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Casual marijuana use may damage your brain
April 16th, 2014
09:02 AM ET

Casual marijuana use may damage your brain

If you thought smoking a joint occasionally was OK, a new study released Tuesday suggests you might want to reconsider.

The study, published in the Journal of Neuroscience, is the first to link casual marijuana use to major changes in the brain. And according to the researchers, the degree of abnormalities is based on the number of joints you smoke in a week.

Using different types of neuroimaging, researchers examined the brains of 40 young adults between the ages of 18 and 25 who were enrolled in Boston-area colleges. Twenty of them smoked marijuana at least once a week. The other 20 did not use pot at all.

The marijuana smokers were asked to track their cannabis use for 90 days. All were given high-resolution MRIs, and users and non-users' results were compared.

Researchers examined regions of the brain involved in emotional processing, motivation and reward, called the nucleus accumbens and the amygdala.  They analyzed volume, shape and density of grey matter - where most cells in brain tissue are located.

"I think the findings that there are observable differences in brain structure with marijuana even in these young adult recreational users indicate that there are significant effects of marijuana on the brain," says Dr. Jodi Gilman, lead author and a researcher in the Massachusetts General Center for Addiction Medicine. "Those differences were exposure-dependent, meaning those who used more marijuana had greater abnormalities."

More than a third of the group - seven of the 20 - only used pot recreationally once or twice a week. The median use was six joints a week, but there were four people who said they smoked more than 20 joints a week. None of the users reported any problems with school, work, legal issues, parents or relationships, according to Dr. Hans Breiter, co-senior author of the study and a professor of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine.

"There's a general idea out there that casual use of marijuana does not lead to bad effects, so we started out to investigate that very directly," Breiter said. "This research with the other studies we have done have led me to be extremely concerned about the effects of marijuana in adolescents and young adults and to consider that we may need to be very careful about legalization policies and possibly consider how to prevent anyone under age 25 to 30 from using marijuana at all."

Researchers have long been concerned about the effects of marijuana on the developing brain - teens and adolescents under the age of 25. Preliminary research has shown that early onset smokers are slower at tasks, have lower IQs later in life and even have a higher risk of stroke.

Dr. Staci Gruber, director of the Cognitive and Clinical Neuroimaging Core at McLean Hospital in Boston and a professor of psychiatry at Harvard Medical School, has conducted numerous studies on marijuana use and brain function.

"This data certainly confirms what others have reported with regard to changes in brain structure," she said. "When we consider the findings of the Gilman ... study with our own and other investigations of marijuana use, it's clear that further investigation is warranted, specifically for individuals in emerging adulthood, as exposure during a period of developmental vulnerability may result in neurophysiologic changes which may have long-term implications."

Gruber says we need to take a closer look at all pot users whether they smoke once or twice a week or four or time times a week.

And she had this advice for adolescents: "Don't do it early–prior to age 16. That's what our data suggests, that regular use of marijuana prior to age 16 is associated with greater difficulty of tasks requiring judgment, planning and inhibitory function as well as changes in brain function and white matter microstructure relative to those who start later."

According to the National Survey on Drug Use and Health, in 2012 nearly 19 million Americans used marijuana. It's the most-used illegal drug in the country and use is increasing among teenagers and young adults.

Results of the new study match those of animal studies, authors say, showing that when rats are given tetrahydrocannabinol, or THC - the ingredient in marijuana the gets you high - their brains rewire and new connections are formed.

Gilman thinks when people start to become addicted to substances, their brains form these new connections too.

"The next important thing to investigate is how these structural abnormalities relate to functional outcomes," she said. "Currently we don't know how much marijuana is safe and I think this study shows that we should be cautious about marijuana use in adolescents and young adults whose developing brain may be even more susceptible to cannabis-induced changes."


soundoff (757 Responses)
  1. gmenfan54

    So I guess every member of Congress smokes pot.

    April 16, 2014 at 13:40 | Report abuse | Reply
  2. psion777

    One word- Alcohol! Teens who drink early can and often do die early. I think relative comparison provides for a more unbiased approach to a medical subject.

    April 16, 2014 at 13:44 | Report abuse | Reply
    • Jolly Rancher

      Exactly!!

      April 16, 2014 at 14:00 | Report abuse |
    • Craig

      What a fool. Compare one bad thing to another bad thing. Declare one of them good, because in your mind it is not as bad as another bad thing. (You are living proof the study is correct – your brain is damaged.)

      April 16, 2014 at 14:46 | Report abuse |
    • Really?

      The rest of the worlds teen drink early and don't binge drink nearly as much as any american college student. Alcohol does not equal death?

      April 16, 2014 at 14:47 | Report abuse |
    • chad

      1) Craig, pretty sure you're the fool... Why should alcohol, which does way more damage than Marijuana, mentally and physically, be legal and Marijuana, which people use for medicinal purposes, be illegal?
      2) To "Really?", "alcohol doesn't equal death" you say? feel free to talk to parents who had children die from drinking too much, and dying from alcohol poisoning. With marijuana, you can smoke... and smoke... and eat... and vapor... and eat... and smoke and the only problem you'll have is falling asleep. too much alcohol = poisoning too much marijuana = Sleep.

      April 16, 2014 at 14:59 | Report abuse |
    • wrm

      One has nothing to do with the other in this case. If you can find kids who get their kicks off of hitting each other in the heads with sledge hammers it doesn't make pot any more or less risky.

      April 16, 2014 at 15:56 | Report abuse |
    • Yes!

      That was precisely my first thought reading this article

      April 16, 2014 at 16:19 | Report abuse |
  3. Brickhouse

    Based on a review of the content and quality of most of the pro-doper responses the results of the study appear to be accurate. Users are called "dopers" and "stoners" not because the use of the product makes them more intelligent or better educated; users are identified by these terms because the product renders the user dopey and incoherent. Our society should not legalize a substance that will just produce more stupid, lazy, and indolent persons who will then require a government handout to rectify the inevitable consequences.

