to any increased risk of the lung cancers or head and neck cancers associated with smoking.
Some think marijuana could be used in ways that might improve certain types of athletic performance.
Some athletes, especially in endurance and certain adventure sports, say marijuana use can boost their athletic performance. This may be because of anti-inflammatory or pain-relieving effects that make it easier to push through a long workout or recover from one.
At the same time, there are ways that marijuana could impair athletic performance by affecting coordination and motivation or by dulling the body’s natural recovery process.
Without more research, it’s hard to know for sure how marijuana affects athletic performance.
There’s evidence that marijuana use during pregnancy could have negative effects.
According to the new NASEM report, there’s substantial evidence showing a link between prenatal cannabis exposure — when a pregnant woman uses marijuana — and lower birth weight. There was limited evidence suggesting that this use could cause pregnancy complications and increase the risk that a baby would have to spend time in a neonatal intensive care unit.
There are still so many questions about how marijuana affects the body and brain that scientists say far more research is needed.
Florida police’s online response to the marijuana request went viral (Getty)
Based on the report and conversations with researchers, there are good reasons to think marijuana has potentially valuable medical uses. At the same time, we know that, as with any substance, not all use is risk-free.
More research is needed to figure out how to best treat the conditions that cannabis can help and how to minimize any risks associated with medical or recreational use.
That research is essential so that we know “how best we can use it, what are the safest ways, and what are the real risks,” Staci Gruber, an associate professor of psychiatry at Harvard Medical School and director of the Marijuana Investigations for Neuroscientific Discovery program at McLean Hospital, told Business Insider.
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Read the original article on Business Insider UK. © 2016. Follow Business Insider UK on Twitter.
There’s a lot to be said about that Socratic statement “Everything in moderation. Nothing in excess,” especially when it comes to tripping out on weed.
© Nizam Ergil/Getty Images
Marijuana or cannabis is psychoactive, meaning it’ll screw your mind if you take too much in excess and don’t exercise moderation. You’ve got to get the “high” right and this means self-discipline.
Long-term weed use is a lot more dangerous than it is fun. Ask doctors and they’ll tell you the same thing. A lot of medical studies show the long-term effects on the brain and body make marijuana dangerous to a lot of people.
These long-term issues with weed have to do with THC or tetrahydrocannabinol. THC, which triggers the marijuana high, mimics substances called endocannabinoids the human body naturally produces.
Endocannabinoids control the production of neurotransmitters in the human brain. Neurotransmitters are chemical substances that facilitate communication between the brain and the central nervous system.
Endocannabinoids also relax our muscles, reduce inflammation, protect damaged tissue and regulate appetite and metabolism, among other beneficial functions.
Now here’s where the problem lies. Because THC mimics endocannabinoids, the same physiological effects that arise from the normal application of endocannabinoids are triggered with the use of marijuana, especially in the brain.
This explains why marijuana smokers have memory-loss issues, feel higher levels of pain, have to cope with altered emotions and suffer movement control problems. In other words, THC screws the communication between the brain and the CNS.
One of the most deleterious effects of long-term weed use is loss of memory. This is because cannabis temporarily prevents the brain from creating new memories and learning new things. This type of memory loss takes place in the hippocampus, the region of the brain that regulates short-term memory.
Heavy cannabis users are also at risk of developing false memories, even if these users haven’t smoked pot for over a month, said a study published in journal Molecular Psychiatry.
This finding is one among many suggesting that people who were regular marijuana smokers in their teenage years are more likely to have memory problems as adults. Along this line, another study found teenagers that smoked pot every day for three years had “abnormally shaped” hippocampal regions when they reached their early 20s.
These people “performed around 18 percent worse in long-term memory tests” compared to other test subjects who had never smoked marijuana.
Medical researchers are surprised that there was “such a consistent association with verbal memory for chronic exposure to marijuana,” even when other factors (like cigarettes and alcohol) were accounted for.
The key lesson: moderation in smoking weed will keep you thinking straight.
There’s also a ton of research suggesting that people who smoke marijuana daily for a number of years struggle with cognitive tasks more than those who either don’t smoke cannabis, or who do so infrequently or for shorter periods of time.
Research shows that people who occasionally smoke marijuana and then give up the habit have a lower risk of developing problems with their thinking power and memory.
The body pays a hefty price for long-term weed use. Long-term exposure to smoking can damage the bronchial passages and the lungs, as well.
Studies show regular pot smokers are more likely to have persistent coughs (like tobacco smokers), have trouble breathing and produce excess phlegm and mucus. What marijuana smoking does to respiratory health “has some significant similarities to that of tobacco smoking,” said a study in the Journal of General Internal Medicine.
THC can increase the heart rate by as many as 50 beats per minute, which can last as long as three hours. That’s a lot of unwanted stress on the heart.
Video: Marijuana addiction is real even if it doesn’t affect most users (Newsy)
(Image credit: takito/.com)
Marijuana has a reputation as a relatively harmless drug, but researchers are learning more and more about the effects it may have on the brain.
An increased risk of psychosis, changes in the brain’s reward system and the scrambled neuron signals that may underlie “the munchies” are just some of the many potential effects of marijuana use on the brain.
“The biggest risk related to the use of marijuana is the increased risk of psychosis,” said Dr. Scott Krakower, assistant unit chief of psychiatry at Zucker Hillside Hospital in Glen Oaks, New York. Another significant risk, for those who use marijuana during their teenage years, is an increased likelihood of an IQ drop.
“It is safe enough to say that people who smoke marijuana,” especially when they are young, are more likely have a reduction in their IQ later in life, Krakower told Live Science.
Here’s a look at the recent research on marijuana’s possible effects on the brain.
Marijuana and psychosis
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Multiple studies have linked marijuana use with a higher risk of psychosis, which is a medical term that applies to symptoms that involve losing touch with the real world, such as hallucinations or paranoia. For example, in an analysis published in 2016 in the journal Schizophrenia Bulletin, researchers looked at previous studies of about 67,000 people.
