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How your genes influence your response to cannabis

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Cannabis is able to produce a wide array of experiences in human beings. It can make us sleepy, alter our interactions with people, change our perception of the world, and relieve the symptoms of debilitating diseases. And while different kinds of cannabis products produce different effects, what is even more interesting is that the same cannabis product can produce very different effects among individuals.

For instance, in passing a joint amongst a group of friends, some people may be completely unaffected while others experience intense intoxication of one variety or another depending on marijuana sensitivity and different reactions to weed .

Can some people be immune to weed?

Cannabis exerts its effects through many targets and mechanisms within the brain and body, most notably the CB1 and CB2 receptor sites. These receptors are proteins that are made inside of our cells, and like all other proteins our bodies make, the blueprints for how to build them reside in our DNA. Although the human genome (the collection of all human genes) is strikingly similar across people, random or inherited edits (mutations) in these blueprints are extremely common. Genetic mutations can often be the source of inherited diseases, and they can also account for some of the differences in people’s reactions to cannabis.

Cannabis exerts its effects through many targets and mechanisms within the brain and body, most notably the CB1 and CB2 receptor sites.

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Mutations in the human CB1 receptor (the target for THC and main site of cannabis intoxication) were first observed more than a decade ago. So far, scientists have identified 15 variations of this gene in humans. When the blueprints for the protein are different, the function of the protein is almost always affected.

This means that right now, you’re walking around with one of at least 15 different versions of the CB1 receptor protein. In some cases a CB1 mutation could make you more vulnerable to diseases like anorexia , Crohn’s, or addiction , but in others it could drastically alter your sensitivity to the molecules that bind to it (like THC). This could explain why an individual’s sensitivity to cannabis intoxication could be greater or lesser than the 14 other friends sharing the joint.

There are also at least 11 mutations in the human FAAH gene (an enzyme that breaks down our bodies’ naturally produced cannabinoid molecules), and at least seven mutations in the CB2 receptor . These mutations could have major health implications, and are the subject of intense ongoing research.

But genetic mutations that affect the cannabis experience aren’t restricted to the genes involved in our endogenous cannabinoid system. For example, some people have mutations in the Akt gene (Protein kinase B, not an endocannabinoid-specific gene). This gene can keep cells from dying and inhibit tissue growth and is associated with many types of cancer. People with this mutation are more prone to make errors in judgement and motor responses after consuming cannabis. That’s because the individual’s Akt mutation changes how cannabinoids affect them.

Another important variation outside of the endocannabinoid system is found in the liver. When cannabis is ingested orally (swallowed tincture, capsules, or edibles), it passes through the digestive system and liver before the cannabinoids can get into the bloodstream and brain. The liver contains many enzymes (again, proteins encoded by our DNA) that process many kinds of medications and substances. One of the more notable enzymes in the liver converts delta-9-THC into 11-hydroxy-THC, which is even more potent at activating the CB1 receptor and inducing intoxication. There are virtually countless individual differences in the efficiency and diversity of liver functions that could affect our experience with edible cannabis.

There are virtually countless individual differences in the efficiency and diversity of liver functions that could affect our experience with edible cannabis. Photo by: Gina Coleman/Weedmaps

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The genetic mutations that change our experiences of cannabis may be present from birth, but they can also occur as a result of day-to-day life. Genes get turned off and on almost constantly throughout our daily lives, in response to many stimuli (invading viruses, diet, stress, you name it). At some point in the near future, it might be possible to do a simple DNA test (swabbing the inside of your cheek) to determine what your genes look like, how to solve certain genetic diseases, and what you might be able to expect from using cannabis.

Cannabis and marijuana affects everyone differently. Discover how your genes may influence your body's interaction with marijuana.

Recreational Marijuana FAQ

In this Article

In this Article
In this Article
  • How does marijuana work on the brain?
  • What effects can marijuana have?
  • What are the health effects of marijuana?
  • How does marijuana affect teens?
  • What are the different ways you can take marijuana, and how do they affect you?
  • How do edibles affect you compared to smoking marijuana?
  • How can marijuana affect your ability to drive?
  • If you’re pregnant, how does marijuana affect your unborn baby?
  • Can marijuana use lead to harder drugs?
  • What’s the difference between recreational and medical marijuana?
  • Is marijuana addictive?