    April 16, 2014 at 13:46 | Report abuse | Reply
    • cha ching

      barack obama agrees, that's why he's president, because he never ever smoked weed or did cocaine. choom gang choom gang

      April 16, 2014 at 13:58 | Report abuse |
    • T for Tesla

      Well you can have an opinion, but it appears you want to force your opinion onto others.
      Let me inform you that just because a study says so, does not make it 100% true.
      If that were the case we would of banned butter in the 80's
      Brought it back in the 90's
      And regulated and taxed it in the meantime.

      Take your ideals back to 1950 where you belong.

      April 16, 2014 at 14:01 | Report abuse |
    • agar150

      Paid for by the Republican Party.

      April 16, 2014 at 14:23 | Report abuse |
    • Farnsworth

      Get over yourself.

      April 16, 2014 at 14:47 | Report abuse |
    • Sandydog5

      "Our society should not legalize a substance that will just produce more stupid, lazy, and indolent persons who will then require a government handout to rectify the inevitable consequences."

      You are too late, we already have that, alcohol. Your comment shows you know nothing about cannabis.

      April 16, 2014 at 15:18 | Report abuse |
    • Kuta

      So the researchers found some type of changes in the brain without stating what they were. Labeling them as 'abnormalities' implies negative findings although I'm not sure if that was the researcher's conclusion or the author of this article. I find it interesting there was no data presented on difference in functioning.

      April 16, 2014 at 15:25 | Report abuse |
    • Your mistaken

      all this study says is that smoking weed causes a increase in grey brain matter..its a "abnormally" because it was different from the control group.. tabaco actully causes a decrease in grey brain matter.. Mathematician have a incress in grey brain matter in bolth amount and density... the fact is there have been 1000s of studys done on canibis. . some on this exact subject.. by much more non bias groups than the cristain science monitor... the fact is sir.. canibis is basicky harmless and has significant health benefits such as stress releif and fighting cancer

      April 16, 2014 at 15:27 | Report abuse |
    • chitownmatt

      Brickhouse,
      Throughout history people have invented derogatory names for groups they wished to suppress.
      You are simply using such a derogatory and insulting term as evidence that the sterotype is in fact true.
      It is the same as saying, "they wouldn't call them Stupid Polacks if they weren't stupid."

      April 16, 2014 at 16:12 | Report abuse |
    • Reefer madness

      Right Right Right, who cares , you know what go eat your gmo and drink some fluoride, then go swiw in the fukishima water. On the way back go sniff some diesel exhaust and pop some big pharma pills. Evrything is bad, You start to die as soon as your born.... LEt me have my smoke and leave me the hell alone. Before I come telling you what to ingest ...

      April 16, 2014 at 16:34 | Report abuse |
    • Damon

      Some of us have plenty of intelligence to spare. No need to cling on to it like a drop of water in the desert. Sometimes, intelligence can even be a burden.

      April 16, 2014 at 16:59 | Report abuse |
  4. nobodyiknow

    Smoke damages brains? Who knew?!

    Wait... You mean to tell me that our brains require oxygen, and oxygen deprivation can be harmful?

    What will they tell us next? Food may make you fat?

    April 16, 2014 at 13:47 | Report abuse | Reply
    • gokul

      yes, our brain does require oxygen

      April 16, 2014 at 13:53 | Report abuse |
    • Really?

      It doesn't damage your brain because you are asphyxiating it. THC is absorbed into the blood stream, not smoke.

      April 16, 2014 at 14:48 | Report abuse |
    • Kuta

      Where did the authors make the conclusion that these changes were due to oxygen deprivation? Let me guess, you made them up.

      April 16, 2014 at 15:28 | Report abuse |
  5. Burbank

    Fear mongering "make news". And what does casual use of alcohol or sugar or caffeine do to your brain? They are all mood altering substances.

    April 16, 2014 at 13:48 | Report abuse | Reply
    • Craig

      This kind of dishonesty hurts people. Read up on marijuana and the brains of people under age 25. Read about the dangers for people with depression, bipolar, and schizophrenia. My son took his own life 2 weeks ago. His problem? Depression compounded by abuse of marijuana for 5 years. Everyone was telling him marijuana was harmless, except for mental health professionals and me. He didn't know who to believe.

      April 16, 2014 at 14:38 | Report abuse |
    • Sarah

      No one is saying that any of these substances are good for us. What I don't understand is why these drug users freak out when someone mentions the negative effects? I agree that there are positive uses for it, as well as almost all natural drugs! But the ones who are commenting here, rudely and ignorantly are not using it for medicinal purposes, they are using it because it makes them feel good. I prefer to stay sober, although I have tried it in the past. I would love it if cigarettes were illegal as well, because smoking anything is bad for your body. I have seen loved ones die from use of tobacco products and I don't see how smoking weed is any different. I think it should be legal to use medicinally, just as other potentially harmful drugs are, as long as it is monitored and prescribed by a medical doctor. If they want to legalize it for recreational use, I think it should be reserved to adult use only, 25+ As to not effect developmental processes that happen throughout adolescence.

      April 16, 2014 at 15:21 | Report abuse |
  6. Doosh Limpjaw

    I'll take prescription pain killers over marijuana any day. Oh, I guess I DID!!!

    April 16, 2014 at 13:48 | Report abuse | Reply
  7. William

    I have posted three comments that were not posted so. Cannabis Gets a Super Bowl and the NFL May Approve Medical Marijuana for Players.

    April 16, 2014 at 13:49 | Report abuse | Reply
  8. Nate

    Marijuana has THC and a host of other chemicals. The potency of recreational marijuana is far greater than the marijuana people used in the 1970s. So, the idea that marijuana is some miracle drug that cures or helps everything from headaches to cancer without any side permanent negative side effects is silly. Marijuana is a narcotic and like many narcotics can lead to negative side effects, some which could be permanent.

    I completely support the medical use of marijuana. Many growers can lower the THC and other compounds to appropriate levels to help treat many health problems. I met a wonderful woman that uses marijuana for pain because of horrible car accident she was involved in that left her permanently disabled. If marijuana can help relieve pain and mask symptoms of health problems for even just one person. It should be allowed for medical purposes.