They found that people in the study who used the most marijuana were more likely to be diagnosed with a psychotic mental-health condition, such as schizophrenia, than people who had never used marijuana.
A review published in April 2016 in the journal Biological Psychiatry also found a link between cannabis use and an increased risk of psychosis. “Overall, evidence from epidemiologic studies provides strong enough evidence to warrant a public health message that cannabis use can increase the risk of psychotic disorders,” the authors wrote in the review.
Pot and IQ
(Image credit: OpenRangeStock/)
Teens who smoke pot may be more likely to experience an IQ drop when they are older, research has suggested. In a study of more than 1,000 people in New Zealand, researchers administered IQ tests to the participants twice: when they were 13, and then again when they were 38. The researchers also asked the participants about their drug use throughout the study period.
About 5 percent of the teens in the study had started using pot when they were teens. And it turned out that those who smoked pot at least four times a week and continued to use pot throughout their lives experienced an IQ drop of 8 points by the end of the study, on average.
It’s not clear why pot may have negative effects on people’s IQ, but it could be that teens are more vulnerable to pot’s effects on brain chemistry, Susan Tapert, a neuropsychologist at the University of California, San Diego, who was not involved in the study, told Live Science in a 2012 interview.
Brain size, connectivity
(Image credit: agsandrew/)
Using marijuana for many years may be linked to changes in brain size, research has suggested. In a study published in November 2014 in the journal Proceedings of the National Academy of Sciences, researchers looked at 48 adults who used the drug at least three times a day, for an average of eight or nine years, and 62 people who didn’t use marijuana. It turned out that the people who had been smoking pot daily for at least four years had a smaller volume of gray matter in a brain region called the orbitofrontal cortex, which previous research had linked to addiction.
But the researchers also found that the brains of the chronic marijuana users showed greater connectivity, which is generally a measure of how well information travels between different parts of the brain.
The researchers said they don’t know for sure why chronic marijuana use is linked to these brain changes, but they think it may have something to do with THC (tetrahydrocannabinol), marijuana’s main psychoactive ingredient. This is because THC has been shown to affect cannabinoid receptors, which are involved in appetite, memory and mood, and are present in large numbers in the orbitofrontal cortex.
The brain’s reward system
(Image credit: Stanimir G.Stoev | .com)
The brains of people who have smoked pot for many years may respond differently to certain rewards, compared with the brains of people who don’t use the drug, according to a recent study. In the study, researchers wanted to see whether the brains of 59 chronic marijuana users would respond differently to the photos of objects used for smoking marijuana than they did to the photos of objects that are considered “natural rewards,” such as their favorite fruits.
The scientists found that study participants who had smoked marijuana for 12 years, on average, exhibited greater activity in the brain’s reward system when they looked at photos of objects that they used for smoking marijuana (such as a pipe or a joint) than when they looked at photos of their favorite fruits. In comparison, the people in the control group who did not smoke marijuana did not show greater activity in this brain region when they were shown marijuana-related objects, according to the findings, published in May 2016 in the journal Human Brain Mapping.
“This study shows that marijuana disrupts the natural reward circuitry of the brain, making marijuana highly to those who use it heavily,” study author Dr. Francesca Filbey, an associate professor of behavioral and brain science at the University of Texas at Dallas, said in a statement.
(Image credit: Andrea Danti/)
THC —marijuana’s main psychoactive compound —may increase the level of “neural noise,”or random neural activity in the brain, research suggests. In a 2015 study published in the journal Biological Psychiatry, researchers measured the levels of this random neural activity in 24 people under two conditions: after they had been given pure THC, and after they had been given a placebo.
They found that the people showed greater levels of neural noise after they received the THC, compared with their levels after they took the placebo.
“At doses roughly equivalent to half or a single joint, produced psychosis-like effects and increased neural noise in humans,” senior study author Dr. Deepak Cyril D’Souza, a professor of psychiatry at Yale School of Medicine, said in a statement. The findings suggest that psychosis-like symptoms that people may experience after smoking weed may be related to this neural noise, the researchers said.
Munchies and the brain
Ladies? (Image credit: Angela Aladro mella)
Marijuana may affect certain neurons in the brain that are normally responsible for suppressing appetite, and this effect may explain why people often get very hungry after smoking pot, according to a 2015 study in mice. In the study, researchers stimulated the mice’s appetites by manipulating the same cellular pathway as the one that mediates pot’s effects on the brain, and then observed what was going on in the mice’s brains during the experiment.
The scientists expected that the neurons that typically suppress appetite would be turned off by their efforts to stimulate the rodents’ appetites. But, contrary to their expectations, it turned out that those neurons were actually activated, because they had switched to releasing chemicals that promote hunger, study author Dr. Tamas Horvath, a professor of neurobiology at Yale University, told Live Science in a 2015 interview.
It’s not clear whether it would work the same way in people, the researchers noted. But it has been suggested that using marijuana makes people hungry, they said.
The finding could point to a way to treat the loss of both appetite and weight that some cancer patients experience while undergoing treatments, the researchers said.
Marijuana and the teenage brain
(Image credit: auremar | .com)
Marijuana may affect teenage brains differently than it affects adult brains. However, these effects may not be the same for every user, and they may depend on individual factors, such as genetics, according to two studies published in August 2015 in the journal JAMA Psychiatry. In one of the studies, researchers found that marijuana did not lead to small brain size in teens, in contrast with previous findings that had suggested that the drug does have this effect on the teenage brain.
However, the other study found that, in teenage boys who are genetically susceptible to schizophrenia, pot might alter their brain development in potentially negative ways over time. In that study, the researchers looked at the brains of teenage boys when they were 15, and again when they were almost 19. They found that the boys who smoked pot and carried genes linked to an increased risk of schizophrenia experienced thinning in their brain’s cortex —the outer part of the brain —over the four-year study.
Originally published on Live Science.