More than 20 million Americans on average use marijuana each month, making it the most popular street drug in the country. ElevenВ states — Alaska, California, Colorado,В Illinois, Maine, Massachusetts, Michigan, Nevada,В Oregon, Vermont, WashingtonВ — and the District of Columbia have legalized recreational marijuana. Many other states are considering laws to make it legal.

The number of Americans who are in favor of legalizing recreational marijuana has risen. More than 60%В of people surveyed now support the idea. Most Americans don’t think marijuana is harmful. Yet despite the increasing acceptance, marijuana use does have some risks.

Here’s a look at how marijuana can affect your health.

How does marijuana work on the brain?

When you smoke or eat marijuana, chemicals called cannabinoids are released into your body. One main cannabinoid is THC.

Cannabinoids move from your lungs or stomach into your blood. From there, they travel to your brain and the rest of your body. THC acts on certain receptors in your brain. This creates the “high” some people feel.

What effects can marijuana have?

“Marijuana has a range of effects that vary based on the person and the potency,” says Christian Hopfer, MD, associate professor of psychiatry in the division of substance dependence at the University of Colorado. The more marijuana you use, the longer you use it, and the more THC it contains, the more effects you’ll feel.

In the short term, marijuana can affect your:

  • Ability to think and solve problems
  • Coordination
  • Reaction time
  • Judgment
  • Memory
  • Mood

Over the long term, regular use can lead to:

  • Memory loss
  • Trouble learning and thinking
  • Changes in brain structure
  • Trouble at work or in school

What are the health effects of marijuana?

Marijuana affects your body in many ways. Some of them are:

  • Lung problems, such as a chronic cough and trouble breathing
  • Intense nausea and vomiting
  • Faster heart rate, which may raise your risk for a heart attack
  • Mental health disorders such as depression, anxiety, and psychosis

How does marijuana affect teens?

The effects of marijuana can be even more serious in young people. “There’s a much higher risk in people whose brains are developing — those 25 and under,” says Kevin Hill, MD, assistant professor of psychiatry at Harvard Medical School and director of the Substance Abuse Consultation Service at McLean Hospital. “If you’re a young person and you’re using regularly, there’s a whole host of problems that can occur.”

Regular marijuana use during the teen years has been linked to:

  • Lower IQ
  • Changes to areas of the brain involved with learning, memory, and attention
  • Anxiety, depression, and other mental health problems
  • Dropping out of school
  • Worse performance in college

The ABCD study will help researchers learn more about the effects of marijuana on young people. It launched in 2015 and will follow 10,000 kids from age 9 or 10 into early adulthood to see how drugs, alcohol, and other exposures affect brain development.

What are the different ways you can take marijuana, and how do they affect you?

Smoking is probably the most common way to use marijuana. When you smoke from a joint, pipe, or bong, the heat releases active chemicals from the plant into the smoke, which you breathe in.

Marijuana comes in other forms, too.

  • Vaporization. Similar to an e-cigarette, a vaporizer heats dried marijuana and releases a vapor. This vapor contains THC and other cannabinoids, but without the toxic smoke. It is unknown if this method is less harmful to the lungs than smoking marijuana.
  • Dabbing. In this newer delivery method, you heat and breathe in concentrated cannabis oils that contain up to 80% THC. Dabbing produces a strong high. Its safety is still unknown.
  • Edibles. Marijuana can be baked into foods like cookies or brownies. You can also take it by mouth in an oil, capsule, or tincture.

How do edibles affect you compared to smoking marijuana?

The way you take marijuana affects how quickly your body absorbs the THC and other chemicals. “It’s going to be a more rapid onset of action with an inhaled product,” Hopfer says.

Because edibles work more slowly, there’s a greater chance you’ll take too much. “You take a bite of an edible product and nothing happens. Then you take another bite and another bite, not understanding that it takes time for the effects to occur,” Hill explains. Eating large amounts of marijuana can expose you to dangerously high THC levels.

How can marijuana affect your ability to drive?

Marijuana affects many of the skills you need to drive safely, including your:

  • Judgment
  • Motor skills
  • Reaction time
  • Perception

Your risk of getting into a car accident goes up significantly after you’ve used marijuana. “Marijuana definitely affects your ability to drive, just like alcohol does, but you make different errors,” Hill says.