    However, I do not support recreational use of marijuana. We do not allow recreational use of Oxycontin, Codine, and other medicines. We do not allow the legal use of opiates like Heroin and Opium. We do not allow the recreational use of Cocaine. So the line has to be drawn somewhere and marijuana it where I think it should be drawn. I am not for locking up personal users of the drug. I think it is more of a medical problem like alcoholism.

    So allow it for medical use, decriminalize recreational use, and still go after the gangs and drug cartels that sell marijuana.

    I understand that the move to completely legalize it is probably going to win sooner or later. However, I am will not be associated with people that use it for recreation. I would not want to have a doctor or any person I do business with a user of it. Certain professions should be barred from using it. I would not want a paramedic stoned while responding to my house. I would not want a police officer carrying a gun and driving in a car while stoned. I certainly would not want a surgeon smoking a joint to calm his nerves before cutting me open. So even when it becomes legal, I hope certain industry ban their employees from using it, unless it was prescribed by a doctor.

    April 16, 2014 at 13:50 | Report abuse | Reply
    • Not so much

      Marijuana is NOT a narcotic.

      April 16, 2014 at 13:53 | Report abuse |
    • Andre Tanguay

      For medical use, i think that high thc level is better... Why? Just roll mini skinny joint= less smoke, more oxygen, and an effective medicinal level. PS; Excuse ny bad english, i'm french.

      April 16, 2014 at 14:14 | Report abuse |
    • Funny

      " I would not want to have a doctor or any person I do business with a user of it. Certain professions should be barred from using it. I would not want a paramedic stoned while responding to my house. I would not want a police officer carrying a gun and driving in a car while stoned. I certainly would not want a surgeon smoking a joint to calm his nerves before cutting me open."

      I could say the exact same thing about people under the influence of alcohol....

      April 16, 2014 at 14:19 | Report abuse |
    • Chris

      Pot is not a narcotic and is nothing like Codine or Oxycotton. Not being under the influence of a substance is already a requirement at those jobs and most jobs in general. So I do not really see how having legal users of pot is any different than legal users of alcohol. Sounds like your opinions are based in pure ignorance. But this is America so spew your stuipidity on blindly!

      April 16, 2014 at 14:25 | Report abuse |
    • J.M.

      "I understand that the move to completely legalize it is probably going to win sooner or later. However, I am will not be associated with people that use it for recreation. I would not want to have a doctor or any person I do business with a user of it. Certain professions should be barred from using it. I would not want a paramedic stoned while responding to my house. I would not want a police officer carrying a gun and driving in a car while stoned. I certainly would not want a surgeon smoking a joint to calm his nerves before cutting me open."

      Do you spend your days and nights worrying about whether a paramedic, doctor, or police officer is drunk, tweaked out on meth, or half-blind from prescription painkillers? Maybe coked up, or chasing the dragon?

      What makes you wory more about marijuana? What special qualities does it possess that make it more of a threat than these other drugs?

      April 16, 2014 at 14:28 | Report abuse |
    • agar150

      This is a failed argument regarding high THC. It is not like alcohol were you can get trashed. THC after a certain amount does not get you higher. You are just regurgitating lies that the government have been saying for years and putting fear into people who have never tried it. The body gets used to THC very rapidly and after a while even concentrates do nothing to you.

      April 16, 2014 at 14:29 | Report abuse |
    • Sarah

      Funny, you can not do these things while under the influence of alcohol. Really, dear? Yes people do, but it is against the rules and if caught, you will lose your job, license and face time in jail. Not to mention the guilt you would have if you hurt someone for your selfish good time! So yeah think before you type!

      April 16, 2014 at 15:26 | Report abuse |
    • Reefer madness

      Blah blah blah , Everyday we lose brain cells naturally anyway.... You know what Cars are dangerous to your health. They kill 300,000 each year. I say ban them . Before we lose another eater like you. Go back to 1950 ....

      April 16, 2014 at 16:40 | Report abuse |
  9. youtubeit

    youtube "Top Gear challenge Alabama". Watch the video to see who votes GOP these days.

    April 16, 2014 at 13:51 | Report abuse | Reply
    • palintwit

      View any knock out game video to see who votes Democrat these days.

      April 16, 2014 at 14:21 | Report abuse |
    • palintwit

      Fake palintwit @ 14:21.

      April 16, 2014 at 14:44 | Report abuse |
  10. Truth Seeker

    I'm not Pro Marijuana, but this is nothing more than targeted scare tactics by an extremely biased group. The American public won't fall for this. Why are YOU the one's posting this all important information??? Oh, that's right, because it serves your purpose. Where is the TRUE unbiased information/studies/findings???

    April 16, 2014 at 13:52 | Report abuse | Reply
    • preferredduck

      They post this because their corporate sponsors like big pharma, big oil, and big chemical stand to lose money because pot and hemp can be used for plastics and many other things and is biodegradable. This is the whole reason it became illegal in the first place. It's all about money and health.

      April 16, 2014 at 14:10 | Report abuse |
    • William

      It's all about money and wealth.

      April 16, 2014 at 14:20 | Report abuse |
  11. Rosecrance

    This is an important reminder that legalization of marijuana has not made the drug harmless.

    As a medical professional who has been working with teenagers for more than 20 years, I know marijuana can cause damage and create dependence. It often leads to other, more serious substance use. Plus, marijuana today is more potent and stronger than it was 30 years ago.

    Substance use during the teen years can have lasting and permanent effects on teens’ developing brains; there is a correlation between marijuana use and school dropout rates, unemployment, and a feeling of inferiority that impacts self-esteem and motivation.

    Some parents expect their kids to try marijuana as a rite of passage. However, I know teenagers don’t want to become addicted to marijuana or any substance; yet, the attention around the legalization of marijuana may reinforce experimentation. Marijuana use shouldn’t become a societal norm among our teenagers. It is our responsibility to keep this dangerous drug out of children’s hands, whether or not adults have legal access to it.