Dangers of Marijuana: Long-Term Effects of Pot on the Brain and Body
Marijuana is one of the most popular drugs on the market today. While it may have the impression of being a harmless, fun substance, it is still a drug that changes what goes on in the mind, sometimes with significant consequences. The long-term effects on the brain and body make marijuana a dangerous drug to a lot of people, leading to negative outcomes that don’t show until years later.
Endocannabinoids and What They Do
To understand what marijuana does to a user in the long run, it’s necessary to look at how the drug works in the brain. Marijuana is as effective as it is because its active chemical compound (tetrahydrocannabinol, or THC) mimics substances called endocannabinoids that the human body produces on its own. In the brain, endocannabinoids work by controlling the production of neurotransmitters (chemical substances that facilitate communication between the brain and the central nervous system). In the rest of the body, endocannabinoids relax muscles, reduce inflammation, protect damaged tissue, and regulate appetite and metabolism, among many other functions.
Because endocannabinoids are so important, the brain has readymade receptors for them. Since the THC in cannabis mimics natural endocannabinoids, marijuana is unique among other drugs in that regard. The same physiological effects that arise from the normal application of endocannabinoids are triggered with the use of marijuana, especially in the brain. This is why smokers experience memory issues, augmented levels of pain, and alterations to emotion, pleasure, and movement control.
Marijuana and Memory Problems
The memory issues come from the way marijuana hits the hippocampus, the region of the brain that regulates short-term memory. The effect of cannabis temporarily prevents the brain from developing new memories and learning new things, which is a form of short-term memory.
Researchers who published their findings in the Molecular Psychiatry journal discovered that heavy cannabis users are at risk for developing false memories, even if those users had gone without smoking pot for over a month.
Such a finding is one of a number that suggests people who were regular marijuana smokers in their teenage years are more likely to have memory problems as adults. One such study was published in the Hippocampus journal, which found that teenagers who smoked pot every day for three years had “abnormally shaped” hippocampal regions when they reached their early 20s. Those individuals “performed around 18 percent worse in long-term memory tests,” compared to other test subjects who had never smoked marijuana.
Another study published in JAMA Internal Medicine noted much the same thing, with researchers surprised that there was “such a consistent association with verbal memory for chronic exposure to marijuana,” even when other factors (like cigarettes and alcohol) were accounted for. As past years of marijuana use went up, verbal memory scores went down; expressed numerically, 50 percent of pot smokers tended to remember one fewer word from a list of 15 words. One of the study’s authors worried that “this transient effect” could damage how the brain processes information and how that information is recalled later.
There is much more research that suggests people who regularly smoke marijuana (on a daily basis) for a number of years struggle with cognitive tasks more than those who either do not smoke cannabis or who do so infrequently and/or for shorter periods of time. According to one researcher speaking to Reuters Health, people who smoke marijuana occasionally and then give up the habit (“as most cannabis users do”) have a lower risk of developing problems with their thinking power and memory. Nonetheless, he warned that cannabis is still a drug, and all drugs have some level of harm to them.
From Youth to Adulthood
Aside from memory, other research has looked at the long-term effects of marijuana on dopamine. Production of the neurotransmitter that regulates the pleasure and reward centers of the brain can be compromised if the marijuana use is heavy, according to an article in Molecular Psychiatry found. People who smoked a lot of marijuana tested positive for lower dopamine release in the region of the brain that also controls attention and impulsive behavior. Participants in this study tended to start smoking pot around the age of 16 and became dependent on the substance by 20. In the month before the study was conducted, nearly all users reported smoking marijuana on a daily basis.
A former president of the American Psychiatric Association commented on the study, saying that there is a growing body of evidence that shows that youth use of cannabis develops into problems in adulthood.
Conditions of the Heart
Many of those problems manifest physically, not just psychologically. Healthline explains that since marijuana smoke consists of a number of toxic chemicals (such as ammonia and hydrogen cyanide), long-term exposure to smoking can damage the bronchial passages and the lungs. Regular pot smokers are more likely to have persistent coughs, have some trouble breathing, and produce excess phlegm and mucus from their throats. In fact, the Journal of General Internal Medicine writes that what marijuana smoking does to respiratory health “has some significant similarities to that of tobacco smoking.”
Out of the respiratory system, THC (the active compound in cannabis) exits the lungs and enters the bloodstream, where it moves throughout the body. The National Institute on Drug Abuse cautions that the chemical can increase the heart rate by as many as 50 beats per minute, which can last as long as three hours. Smokers who have heart disease could be at a greater risk of heart attack. Research from the Journal of the American Heart Association suggests that regular marijuana use can not only contribute to the possibility of a heart attack, but also to heart rhythm disorders and stroke, even in young people who have no other risk factors for heart disease.
The point is echoed by the American College of Cardiology, which notes that marijuana causes irregular heart rates and increases the risk of an acute coronary syndrome, which refers to any number of conditions that can be brought on by the sudden interruption of the blood flow to the heart. As a result of this, users who are susceptible to conditions of the heart are taking a serious risk when they smoke marijuana. “Marijuana’s use,” writes the American College of Cardiology, “may be associated with increased mortality in patients with a history of myocardial infarctions (heart attacks).”
Marijuana Use by Pregnant or Nursing Mothers
One of the more distressing risks of long-term effects of marijuana consumption is found in women who are pregnant. Health Canada explains that smoking pot during pregnancy “has been associated with long-lasting harm to the exposed child’s memory.” In addition to potential damage done in utero, cannabis toxins are also carried in breast milk and can be passed to the infant during breastfeeding. The U.S. government’s National Institute of Child Health and Development also advises against the consumption of recreational drugs before pregnancy and during breastfeeding.
Research has been spotty on how much risk cannabis poses to unborn and nursing babies, but an assistant professor of maternal fetal medicine at Washington University nonetheless cautions that “any foreign substance that doesn’t benefit maternal or fetal health should be avoided,” and that women who want to become pregnant or who are already pregnant play it safe when it comes to using marijuana.
