weed and math

Smoking Pot Interferes With Math Skills, Study Finds

Smoking Pot Interferes With Math Skills, Study Finds

Researchers studying the effects of marijuana faced an obstacle: they couldn’t create an exact control group. But a change in drug laws in the Netherlands offered a perfect laboratory.


It can be difficult to study the effects of legalizing marijuana. And now, as many states are making marijuana more available, there’s new research from – surprise – the Netherlands that might address an important question. NPR’s social science correspondent Shankar Vedantam is here to explain. Welcome.


SHAPIRO: Tell us about this Dutch study.

VEDANTAM: Well, the Dutch study was addressing a perennial problem that researchers have in studying marijuana laws, Ari. From a research perspective, what you really want to study the effect of a law is to have the law selectively apply to only some people. So if half the people in a city were given access to pot while the other half were not, you could compare the two groups and study the effects that marijuana has. Now, in most places, you don’t have that kind of control group. Either all adults have legal access or no adults have access. The new Dutch study found a way out of the problem. It utilized a natural experiment in the city of Maastricht.

SHAPIRO: And what exactly did they do? How did they get some people who used marijuana and some who couldn’t?

VEDANTAM: So here’s what happened. Recreational pot has been legal in the Netherlands for many years, and since Maastricht is close to the border with Belgium, Germany, France and Luxembourg, lots of tourists come over the border to buy pot in Maastricht. In October, 2011, local authorities felt that tourists from France and Luxembourg were creating a nuisance, so they passed a local ordinance that said pot was legally available only to adults who had Dutch, German or Belgian forms of ID.

VEDANTAM: So now you have some people who could get pot legally and some who couldn’t, and now we have our control group. So an economist, Olivier Marie, decided to study the effect of the policy on students at Maastricht University, and he examined the test scores of more than 4,300 students before and after this partial ban went into effect.

SHAPIRO: All right. So big finale – what impact did smoking pot have on these students?

VEDANTAM: Well, the students who belonged to the groups that were banned from buying marijuana started to do better in their courses. Their test scores.

SHAPIRO: Oh, it’s just what our parents always told us.

VEDANTAM: (Laughter) Their test scores improved by about 5 percent, and the effect was largely driven by improved performance in courses that involve numerical skills. Students started to do better at math.

SHAPIRO: OK, but what about courses that involved abstract painting?

SHAPIRO: Or cooking, no?

VEDANTAM: I think that research is still to be done, Ari.

SHAPIRO: OK. Thanks, Shankar.

VEDANTAM: Thank you, Ari.

SHAPIRO: That’s Shankar Vedantam who regularly joins us to talk about social science research. You can follow him on Twitter at @HiddenBrain. You can also follow this program at @MorningEdition, and I’m at @AriShapiro.

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Researchers studying the effects of marijuana faced an obstacle: they couldn’t create an exact control group. But a change in drug laws in the Netherlands offered a perfect laboratory.


There are many important moments in life that can shape your future. Moments where you find what you’re passionate about, make new friends who care about the same things as you and even earn the trust and freedom that come along with growing up. The decisions you make can help you get closer to the moments that matter most to you. That’s why it’s important to understand how using marijuana before you’re 21 can get in the way.


You might know marijuana as “weed” or “pot.” The marijuana plant produces a mind-altering chemical called THC, (or Tetrahydrocannabinol) which makes you feel “high.” Marijuana can be smoked, vaped, or eaten in foods or drinks. All marijuana products are required to be labeled with this red symbol, so always look for that. A lot of people think that since marijuana is legal, it’s safe for anyone to use. That’s not true, especially for those under the age of 21. Keep reading to learn why.


Young people’s brains aren’t done developing until the age of 25, which means that using marijuana at a young age could get in the way of reaching your full potential. You’re in charge of building your future, so take responsibility for knowing how marijuana can impact your health.

Keep your brain sharp.

Using weed could affect your brain’s development, which can make it harder for you to go after your goals. The part of the brain that is responsible for making decisions is also affected when under the influence of marijuana. It can be harder for you to think clearly and avoid dangerous situations, like staying out of a car that’s being driven by someone that is high or drunk.

You learn and remember better without weed.

Youth who regularly use weed are more likely to have difficulty learning, memory issues and lower math and reading scores. Studies show that these effects can last weeks after using marijuana. You need your brain for everything you do – from school to all of the other activities you enjoy. Do you want to let weed affect that?

It can be hard to quit, so why start?

Weed can be addictive, and if you start using it at a young age, you’re more likely to be addicted later. By choosing not to use, you won’t need to worry about what weed could do to your future.