    Thomas Wright, M.D.
    Chief Medical Officer
    Rosecrance Health Network

    April 16, 2014 at 13:52 | Report abuse | Reply
    • Timmy Suckle

      I kissed my way up to CEO at a health insurance company. Now I take over $1,000,000 of your health care dollars for NO VALUE ADDED to your health care. And that’s just me. Now think about how many other CEOs, VPs, Directors, Managers, etc. are at my company alone. Now multiply that by thousands of others at hundreds of other health insurance companies. From 10 to 25% of your health care dollars go towards administration that adds NO VALUE to your health care. But my company’s PAC dollars will continue to fool you little people into thinking that a single payer system will be bad. Little people like you are so easy to fool. Little people also don’t realize that a single payer system is the ONLY system that would allow little people (as an entire country) to negotiate better health care prices. Little people don’t realize that the Medical Cartels already know that. And that is the reason why the Medical Cartels spend so much PAC money from the hospitals and doctors lobbying against a single payer system. Some little people say that a single payer system would cost you little people more. But if that were true, then wouldn’t the hospitals and doctors WANT that extra money? Yes they would. So why do the Medical Cartels lobby against a single payer system? It’s because the Medical Cartels know it would allow little people to negotiate better health care prices. And that’s what the Medical Cartels are afraid of. Period.
      But us big wigs at insurance companies, hospitals, and pharmacy companies don’t ever need to worry about health care no matter what it costs. We get our health care paid for one way or another by you little people. And we get the little people that work at our companies to contribute to our PACs. And us big wigs say it’s to protect the little peoples’ jobs. But in reality it would be in the little peoples’ best interest to NOT contribute to the PAC. Again, little people are so easily fooled. I won’t ever have to worry about losing my job with so many little people being brain washed by the Medical Cartels’ PAC money. Not only that, the Medical Cartels’ PAC money is used to elect so many republicans that will never allow a single payer system. Republicans have always fought against any meaningful health care reform. But that’s what our Medical Cartels’ PACs pay them for. Politicians can be bought so easily.
      Pretty soon the only people that will be able to afford health care is us big wigs. And that’s the way it should be. We don’t want you little people using up the resources when we need them. And once again, I thank you little people for capping my SS tax at the $117,000 level. Now I only pay 1.17% SS tax and you little people pay 6.2%. Also, thank you for extending my tax breaks. I’m using the extra money on my vacation houses.

      April 16, 2014 at 14:01 | Report abuse |
    • samskwirl

      Go push some pills loser CEO (Criminal Extorting Others)

      April 16, 2014 at 14:07 | Report abuse |
    • James Ison

      I'm sure you don't say that because your primary business is treating addictions... Especially since the science isn;t supporting your little industry on pot anymore and people are waking up to how they have been lied to.

      April 16, 2014 at 14:07 | Report abuse |
    • Mike

      I appreciate your comments but question one analogy. It may that those who drop out of school and so forth are more pre-disposed to smoke marijuana. Not necessarily that smoking causes them to drop out.

      April 16, 2014 at 14:12 | Report abuse |
    • preferredduck

      Spoken like a true chump. You do know the whole gateway drug is false. I know i was in that world. See the pot dealer when illegal branches out and sells harder drugs. So when Joe blow goes to get his herb he has something stronger pushed on him or given to him to try and of course the dealer lies because he sees dollar signs. If people can go somewhere and get only pot then they won't even be around harder stuff to try. I know for me and many others this is how it worked. I went for pot and the peer pressure bs for an hour etc i tried other stuff. I was perfectly happy with pot alone. I have also quit many times when i have to and have 0 problems doing so because it's not addictive like cociane of even oreo cookies now. I am also a pain patient and mess have blown up here to abuse. I know pot helps me take less mess than before so I have a life again. Pot be great legal is bad for your business because people get better and don't need all the crappy procedures that hurt more than help. It's funny when you look at studies from overseas their findings are always different than in the US. Why, look who funds the studies. Follow the money. All these companies wish they could synthesize pit for its media Al use to make billions but it's a plant and they can't

      April 16, 2014 at 14:17 | Report abuse |
    • William

      so can concussions but that has not made playing football illegal.

      April 16, 2014 at 14:22 | Report abuse |
    • Nate

      I love how two people with probably NO medical experience can attack a actual MD with rants against their profession. This Doctor stated pretty obvious facts about a use of a drug and it is funny to see the potheads come out and attack them. This is the problem with the supporters of legalization. They act like there will be no negative side effects on a person and society in general. All legalization does with a hard drug is mask the problems associated with it. Alcohol is a perfect example. The majority of vehicle accidents are caused by people driving under the influence. Domestic Violence has a direct relation with one of the partners being under the influence of a drug at the time. Rapes and assaults on college campuses are directly related to the large amounts of alcohol that is used on those campuses.

      I am fine with the use of medical marijuana, but this doctor brings up logical points about the over use of the drug.

      To all the potheads that want it to be legalized. Stop acting like there is NO negative effects for this drug. Stop acting like it is a miracle drug that can cure everything from headaches to cancer. It is a drug that alters your mind and numbs pain. It has positive and negative effects just like every other narcotic. It can be used effectively to treat symptoms of many diseases, but it has negative side effects.

      April 16, 2014 at 14:28 | Report abuse |
    • J.M.

      Says the man who's paycheck depends on demonizing marijuana...I looked up exactly what Rosecrance is, doc. How many bucks, including taxpayer dollars, would you and your company lose out on if marijauan was legalized, regulated, and taxes like alcohol?

      If you really cared about keeping marijuana out of the hands of kids, you would support legalization.

      April 16, 2014 at 14:34 | Report abuse |
    • Chris

      Alcohol is far more damaging to developing brains. So why is it that you are not opposed to the consumption of liquor at 21 years of age? How is marijuana different or any more damaging to society? Seems to me there is a fair bit of bias here for no reason other than it is programmed into your "Doctor" brain.

      April 16, 2014 at 15:19 | Report abuse |
    • Oh NO!!!