More on Long-Term Effects
- Permanent Effects of Drug Abuse
The Risk of Addiction and Testicular Cancer
Listing “What 20 Years of Research Has Taught Us About The Chronic Effects of Marijuana,” Forbes details some other problems that arise with the long-term consumption of cannabis, including:
- The risk of addiction: This is only for one in 10 users; however, for people who start their cannabis use in adolescence, the rate increases to one in six. Withdrawal is also a real problem; discontinuing marijuana intake after prolonged use causes disruptions to daily life through depression, insomnia, anxiety, and loss of appetite.
- The possibility of testicular cancer: A 2015 study published by BMC Cancer found that “current, chronic and frequent cannabis use is associated with the development of .” Doctors were quick to point out that this does not mean that marijuana causes cancer and also noted that testicular cancer is a very rare condition; however, an epidemiologist at the Fred Hutchinson Cancer Research Center in Seattle warned that the relationship between cannabis and the risk of testicular cancer suggests that marijuana carries more risks than immediately evident.
Marijuana has a complicated relationship with sexual libido and function. On the one hand, researchers in the journal of Archives of Sexual Behavior noted that “the illegality of marijuana actually facilitated” the sexual exploits of study participants, with many people using the thrill of the illegal activity (where the purchase and use of cannabis are taboo) to augment their sexual desires and behaviors.
However, animal studies have found that marijuana inhibits the receptors in the erectile tissue of the (animal) penis, according to a study in the Journal of Sexual Medicine, suggesting that cannabis consumption before sex does more to limit sexual function than it does to help it.
Health Risks and Research Restrictions
Even as some research has suggested that long-term marijuana use carries a minimal risk of physical consequences, such as that published in JAMA, scientists still urge caution. “Buyer beware,” write doctors in Massachusetts, saying that there are not as many health risks associated with heavy marijuana use as previously thought, but health risks exist nonetheless.
The sentiment is shared by some smokers themselves. Writing in Vice magazine, one user noted that most of the heavy smokers he knows get high on a regular basis without the stereotypical feelings of laziness or paranoia. But, he warns, “this isn’t always the case.” As time goes on, and as their habit persists, they tend to experience greater levels of social anxiety and general anxiousness after they smoke compared to when they go without. Some went so far as to note that long-term weed use even changed their personalities, making them less outgoing and socially engaged.
One negative effect the JAMA scientists noticed was that people who smoked pot for a long time tended to have worse periodontal (gum) health than others, which in some cases led to the development of gum disease. Those same scientists pointed out that “marijuana use is associated with increased risk of psychotic illness, IQ decline, and downward socioeconomic mobility,” and that even though this particular study did not find much by way of damage to physical health, “heavy recreational cannabis use does have some adverse consequences.”
The Cannabis Consensus
Aside from effects on the brain and body, what else can the long-term consumption of marijuana do? The Clinical Psychological Science journal looked at what cannabis did to midlife economic and social status, and wrote that regular cannabis users experienced downward social mobility and financial difficulties, like struggling with debt and cash flow.
Researching the full effects of the long-term dangers of marijuana on the brain and body is difficult because cannabis is still a Schedule I drug in the United States, which places “significant restrictions” on the scientific examination and investigation that can be done with the substance. Nonetheless, even as the legal and political trend is to move marijuana into the mainstream, the medical community has sounded alarm bells over what years-long exposure to cannabis can do. While doctors were surprised at the JAMA Psychiatry study (with one saying, “You need to be willing to change your mind on these issues.”), the consensus remains clear: Unchecked, long-term marijuana smoking damages the brain’s capacity for memory and cognitive tasks, and increases the risk for the development of a number of health problems later in life.
6 Shocking Ways Weed Can Affect Your Brain
Most people know that smoking marijuana can make you feel spaced out or trigger the need for some munchies, but it also can have some other, lesser obvious consequences on your mind as well. There are a number of shockingways weed can affect you and your brain, and these changes might not be side effects you have heard before. Although marijuana can have medical benefits, it’s also important to be aware of the different ways it can impact your brain.
“Cannabis contains chemicals called cannabinoids that act on receptors in the brain that affect pleasure, memory, thinking, concentration, appetite, and coordination,” Dr. Larissa Mooney, Medical Director at CAST Centers, tells Bustle. “There are also naturally-occurring cannabinoids in the brain called endocannabinoids that act on the same receptors. The primary active chemical responsible for the psychoactive effects of cannabis (such as pleasure, euphoria, relaxation or in some cases anxiety, panic or paranoia) is THC — tetrahydrocannabadiol.”
Although THC can be responsible for these changes in your body, there are also some cognitive risks as well, and these can include everything from memory loss to risk of psychosis. Here are six shocking ways that weed can have a lasting effect on your brain, according to experts.
1. It Can Impair Your Memory
Andrew Zaeh for Bustle
Smoking weed can impair memory attention, and concentration. “For example, impairment in memory occurs because cannabis alters information processing in the hippocampus, which is an area of the brain responsible for memory formation,” says Dr. Mooney. Unfortunately, marijuana’s impact to the brain is cumulative, and THC has been found to influence structures associated with concentration, memory, response time, and thought.
2. It Can Interrupt Your Brain’s Reward System
“Daily cannabis use can disrupt reward circuity, making cannabis use even more desirable to users,” Dr. Aimee Chiligiris, PsyD, a psychologist at Smithers Center at Columbia Doctors Midtown, tells Bustle. “This may interrupt other previous seeking of pleasurable experiences, such as relationships, hobbies, and academics.”
3. It Can Impair Your Ability To Regulate Emotions
Although many people use marijuana to improve their anxiety and depression, it can actually make these issues worse for some people. “Marijuana use and withdrawal may induce anxious and depressive symptoms, and it can also increase symptoms of underlying mental health concerns,” says Dr. Chiligiris. “Recent research demonstrates that long-term use can also impair structures that help to regulate difficult emotions.”