Signs of addiction include letting marijuana get in the way of everyday life, like school, sports or a job; using more or longer than you planned; and repeatedly trying to quit. If you’re worried about a friend or family member, visit

Weed can slow you down.

Whether you’re an artist or an athlete, you should know that weed can impact how well you do the things you like doing. That’s because weed can affect your reaction time and coordination. This is particularly true when it comes to doing everyday things you love like playing an instrument, skateboarding, and even driving. By not using marijuana, you can focus on the moments that matter most.

Breathe easier and cleaner.

Like smoking cigarettes, smoking weed and secondhand smoke from weed can irritate your lungs and make it harder to breathe. Heavy marijuana smokers can have a cough or wheeze even when they aren’t using. When you choose not to smoke weed, you can breathe easier knowing your body and future are healthier.

Vape products can contain nicotine, marijuana (THC or CBD), or other substances like flavoring agents or additional chemicals. While vaping products have grown in popularity, we have seen outbreaks of lung illnesses linked to vaping. The long-term health effects of vaping are unknown, and as information on the illness emerges, our best advice is to not vape at all. See here for Colorado-specific updates on the outbreak.

Bad reactions can happen.

Weed can sometimes lead to scary reactions, like feeling paranoid and a faster heart rate than normal. It can even cause you to see or hear things that aren’t there. The best way to avoid reactions like these is not to use weed in the first place.

If someone you know has a bad reaction make the responsible decision and stay with them while calling the Poison Control Hotline at 1-800-222-1222. If it seems severe, call 911 immediately. Anyone under 21 who calls for help and stays with the person having the medical issue or bad reaction is protected. The person who had the bad reaction could face legal consequences depending on local law enforcement, but it’s still important to do what you can to keep them safe.


Underage marijuana use can impact more than your health. From legal issues to how it can affect your plans after high school, knowing the risks can help you make the best decisions for your future.

If you’re under 21, it’s illegal.

Colorado weed laws require you to be 21 years or older to use, buy, or have marijuana. But, sometimes medical marijuana can be recommended to people under 21 who have a medical condition. If the person is under 18, they can only get a medical card with two doctor recommendations and parent/guardian approval. If you get caught using marijuana illegally (that includes using someone else’s medical marijuana), you could get an MIP (Minor in Possession). This is the case even if a friend or family member over 21 years old buys marijuana legally and gives it to you. Plus, they could get in serious trouble for sharing it with you because it’s a felony.

Don’t lose the trust of family and friends.

If you get caught with weed, you can lose your parents’ trust and the freedoms you worked hard to earn. Your friends could also feel disappointed or uncomfortable if they find out you’re using marijuana.

Don’t let weed distract you from your team, your club, class, or anything else.

If you’re caught using marijuana, it can seriously impact you at school. You can be kicked off sports teams and banned from extracurricular activities. And, you can even be suspended, expelled, or referred to drug counseling. School is already stressful enough on its own, so to avoid losing things you love, don’t use marijuana in the first place.

Keep your record clean, because driving high can lead to a DUI.

Just like driving drunk, driving high is illegal. Not only could it land you a DUI, but it could also seriously hurt you and other people on the road. Marijuana affects your reaction time, judgment and depth perception, which makes it more dangerous to get behind the wheel. DUIs are also expensive and can cost thousands of dollars in legal fees. You may also spend a lot of hours in court, which could lead to court-appointed community service, probation or possibly even jail.

Marijuana can affect the money you get for college.

If you get caught with marijuana under the age of 21, you could get a Minor in Possession, or MIP. Whether or not college is on your radar yet, an MIP can result in the loss of federal financial aid, meaning you might not get the money you need when the time comes. This applies to a number of different types of financial aid such as Perkins Loans, Pell Grants, Supplemental Educational Opportunity Grants, PLUS Loans and Work-Study Programs.

Your job is too important to get high.

Drug testing is still common for many employers. Many companies do not allow marijuana use, so if you are caught with marijuana at your job or get a DUI or MIP, you could be fired. This could make it harder to be hired in the future. It’s important to know that even if you haven’t used marijuana for several weeks, THC can stay in your system. That means you can test positive even if you haven’t used recently.


Life is already full of challenges. Whether you’re focused on becoming more independent, learning a new hobby, planning for college, or helping your family, using marijuana can make achieving these goals even more challenging. So go out there, focus on what matters to you, and find your moment.

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These are state-level laws regarding retail (non-medical) marijuana. To become fully informed of the laws in your area, review county and municipal retail marijuana laws or consult with legal counsel. If you have questions about retail marijuana and your health, consult with your doctor.

The choices you make when you're young can impact your future. Learn how marijuana could get in the way of your goals.