      Now EVERYONE posting here will get a $5,000 charge for that advice!!! Doc, can you prescribe me some weed so I can cope with your overcharges? How much will a prescription for weed cost?

      April 16, 2014 at 15:47 | Report abuse |
    • Is aspirin

      Is aspirin or tylenol the gateway drug for oxycontin? Doc...help me out here.

      April 16, 2014 at 16:32 | Report abuse |
  12. Pookah

    So since I have been smoking pot almost daily (usually not joints – I prefer a pipe) since the age of 17 and am nearly 62 now – maybe I will leave my brain to science.

    April 16, 2014 at 13:54 | Report abuse | Reply
  13. Sequoia

    This study is giving out false information. Did they bother to check if either group drank alcohol or has experimented with any other drug or is currently taking any prescription like any of the antidepressants they give out these days? No. They did not. If what they say were true, then why is my daughter scoring at a 5th grade level when she is in 3rd grade? I used cannabis when I was pregnant because it was the only thing that helped me medically to be able to eat to properly be able to nourish my growing baby in my body, and YES my doctor knew about it and was ok with it. Most others I know who also used cannabis while pregnant, their children are just as super highly intelligent as my dauhter is. When I was in highschool, I was drinking and started to fall behind in math, which was my strongest subject. When I drank less and started to smoke cannabis during lunch, right before my math class, in one semester my grade went from a D to a B+. I was able to focus and concentrate better and always had my homework done in class well before the class was over.....and I was the ONLY one who was able to do this. Keep in mind that this study was financed by the government, so of course they are going to lie and tell everyone the opposite of what the truth really is. Doesn't it seem kinda odd that this study comes out shortly after cannabis is becoming legal in more states? This study is so false and misinforming to the public and people who are not educated on the reality and truth of cannabis.

    April 16, 2014 at 13:55 | Report abuse | Reply
    • samskwirl

      Yeah, I bet many, if not all, were taking X and smoking weed during the study. And a pool of 40 is a poor number of persons to test. It could be the school they are attending that is killing their brains. BTW, we are all dying anyways there is no way around it so smoke the fruck-up.

      April 16, 2014 at 14:09 | Report abuse |
  14. Jake Billington

    All this fuss over a natural plant...

    Poison ivy is a natural plant too. Why not wipe with poison ivy? It's natural. It grows. You can grow it yourself. No need to listen to all those big, controlling outdoor groups that spread lies and misinformation so that we are forced to prop up Big Toilet Paper. Poison Ivy is a terrible name loaded with negative connotations, probably made up for the purpose of promoting the national stigma against touching this perfectly natural plant. It's the Rhus plant, and like all leaf producing, natural plants, we should be able to wipe with it, smoke it, eat the wonderful berries it produces, and enjoy all of its beauty and wonderful gifts.

    April 16, 2014 at 13:58 | Report abuse | Reply
    • samskwirl

      I put that stuff on my nuts, its awesome and your mom likes it when they slap her anus.

      April 16, 2014 at 14:10 | Report abuse |
    • shane

      This may be the worst arguement anyone has ever attempted. You can do whatever you want with Poison Ivy, it is not illegal and no one is going to stop you. I know you though you were being witty but you failed miserably.

      April 16, 2014 at 14:27 | Report abuse |
    • Dooly

      What is your point? Nobody is interested in the medicinal benefits of Poison Ivy but if they are, they can do what they want with it. It is not illegal and there is no multi-billion dollar industry built around it.

      April 16, 2014 at 14:31 | Report abuse |
    • J.M.

      My god! You're right! Poison ivy is terrible! It is the worst thing ever! Why, it even has POISON in the NAME.

      We must immediately launch a War on Poison Ivy! We must wipe out poison ivy with all sorts of chemicals, send heavily armed swat teams to bust down the doors of poison ivy growers, throw people who use poison ivy for jail, longer than murders. And the taxpayer can foot the bill!

      Oh wait, except no one is stupid enough to "use" or grow poison ivy, because it's not a beneficial plant. it's been legal forever, and somehow, mankind has survived.

      April 16, 2014 at 14:37 | Report abuse |
    • Bill

      Oddly enough, if you happen to brush against some Poison Ivy in the forest while out recreating Marijuana is a purported cure for the allergic reaction that Ivy induces. Pretty ironic you bring that up in a post where you mean to slander the Cannabis plant .....

      April 16, 2014 at 14:38 | Report abuse |
    • Jake Billington

      Well however witless my wit turned out to be, it sure got some people hot under the collar. Naturally, I take very seriously the criticisms of pot users. Especially in matters of wit.

      April 16, 2014 at 14:41 | Report abuse |
    • shane

      It would certainly seem like you do care. I have seen you post more than once under this article. You are either bored and looking to get a reaction out of people or paid by one of the anti-cannabis org's to sway the ever increasing support for nation wide legalization of cannabis.

      April 16, 2014 at 15:04 | Report abuse |
    • Jake Billington

      Paid to sway public opinion... I guess pot really does cause borderline pathological paranoia. Add that to the dumb.

      April 16, 2014 at 15:20 | Report abuse |
    • JT

      Is poison ivy illegal? Do you go to jail for possessing it?

      April 18, 2014 at 12:57 | Report abuse |
  15. John Smith

    I am sure with most drugs like THC there are changes in the Brain when used. I am sure that legal drugs do this also including alcohol. The question is will legalizing the drug give better control of who has access (age limits, etc) then there is now. Anyone who thinks a kid who wants to get a joint in the US today can't is delusional.

    April 16, 2014 at 14:05 | Report abuse | Reply
  16. preferredduck

    I find it funny how a doctor says don't give pot to anyone under 25 or 30 but I'm sure his practice or colleagues have prescribed anti depressants and anti psychotics to kids in middle school and they have no data or studies on the long term effect that these drugs have on developing minds. Maybe this is why all the school shootings were don't by someone on these for years who is young. All I know is the cia used these drugs and others in mk ultra or mind control programs. I also wonder who funded this study because that effects the outcome always. If pot is so bad then why does the government hold 25 patents for it being the cure for cancer and a powerful anti oxidant. Don't believe me Google it.