4. It Can Increase Your Risk Of Psychosis
Marijuana use can cause or exacerbate symptoms of psychosis, which may include paranoia or hallucinations, according to Dr. Chiligiris. “Individuals with certain genetic vulnerabilities may be at greater risk to developing psychosis with cannabis use,” says Dr. Chiligiris. “With higher potency THC available, including edibles, individuals may be at risk for more significant or earlier onset of mental health concerns such as psychosis.” While this may not be the case for everyone, it is something to consider.
5. It Can Worsen Your Ability To Learn
“Some research suggests that heavy cannabis as a teen may lead to a reduction of IQ points that may not fully return in adulthood,” says Dr. Chiligiris. One study out of New Zealand found that teens who started smoking before age 18 experienced an average IQ drop of eight points by the time they reached mid-adulthood.
6. It Increases Neural Noise
THC can increase random neural activity in the brain, also known as “neural noise.” Researchers suspect that the psychosis-like symptoms that people may experience after smoking weed can be attributed to this neural activity. This can result in anything from disorganized thoughts to alterations in your perceptions of reality. Neural noise can also interfere with other signals that transmit information in the brain.
Not all effects of smoking weed can be negative, but these are some of the possible effects marijuana can have on the brain.
This post was originally published on July 9, 2018. It was updated on May 29, 2019.
What is marijuana?
Marijuana refers to the dried leaves, flowers, stems, and seeds from the Cannabis sativa or Cannabis indica plant. The plant contains the mind-altering chemical THC and other similar compounds. Extracts can also be made from the cannabis plant (see “Marijuana Extracts”).
Marijuana is the most commonly used psychotropic drug in the United States, after alcohol.1 Its use is widespread among young people. In 2018, more than 11.8 million young adults used marijuana in the past year.1 According to the Monitoring the Future survey, rates of past year marijuana use among middle and high school students have remained steady, but the number of teens in 8th and 10th grades who say they use it daily has increased. With the growing popularity of vaping devices, teens have started vaping THC (the ingredient in marijuana that produces the high), with nearly 4% of 12th graders saying they vape THC daily. In addition, the number of young people who believe regular marijuana use is risky is decreasing.2
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 our DrugFacts: Marijuana as 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, some 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. Some vaporizers use a liquid marijuana extract.
People 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. People call this practice dabbing. These extracts come in various forms, 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 the body, 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 have caused fires and explosions and have been seriously burned from using butane to make extracts at home.3,4
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, they generally feel the effects after 30 minutes to 1 hour.
THC acts on specific brain cell receptors that ordinarily react to natural THC-like chemicals. These natural chemicals play a role in normal brain development and function.
Marijuana over activates parts of the brain that contain the highest number of these receptors. This causes the “high” that people 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
- hallucinations (when taken in high doses)
- delusions (when taken in high doses)
- psychosis (risk is highest with regular use of high potency marijuana)
Marijuana also affects brain development. When people begin using marijuana as teenagers, the drug may impair thinking, memory, and learning functions and affect how the brain builds connections between the areas necessary for these functions. Researchers are still studying how long marijuana’s effects last and whether some changes may be permanent.
For example, a study from New Zealand conducted in part by researchers at Duke University showed that people who started smoking marijuana heavily in their teens and had an ongoing marijuana use disorder lost an average of 8 IQ points between ages 13 and 38. The lost mental abilities didn’t fully return in those who quit marijuana as adults. Those who started smoking marijuana as adults didn’t show notable IQ declines.5
In another recent study on twins, those who used marijuana showed a significant decline in general knowledge and in verbal ability (equivalent to 4 IQ points) between the preteen years and early adulthood, but no predictable difference was found between twins when one used marijuana and the other didn’t. This suggests that the IQ decline in marijuana users may be caused by something other than marijuana, such as shared familial factors (e.g., genetics, family environment).6 NIDA’s Adolescent Brain Cognitive Development (ABCD) study, a major longitudinal study, is tracking a large sample of young Americans from late childhood to early adulthood to help clarify how and to what extent marijuana and other substances, alone and in combination, affect adolescent brain development. Read more about the ABCD study on our Longitudinal Study of Adolescent Brain and Cognitive Development (ABCD Study) webpage.
A Rise in Marijuana’s THC Levels
The amount of THC in marijuana has been increasing steadily over the past few decades.7 For a person who’s new to marijuana use, 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 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.
Higher THC levels may also mean a greater risk for addiction if people 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 people who smoke marijuana frequently can have the same breathing problems as those who smoke tobacco. These problems include daily cough and phlegm, more frequent lung illness, and a higher risk of lung infections. Researchers so far haven’t found a higher risk for lung cancer in people who smoke marijuana.8
- 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. One study found that about 20% of pregnant women 24-years-old and younger screened positive for marijuana. However, this study also found that women were about twice as likely to screen positive for marijuana use via a drug test than they state in self-reported measures.9 This suggests that self-reported rates of marijuana use in pregnant females is not an accurate measure of marijuana use and may be underreporting their use. Additionally, in one study of dispensaries, nonmedical personnel at marijuana dispensaries were recommending marijuana to pregnant women for nausea, but medical experts warn against it. This concerns medical experts because marijuana use during pregnancy is linked to lower birth weight10 and 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. Children exposed to marijuana in the womb have an increased risk of problems with attention,11 memory, and problem-solving compared to unexposed children.12 Some research also suggests that moderate amounts of THC are excreted into the breast milk of nursing mothers.13 With regular use, THC can reach amounts in breast milk that could affect the baby’s developing brain. Other recent research suggests an increased risk of preterm births.27 More research is needed. Read our Marijuana Research Report for more information about marijuana and pregnancy.