Alcohol makes you forgetful. You might neglect to check your mirrors or drive over the speed limit. With marijuana, you’re more aware that you’re impaired, so you become overly cautious. “When you’re drunk you run red lights, and when you’re stoned you stop at green lights,” Hill says.

After you’ve used marijuana there’s no way to tell whether you’re safe to drive. “We don’t have the technology to test the amount of impairment with cannabis like we do with alcohol,” Hill says. A breathalyzer test can tell if your blood alcohol level is over the legal limit. No test can tell whether you’re too high to drive.

The best advice is to avoid driving after you’ve used marijuana. Or at least wait a few hours before you get behind the wheel.

If you’re pregnant, how does marijuana affect your unborn baby?

We know the effects of alcohol on pregnancy. Miscarriage, birth defects, low birth weight, and developmental problems are possible. The effects of marijuana during pregnancy aren’t as well known, Hill says.

Early research suggests that children born to mothers who smoked marijuana during pregnancy have more problems with:

  • Emotions
  • Attention
  • Memory
  • Impulsive behavior

THC can also get into breast milk. It’s not clear what effect this might have on a baby’s brain.В Some studies show thatВ marijuana use during pregnancy can cause low birth weight in newborns.

Can marijuana use lead to harder drugs?

One of the biggest arguments against legalizing marijuana is that it is a “gateway” drug. The idea is that smoking marijuana might lead people to use other, harder drugs. There is a link between marijuana use and other drug use. Yet there’s no proof smoking pot drives people into hard drugs. “Just because they happen to use marijuana doesn’t mean they’re going to use opioids in 6 years,” Hill says.

Drug use has many causes, including genes, exposure to drugs at home, and stress. It’s possible that people who are more likely to use drugs take marijuana first because it’s easy for them to get. Most people who use marijuana don’t go on to use harder drugs, according to the National Institute on Drug Abuse.В Find out the truth behind common marijuana myths.

What’s the difference between recreational and medical marijuana?

“There really isn’t a difference,” Hopfer says. “Medical marijuana is just marijuana that a doctor has recommended.” Both contain THC and have the same effects on the brain and body. Medical marijuana is used to treat a number of conditions including seizures, nausea and vomiting from chemotherapy, and pain. But there isn’t much research into how well it works.

Is marijuana addictive?

“There’s no question about it,” Hill says. “Marijuana is both physically and psychologically addictive, but most people who use it don’t become addicted.” Around 9% of adults who use marijuana and 17% of teens will get addicted.

Sources

Arria, A. Psychology of Addictive Behaviors, September 2015.

Drug Policy Alliance: “How Marijuana is Consumed.”

Filbey, F. Developmental Cognitive Neuroscience, December 2015.

Gallup: “In U.S., 58% Back Legal Marijuana Use.”

Hancock-Allen, J. Morbidity and Mortality Weekly Report, July 2015.

Kevin Hill, MD, assistant professor of psychiatry, Harvard Medical School; director, Substance Abuse Consultation Service, McLean Hospital.

Christian Hopfer, MD, associate professor of psychiatry, division of substance dependence, University of Colorado.

Kuzma, E. The American Journal of Geriatric Psychiatry, October 2014.

March of Dimes: “Alcohol during pregnancy.”

The Centers for Disease Control: “What You Need to Know About Marijuana Use and Pregnancy

Meier, M. PNAS, October 2012.

National Institute on Drug Abuse: “Can marijuana use during pregnancy harm the baby?” “Does marijuana use affect driving?” “DrugFacts: Marijuana,” “Is marijuana addictive?” “Is marijuana a gateway drug?” “Is there a link between marijuana use and psychiatric disorders?” “Longitudinal Study of Adolescent Brain Development (ABCD Study),” “Marijuana’s Lasting Effects on the Brain.”

News release, The University of Texas at Dallas.

Substance Abuse and Mental Health Services Administration.: “Marijuana use and perceived risk of harm from marijuana use varies within and across states.”

Governing: “State Marijuana Laws in 2018 Map.”

Learn how recreational marijuana use can affect your health. And find out if it’s addictive.