    April 16, 2014 at 14:05 | Report abuse | Reply
    • shane

      Shame on you for using logic and rational in this discussion. 🙂
      This is the confusing part about the cannabis debate. There are soooo many other things that are more destructive(like many of the regularly prescribed pharma drugs) and worthy of societies energy that we could be discussing than Cannabis. Nobody is denying there are adverse effects to Marijuana use, there are for just about anything but they are so miniscule that decades of study are still bringing extremely conflicting and shady results to the table.

      April 16, 2014 at 14:13 | Report abuse |
  17. EL

    Of course such a study is needed to further misrepresentations about cannabis. I identify as a "stoner", but also I'm a 4.0 student about to graduate from a university college. I believe smoking actually HELPS me in MANY aspects of my life. Clearly not every stoner is stupid, lazy, incoherent or irresponsible.

    April 16, 2014 at 14:06 | Report abuse | Reply
  18. Dave

    CNN say hello to straw man...

    Totally agree with others that this study really is not very scientific without isolation of only this activity. The problem with studies involving college kids is how much other dumb stuff are they doing? Alcohol – definitely; hard drug use – possible; prescription pill use – almost guaranteed during finals!

    April 16, 2014 at 14:09 | Report abuse | Reply
    • samskwirl

      Dude I just slammed like 5 four locos and chugged a case of red bullz durrrr durrrr

      April 16, 2014 at 14:12 | Report abuse |
  19. jacomsinger@gmail.com

    This study is leaving out wether any of these students are drinking coffee, energy drink, alcohol, or on some type of antidepressants which many students these days are on. It is a surprisingly unscientific study.

    April 16, 2014 at 14:11 | Report abuse | Reply
  20. rjakobson

    I find the responses to this article very interesting. Everything from someone asking if they had bothered to check if either group consumed alcohol or experimented with other drugs or prescriptions (which if they had checked the link to the study they could have researched that before asking), to people saying essentially that caffeine, alcohol etc., are also just as bad for you (which is a logical fallacy that has nothing to do with the point).

    It's a study. It was published for peer review. That means all they're doing is putting their discoveries out there for others to research, evaluate, and if possible verify. That's all.

    The fact that this is a study that provides results many here disagree with should not cause this kind of knee jerk reaction from people. By the same token, if we have learned anything from cigarettes and studies we cannot blindly ignore the results just because we don't like them. For years people ripped apart studies on cigarettes with arguments like "well alcohol is just as bad or worse...", and all of the same agitated commentaries I see here today.

    If marijuana does in fact effect peoples brain functioning – we need to understand why, and if there is a severely negative issue, and if in fact there is an issue we have not until now studied in depth we need to address it.

    The truth is the so called pro-hemp groups out there are very well funded and have a vested interest. Marijuana has always been a lucrative business, long before it was legal. The fact that people are now seeing potential billions in profits from legalizing and selling it over and above the already lucrative illegal business trade with marijuana is something that makes me suspect of groups who immediately dismisses research like this.

    April 16, 2014 at 14:13 | Report abuse | Reply
    • J.M.

      And there are billions upon billions of dollars currently being made locking people up in private prisons, tons of drug testing, drug treatment (adults who get caught with one singular joint, getting forced into "treatment" to get out of jail time), not to mention all the non-taxed, blood-tainted profits enjoyed by criminal cartels.

      It makes me suspect groups that immediately put out and rally behind research like this. The timing is VERY convenient. People would rather continue to ruin lives and waste a trillion dollars on an ineffective drug war that ruins lives and produces no positive benefits than to legalize, regulate and tax marijuana.

      April 16, 2014 at 14:23 | Report abuse |
  21. ME

    I thought Gupta pronounced weed the medical miracle to cure all disease, end world hunger an establish everlasting peace.

    April 16, 2014 at 14:14 | Report abuse | Reply
  22. J.M.

    Hmmmm..anyone do a Google search on the damage alcohol causes to teenaged brains?

    https://www.google.com/search?q=alcohol+damages+teen+brains&oq=alcohol+damages+teen+brains&aqs=chrome..69i57j0l5.4657j0j8&sourceid=chrome&es_sm=93&ie=UTF-8

    How about doing a Google search on smoking tobacco and it's affects on teenaged brains.

    https://www.google.com/#q=smoking+tobacco+damages+teenage+brains

    Caffeine, anyone?

    https://www.google.com/webhp?tab=ww&ei=6MhOU6rLOsLnsASG7ILACw&ved=0CBkQ1S4#q=caffeine+damages+teenage+brains

    Clearly, marijuana is no worse than either of these substances. And you can eat or vape marijauan, you don't need to smoke it.

    I'm not saying pot is harmless, but this is more alarmist bullcrap put out by the Pro-Prohibitionist forces running scared about having to get a real job instead of fleecing the American taxpayer.

    The only thing we can say is that all mind-altering drugs, caffeine, tobacco and alcohol included, are not great for teenagers.

    DUH!

    April 16, 2014 at 14:17 | Report abuse | Reply
  23. dodo

    if it helps people and they can't patent it they will try to bash it to the ground untill they scare everyone. sorry guys know one believes your BS!!! If you are lazy your lazy, if your ambitious then your ambitious.. I did a study had one side of the study drink 1oz 151 every half hr, and put together a car. the other half smoked a joint every half hr... guess who did the least damage and put the car togeter correctly... not the ones drinking 151..

    April 16, 2014 at 14:17 | Report abuse | Reply
  24. Trent

    How come there's no mention of who funded the study? That's a MAJOR red flag, and makes me doubt the findings.

    April 16, 2014 at 14:18 | Report abuse | Reply
    • WinterWarlock

      Trent – it's in the link to the paper...it was funded by the Office of National Drug Control Policy, Counterdrug Technology Assessment Center, so your fear is probably right...it was biased by the funding source.