- Intense nausea and vomiting. Regular, long-term marijuana use can lead to some people to develop Cannabinoid Hyperemesis Syndrome. This causes users to experience regular cycles of severe nausea, vomiting, and dehydration, sometimes requiring emergency medical attention.14
Reports of Deaths Related to Vaping
The Food and Drug Administration has alerted the public to hundreds of reports of serious lung illnesses associated with vaping, including several deaths. They are working with the Centers for Disease Control and Prevention (CDC) to investigate the cause of these illnesses. Many of the suspect products tested by the states or federal health officials have been identified as vaping products containing THC, the main psychotropic ingredient in marijuana. Some of the patients reported a mixture of THC and nicotine; and some reported vaping nicotine alone. No one substance has been identified in all of the samples tested, and it is unclear if the illnesses are related to one single compound. Until more details are known, FDA officials have warned people not to use any vaping products bought on the street, and they warn against modifying any products purchased in stores. They are also asking people and health professionals to report any adverse effects. The CDC has posted an information page for consumers.
Photo by ©iStock/Adrian Hillman
Long-term marijuana use has been linked to mental illness in some people, such as:
- temporary hallucinations
- temporary paranoia
- 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 depression, anxiety, and suicidal thoughts among teens. However, study findings have been mixed.
Are there effects of inhaling secondhand marijuana smoke?
Failing a Drug Test?
While it’s possible to fail a drug test after inhaling secondhand marijuana smoke, it’s unlikely. Studies show that very little THC is released in the air when a person exhales. Research findings suggest that, unless people are in an enclosed room, breathing in lots of smoke for hours at close range, they aren’t likely to fail a drug test.15,16 Even if some THC was found in the blood, it wouldn’t be enough to fail a test.
Getting High from Passive Exposure?
Similarly, it’s unlikely that secondhand marijuana smoke would give nonsmoking people in a confined space a high from passive exposure. Studies have shown that people who don’t use marijuana report only mild effects of the drug from a nearby smoker, under extreme conditions (breathing in lots of marijuana smoke for hours in an enclosed room).17
Other Health Effects?
More research is needed to know if secondhand marijuana smoke has similar health risks as secondhand tobacco smoke. A recent study on rats suggests that secondhand marijuana smoke can do as much damage to the heart and blood vessels as secondhand tobacco smoke.20But researchers haven’t fully explored the effect of secondhand marijuana smoke on humans. What they do know is that the toxins and tar found in marijuana smoke could affect vulnerable people, such as children or people with asthma.
How Does Marijuana Affect a Person’s Life?
Compared to those who don’t use marijuana, those who frequently use large amounts report the following:
- lower life satisfaction
- poorer mental health
- poorer physical health
- more relationship problems
People also report less academic and career success. For example, marijuana use is linked to a higher likelihood of dropping out of school.18 It’s also linked to more job absences, accidents, and injuries.19
Is marijuana a gateway drug?
Use of alcohol, tobacco, and marijuana are likely to come before use of other drugs.21,22 Animal studies have shown that early exposure to addictive substances, including THC, may change how the brain responds to other drugs. For example, when rodents are repeatedly exposed to THC when they’re young, they later show an enhanced response to other addictive substances—such as morphine or nicotine—in the areas of the brain that control reward, and they’re more likely to show addiction-like behaviors.23,24
Although these findings support the idea of marijuana as a “gateway drug,” the majority of people who use marijuana don’t go on to use other “harder” drugs. It’s also important to note that other factors besides biological mechanisms, such as a person’s social environment, are also critical in a person’s risk for drug use and addiction. Read more about marijuana as a gateway drug in our Marijuana Research Report.
Can a person overdose on marijuana?
An overdose occurs when a person uses enough of the drug to produce life-threatening symptoms or death. There are no reports of teens or adults dying from marijuana alone. However, some people who use marijuana can feel some very uncomfortable side effects, especially when using marijuana products with high THC levels. People have reported symptoms such as anxiety and paranoia, and in rare cases, an extreme psychotic reaction (which can include delusions and hallucinations) that can lead them to seek treatment in an emergency room.
While a psychotic reaction can occur following any method of use, emergency room responders have seen an increasing number of cases involving marijuana edibles. Some people (especially preteens and teens) who know very little about edibles don’t realize that it takes longer for the body to feel marijuana’s effects when eaten rather than smoked. So they consume more of the edible, trying to get high faster or thinking they haven’t taken enough. In addition, some babies and toddlers have been seriously ill after ingesting marijuana or marijuana edibles left around the house.
Is marijuana addictive?
Marijuana use can lead to the development of a substance use disorder, a medical illness in which the person is unable to stop using even though it’s causing health and social problems in their life. Severe substance use disorders are also known as addiction. Research suggests that between 9 and 30 percent of those who use marijuana may develop some degree of marijuana use disorder.25 People who begin using marijuana before age 18 are four to seven times more likely than adults to develop a marijuana use disorder.26
Many people who use marijuana long term and are trying to quit report mild withdrawal symptoms that make quitting difficult. These include:
- decreased appetite
What treatments are available for marijuana use disorder?
No medications are currently available to treat marijuana use disorder, but behavioral support has been shown to be effective. Examples include therapy and motivational incentives (providing rewards to patients who remain drug-free). 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 Cannabis sativa or Cannabis indica plant.
- The plant contains the mind-altering chemical THC and other related compounds.
- People use marijuana by smoking, eating, drinking, or inhaling it.
- Smoking and vaping 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 can have a wide range of health effects, including:
- hallucinations and paranoia
- breathing problems
- possible harm to a fetus’s brain in pregnant women
- The amount of THC in marijuana has been increasing steadily in recent decades, creating more harmful effects in some people.
- It’s unlikely that a person will fail a drug test or get high from passive exposure by inhaling secondhand marijuana smoke.
- There aren’t any reports of teens and adults dying from using marijuana alone, but marijuana use can cause some very uncomfortable side effects, such as anxiety and paranoia and, in rare cases, extreme psychotic reactions.
- Marijuana use can lead to a substance use disorder, which can develop into an addiction in severe cases.
- No medications are currently available to treat marijuana use disorder, but behavioral support can be effective.
For more information about marijuana and marijuana use, visit our:
- Marijuana webpage
- Drugged Driving DrugFacts
This publication is available for your use and may be reproduced in its entirety without permission from NIDA. Citation of the source is appreciated, using the following language: Source: National Institute on Drug Abuse; National Institutes of Health; U.S. Department of Health and Human Services.
This is Your Brain on Weed
Here is a first: a neuroscience experiment on the effects of marijuana smoking on the brain in human participants, on national television. Dr. Lucy Troup, a cognitive neuroscientist from the Department of Psychology at the University of Colorado – Fort Collins, is interested in the effect of marijuana on various measures of brain activity in humans. Brainwaves, eye movements, cognitive ability were all measured by four subjects who smoked marijuana. Studies like this have been performed before, but the interesting part of this story is the fact that it was actually filmed and broadcasted.
Photo source: .com
“Understanding the role that cannabis has to play both medically and recreationally is complex,” Dr. Troup explains. So to get a better understanding, Troup and a team of TV producers from the Canadian Broadcast Corporation (CBC), placed EEG electrodes and eye-tracking glasses onto four participants who smoked pot until they were high. Cognitive tests, such as basic math problems, were administered. Emotional reactions were also monitored, and one participant had to leave the studio because she started to have anxiety symptoms.
This actually is becoming a more and more common occurrence, as the percentage of THC in today’s strains are much higher than they were in the seventies. For example, the strain the participants opted for (Durban Poison) has around 24% THC, up to five times the amount baby boomers were smoking when they were young. This increase in THC percentage is thought to be behind the rise in hospital admissions. Toxicologist and ER doctor Dr. Kennon Heard states that legal cannabis use has increased the number of patients coming in with complaints of abdominal pain, vomiting, and nausea. He also mentions evidence that suggests that marijuana use can worsen mental health disorders, such as anxiety.
Photo source: .com
While the data on the role chronic marijuana use on mental health is fairly conclusive, this increase in the prevalence in gastrointestinal distress seems a bit complexing, considering the overwhelming evidence that particular compounds found in cannabis (particularly cannabinol) appear to alleviate these symptoms. THC, for example, is considered an antiemetic with appetite-increasing effects.
The EEG data were analyzed by Dr. Steven Laviolette of the Schulich School of Medicine and Dentistry at Western University in Canada. According to Laviolette, the brain patterns of all four participants displayed brain activity similar to what you would see in a schizophrenia patient. So does this make marijuana smokers schizophrenic? “Not at all,” says Laviolette, “schizophrenia is a long-term…chronic disease. But they can certainly experience psychotic-like symptoms for a couple of hours.”
This “Reality TV” experiment has enough shock value to garner your attention. However, the results of this study add to the growing body (although still very small) of evidence to determine the ultimate question of whether marijuana is good or bad for you, or whether it lies somewhere in between. Check out the video below, and decide for yourself.
Sources: Youtube.com, PNAS, CMAJ Open, Drug, Healthcare and Patient Safety
In recent years, with the legal status of marijuana shifting, the scientific community has sought to better understand this complex and alluring plant.
With much coverage devoted to the genetic basis of flavor and variety, researchers also aim to explain what marijuana does to a person’s brain.
Functional magnetic resonance imaging (fMRI) allows scientists to glimpse at what a person’s brain activity looks like in the moments that they are thinking thoughts, feeling feelings, and most importantly — for the purposes of this article — getting high.
Let’s take a look at what scientists have found out about the brain of a person before, during, and after they use marijuana.
A 2015 fMRI study shows that the brain’s dorsal striatum, insula, posterior parietal regions, anterior and posterior cingulate, and dorsolateral prefrontal cortex all contribute to what scientists call a “signature” of the decision to smoke cannabis.Bedi et al
What Does a Person’s Brain Look Like When Deciding to Smoke Weed?
Decision-making is a complex process that’s not limited to just one part of the brain. A 2015 fMRI study published in the journal Neuropsychopharmocology centered on 17 participants as they made the decision to smoke. The results suggested that the choice to smoke marijuana is accompanied by a consistent level of activation in a range of brain regions.
Brain imaging showed activation in the subjects’ dorsal striatum, insula, posterior parietal regions, anterior and posterior cingulate, and dorsolateral prefrontal cortex as the person decided to smoke marijuana.
This fMRI fingerprint of the decision to smoke marijuana allowed researchers to distinguish smokers from non-smokers with 100 percent accuracy, suggesting that a person’s brain activates in a distinct pattern when making the decision to smoke marijuana.
The functions of these brain regions tell us a little little bit about the decision to smoke weed, too:
- The dorsal striatum is associated with calculating rewards and making decisions.
- The insula is associated with initiating actions based on a person’s physical state.
- The posterior parietal cortex helps integrate information from different areas of the brain to execute functions
- The anterior cingulate cortex is associated with motivation and goal-directed behaviors
- The posterior cingulate cortex, while not fully understood, is thought to either direct one’s focus of attention or be associated with internally-directed cognition.
- The dorsolateral prefrontal cortex is associated with making decisions that involve calculations of risk or morality.
When you combine all of these brain areas that light up when someone decides to light up, a general picture emerges: When a person decides to smoke weed, they’re essentially performing an analysis of the value they’ll receive by smoking and whether that value is worth pursuing.
If smoking is deemed a good choice, the brain determines how to perform the act. It’s a complex pathway for a simple choice, but it’s a pattern of activation that’s uniquely tied to smoking weed.
What Does a Person’s Brain Look Like When They’re High?
Marijuana enthusiasts know that being under the influence will change your perception of self and the world around you. So even though regular users might not think it’s too bad of an idea to jump behind the wheel stoned or possibly light up on the road, this 2013 study published in the open-access journal PLOS One suggests that THC changes your perception and attention so much that it can be difficult or dangerous to drive.
The study shows the levels of brain activity in people who are performing a “visuo-motor tracking task” that simulates the cognitive processing and visual recognition a person would use to drive.
There are a lot of studies that show the inner workings of the brain of a person who uses marijuana, but there aren’t too many that actually show what it looks like while they’re stoned.
In this case, people who smoked marijuana and attempted the exercise showed a decrease in blood flow to their anterior insula, dorsomedial thalamus, and striatum compared to people who smoked placebo weed.