      April 16, 2014 at 14:41 | Report abuse |
  25. Loathstheright

    60 years old, extreme high tech field, most people can't even follow what I do I have been enjoying weed since I was 16, it hasn't been a problem at all. My field has me thinking on so many levels that most people could never even comprehend how I follow it all, and I am still learning more every day. Weed effects different people in different ways, mine has been very positive.

    April 16, 2014 at 14:28 | Report abuse | Reply
    • Look!

      There's a squirrel!!!

      April 16, 2014 at 15:59 | Report abuse |
  26. Katie

    I wonder what pills do to your brain, and why they are pushed on to young adults every single day, all day long!

    April 16, 2014 at 14:29 | Report abuse | Reply
  27. Griffin

    I think Marijuana use may be more prevalent in certain parameters of people that carry personality/lifestyle traits that attract them to the use of Marijuana which are (indirectly) linked to things such as "having lower IQs" or "being slow at tasks." In this aspect we can say that doctors and 4.0 gpa students smoke marijuana without damage but the statistics are skewed because many of these high functioning people may have (in general) a more straight edge personality type and stay away from drugs. Also, changes in the brain don't necessarily mean BAD.

    April 16, 2014 at 14:32 | Report abuse | Reply
  28. 58Sage

    I would take issue with this researcher as it definitely sounds like she had an agenda going in. The changes she says she detects in the brain? Perhaps some of that "damage" or re-wiring is simply changing the brain and not necessarily for the worse in every case.
    When I started to smoke somewhat regularly, my grade point average went from 2.8 to a 4. I became not nearly as withdrawn, became social and socially acceptable, became much more aware of my world – in other words, what others would consider normal.
    I've been smoking for about 40 yrs. now and have never had any negative issue ever arise from it. I'm normally a very nervous, depressed, angry person due to what I later discovered in therapy to be child abuse. Marijuana has relieved those symptoms and allows me to be calm, personable, competent and thoughtful.
    I went for14 years on many different types of pills and they only dulled me and gave me countless other side effects. For these reasons, I cannot condemn anyone who would indulge.
    And you can really only get so high;- anyone can become drunk beyond reason and kill themselves and/or others with no conscience thoughts at all. I've never seen nor would believe another's getting high could change a person into one that would do that.

    April 16, 2014 at 14:33 | Report abuse | Reply
  29. WinterWarlock

    Click the link to the paper – the study was funded by the "Office of National Drug Control Policy, Counterdrug Technology Assessment Center" – would you expect the research to show any other result knowing that?

    April 16, 2014 at 14:40 | Report abuse | Reply
  30. Ric

    of course! you dopers are losers and will drag everyone else down to your sick addicted level. and you have no conscience what exposing young people to more dope, the damge to THEM it will continue to do.

    you people are disgusting and LOSERS!!! doper pukes!

    April 16, 2014 at 14:41 | Report abuse | Reply
    • Loathstheright

      So says the supreme loser.

      April 16, 2014 at 14:47 | Report abuse |
  31. James

    Brain changes != brain damage

    Our brains change all the time, even just as we think. This research does not really prove anything.

    April 16, 2014 at 14:41 | Report abuse | Reply
    • Craig

      Keep on hitting the bong and check back with me in 20 years. The reason Cheech and Chong have been funny for 40 years is that they portray the truth: pot makes you dumber.

      April 16, 2014 at 14:43 | Report abuse |
    • Sandydog5

      Give me a break, In real life Cheech & Chong are both successful old men. In real life they use cannabis.

      April 16, 2014 at 15:27 | Report abuse |
  32. Jake Billington

    Slander the Cannabis plant? Jeepers...

    Why don't you try the experiment of smoking weed and rubbing yourself with poison ivy. Let's see how well it works. I'm afraid to ask for evidence though, regardless of the results...

    April 16, 2014 at 14:44 | Report abuse | Reply
  33. Ed Campbell

    Really amazing punchline given the findings. The article above states "None of the users reported any problems with school, work, legal issues, parents or relationships, according to Dr. Hans Breiter, co-senior author of the study and a professor of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine."

    No correlation between the observations in brain region changes and ANY BEHAVIORAL MEASUREMENT of BRAIN FUNCTION is provided. Where did the word DAMAGES come from. These results are just as consistent with the idea that Marijuana use improves brain function as it is with damage. Interesting study, really questionable reporting

    April 16, 2014 at 14:47 | Report abuse | Reply
  34. chitownmatt

    A study of 60 people over 90 days.?.?.?

    Let us know after you have completed a study of 6000 people over 9 years.

    Also, I find the fact that they had a control group of 20 that 'didn't use pot at all' very very suspect. When I was in college in Boston 15 years ago, it would have been totally impossible to find 20 students that didn't use pot over a 90 day period. 😉

    April 16, 2014 at 14:50 | Report abuse | Reply
  35. Corporate Interests INFLUENCE you

    Don't believe the HYPE, people have been using cannabis for MILLENIA!!! With NO ILL EFFECTS, this is total bull and WHO AGAIN is funding this "research?

    BIG PHARMA?? Global corporations? Who....

    April 16, 2014 at 14:54 | Report abuse | Reply
  36. shelbey

    i am 17 and i had many issues, chronic depression, severely damaged spinal column, pain every day all day, severe social anxiety and no motivation whats so ever in any way especially in academic surroundings. i started smoking when i was 14, and i began to be happier around my peers, i made friends. i wasnt in so much pain, i went out and did things, when i had straight F's i turned around and started getting A's and B's. i grew a sense of confidence and i started to draw and paint. im now a apprentice carpenter and will soon be working in the union making 18.65$ an hour installing solar panels. i now know a solid plan to get me through life when before all i wanted to do is sit and waist away. my spine has become more aligned and my social state has blossomed. im now a better me

    April 16, 2014 at 14:56 | Report abuse | Reply
  37. Safety first

    Let's just ban anything and everything potentially harmful to anyone! Let's do it now!!!

    April 16, 2014 at 15:06 | Report abuse | Reply
    • Safety first

      That includes life itself, life can be pretty harmful to some people!