Now if you recall, the insula is associated with initiating actions based on physical state, and the striatum is associated with reward and decision-making. The dorsomedial thalamus is involved with memory and cognition.
The authors of this study say the decreased activity in these three brain regions suggests that stoned people have issues with saliency detection, which is a fancy term for being able to determine whether what you’re looking at is important. This, along with decreased activity in the dorsolateral prefrontal cortex (an area that, if you remember, lights up before you even smoke and is involved with making decisions based on risk calculations), means that people who are under the influence of marijuana have trouble figuring out what they’re looking at and doing something about it.
While high, you might not realize that your dog is eating your Fritos, or, more dangerously, maybe not react in time to see a pedestrian running in front of your car.
The pattern of brain activation associated with smoking marijuana, in a general sense, suggests that smokers are more interested in their internal world than the external world.
“Subjects are more attracted by intrapersonal stimuli (‘self’) and fail to attend to task performance, leading to an insufficient allocation of task-oriented resources and to sub-optimal performance,” write the researchers. Fascinatingly, some of this brain activity seems to start before a person has even taken the first puff.
Now, let’s see what happens after long-term pot use…
Long-term marijuana use is associated with decreased gray matter in the bilateral orbitofrontal gyri, as well as greater functional connectivity in the orbitofrontal cortex.Francesca M. Filbey et al
What Does a Person’s Brain Look Like After They’ve Smoked Weed for a Long Time?
Researchers have argued about whether long-term marijuana use alters a person’s brain, but at this point, it’s pretty much settled: Chronic marijuana use changes how your brain works. And in a 2014 study in the journal Proceedings of the National Academy of Sciences, researchers compared 48 marijuana users with 62 non-using control subjects to see how people’s brains changed from smoking pot.
Compared to the control group, the smokers had less gray matter in the bilateral orbitofrontal gyri, which are associated with making decisions and processing emotions. But along with this, the marijuana users had more structural connectivity in the orbitofrontal cortex network, which the study authors say suggests that the brain may be trying to make up for the loss of gray matter. The human brain is a complex and dynamically adjusting organ, so any shortcoming in one area can often be partially compensated for in other areas, and this seems to be what’s going on in the brain of a pot smoker.
Is it bad? Maybe, maybe not. Can your brain handle it? From these studies of marijuana smokers, that seems to be the case. But as with any area of research, this is a topic that requires more in-depth longitudinal studies to get a better idea of how marijuana affects the brain, especially in the long-term.
What Happens Inside Your Brain When You Smoke Weed?
For centuries, humans have been using substances to alter their state of mind from caffeine, cigarettes and alcohol, to more extreme drugs. But, as the most commonly-used illicit drug in North America, where does marijuana fit in and how exactly does it affect your brain?
First, we need to understand how the brain functions. Your neurons are the cells that process information in the brain by releasing chemicals called neurotransmitters. From the axon of one neuron to the dendrite of another, they change the electrical charge of the receiving neuron, consequently exciting or inhibiting it. If excited, the signals passes on though. These signals work together, and the effect is quickly compounded into complex configurations within milliseconds, flushing over the entire brain. This is what happens every single time you think, breathe or move.
So what’s going on inside your brain when you smoke pot?
Well, unlike alcohol, which contains molecules nothing like those in our body, cannabis contains molecules that resemble those produced in our very own brains: cannabinoids. Though, naturally, these cannabinoids circulate in much lower quantities compared to the large influx imposed by smoking. Specifically, the chemical tetrahydrocannabinol (THC) resembles a natural transmitter in the brain, that is released when neurons are firing. The neurons temporarily become unresponsive after firing to prevent them from overreacting or being too dominant. This allows your brain to function in a calm and controlled manner, but cannabinoids interrupt this approach in some parts of the brain. Instead, they remove the refractory period of neurons that are already active, and cause your thoughts, imagination and perception to utterly magnify itself.
Once you begin your train of thought it becomes the most significant and profound thing ever. Sound familiar? You can’t see the big picture or even recall your last epiphany because you’re caught up in the momentum of a particular idea, and your neurons keep firing until a new idea takes hold and you go off on a new tangent. If you’re looking for a few laughs, check out our marijuana podcast episode where we talk about the first time we smoked pot.
Interestingly, cannabinoids also affect the levels of dopamine and norepinephrine in your brain, often leading to a sense of euphoria, relaxation, pain modulation, and general enhancement of an experience; though sometimes causing anxiety.
Some people believe smoking marijuana carries no risks. But scientific research shows that there are risks, especially for teens. Marijuana affects a person’s judgment and can impair his or her ability to drive. For those who use it regularly, it can lead to poor academic performance, or even addiction.
So how does marijuana have such a big impact on a person’s ability to function?
Scientists have asked themselves that question for a long time. And after several decades of research they not only figured out how marijuana works, but scientists also discovered an important communications system in the brain and the body, which they called the endocannabinoid system after the cannabis plant from which marijuana comes.
Understanding the science of marijuana began in the mid-1960s with the identification of THC (delta-9-tetrahydrocannabinol) as marijuana’s main active ingredient. Twenty years later, scientists identified the sites in the brain and body where marijuana acts and called them cannabinoid (CB) receptors.
Scientists then discovered the body’s own natural chemicals—anandamide and 2-AG (2-arachidonoyl glycerol)—which also act on CB receptors. These chemicals (called cannabinoids), along with their receptors, make up the endocannabinoid (EC) system.
The EC system is found in many areas of the brain, which explains why it affects so many different body functions. Cannabinoids exert their influence by regulating how cells communicate—how they send, receive, or process messages. Cannabinoids act like a type of “dimmer switch,” slowing down communication between cells.
So how does THC affect the EC system?
When someone smokes marijuana, THC gets into the brain rapidly and attaches to cannabinoid receptors. The natural EC system is finely tuned to react appropriately to incoming information. But THC overwhelms the EC system. It prevents the natural chemicals from doing their job properly and throws the whole system off balance.