      April 16, 2014 at 15:10 | Report abuse |
  38. Donnie the Lion

    If you don't believe the credibility of the Journal of Neuroscience, I don't know what to tell you. They are highly reputable, and are in the pocket of no one. They are not saying marijuana hasn't been a medical boon to many, many patients.

    April 16, 2014 at 15:14 | Report abuse | Reply
  39. John Illinois

    Get real people! When you were in high school and saw the people that constantly smoked pot you knew they were worse academically and generally lazy/no motivation....all they worried about was their weed. You do not need a study for this.....you already saw it! Hopefully all of the liberals will just keep smoking their weed until they fry their brains and then no one else will have to worry about them!

    April 16, 2014 at 15:16 | Report abuse | Reply
    • Not a liberal

      Why are you worried about the liberals? Worry about yourself, I'm no liberal I'm also no conservative, I am an independent, I don't need to worry about others I think for myself, I like guns and pot.

      April 16, 2014 at 15:21 | Report abuse |
    • John Illinois

      Not a Liberal, because hopefully it will make the liberals too lazy to go and vote so we do not have any more disasters like the idi 0t in the White House now! Also get Reid, Pelosi and Durbin out of power!

      April 16, 2014 at 15:34 | Report abuse |
    • SM

      Hey John, that is a false stereotype and generally more associated with lower socio-economic standards than with cannabis usage. Just because the smart kids aren't all outside smoking up doesn't mean they aren't, nor does it mean that the ones who do aren't able to achieve success. As with anything, in extremes it will certainly impede your ability to be productive, although the effects of cannabis may be more overt, something as simple as responding to CNN blog posts can impede your personal life as well if done in excess. The journal article being discussed does not and can not comment on whether cannabis use has a lasting effect on cognitive function, motivation, or any other metric of mental acuity. All that is noted here is that structural changes in the brain in those who smoke marijuana is consistent with changes noted in model organism studies, and seems to mimic changes noted in users of other drugs such as nicotine and cocaine to name a couple. In none of these instances have the changes to those structures been interpreted into an actual mental change, and to my knowledge rat studies which looked at chronic (long-term not a slur for marijuana haha) usage at large doses of cannabis did result in the same changes but that the changes were also reversible to varying degrees. So in short this is certainly an interesting paper but it doesn't confirm anything like the stereotype you purport in your post.

      April 16, 2014 at 16:00 | Report abuse |
  40. Yedi

    Too much food kills, too much alcohol kills, too much weed kills….. It goes back to the basic rule… Everything in moderation.

    April 16, 2014 at 15:16 | Report abuse | Reply
  41. Eagle0832

    Just what Obama wants, a youth of drug induced, brain damaged citizens who are dependent on government to exist and will vote Democratic. But of course there will be the "drug harm deniers" who will call any study that criticizes their need for an alternate universe, junk science.

    April 16, 2014 at 15:30 | Report abuse | Reply
    • Sandydog5

      "alternate universe" lolol You don't know cannabis and I never vote Democratic.

      April 16, 2014 at 15:40 | Report abuse |
  42. Maskelyne

    This article calls it "damage". The paper cited called it "abnormalities". At what point does difference become abnormality become damage? I'm a pothead (more or less, off and on, for 47 years), not a neurobiologist, but I read the paper. random observations: 1) The area of the brain affected is associated with both addiction and music. 2) In figure B on page 5532 (density versus usage), the controls show very nearly as much high-density gray matter as the users; the big difference is the lack of low-density scans from users. Are the high-density non-users also abnormal?
    Discuss...

    April 16, 2014 at 15:40 | Report abuse | Reply
  43. Teodor

    This is just expensive negative propaganda.

    Look at this:

    http://www.thedailysheeple.com/this-is-your-brain-on-aspartame_042014

    April 16, 2014 at 15:44 | Report abuse | Reply
  44. Steve

    Kids shouldn't smoke pot. Wow how millions that cost you to figure out. Should someone really get an MRI weekly? And when does 40 people make a study? I can find a lot more then 40 people that smoked pot as kids that are doing fine today. And since we are on the subject of mental lapses I would drug test my proof reader. They might be smoking pot. But what do I know since I smoked as a kid. (If you are irony impaired no I don't think kids should smoke.)

    April 16, 2014 at 15:48 | Report abuse | Reply
  45. J

    This is silly. How many of you, that are defending the stance of the study and vehemently state "marijuana bad" have actually smoked it for any length of time, other than "once or twice and I didn't like it?"

    Now, I'm not saying it’s particularly good for you, but there are several advantages and beneficial properties of cannabis. Endocannabinoids, found in cannabis, are naturally produced by the body. These complex proteins act as cell receptor "blockers" for damaging bacteria, parasites and disease; however, not nearly enough to prevent/cure some of the illnesses that "pot" is prescribed for. Anyway, I could spend all day on this; after all, I wrote my thesis on it.

    The concocted stigma of marijuana began decades ago out of sheer ignorance. Unfortunately, we as a society are too narrow minded to broaden our perspective of its medicinal properties and health benefits. Please read up on studies from proponents as well as opponents and develop a fully informed opinion rather than regurgitating someone else’s. And for the love of all that is true, don't use pot as a scapegoat for other deficiencies.

    By the way, I started smoking @ 13, maintained a 3.88 GPA, wrote a novel, earned my doctorate and fathered 2 children...all before I stopped smoking.

    April 16, 2014 at 15:52 | Report abuse | Reply
    • Sounds

      Sounds like you should have kept smoking.

      April 16, 2014 at 16:02 | Report abuse |
  46. brian

    Then Bill Maher must be an idiot by now. I challenge any non-pothead to match wits with him after he's destroyed his brain from casual use. Put aside his views, you have to concede that he is intelligent enough to stand his ground against O'Reilly or Jon Stewart.

    They do realize that practicing painting every day for 10 years causes changes in the brain too ( not from the fumes mind you ), but because if you practice something enough the brain changes to adapt to what you learn. I know enough artists that smoke a lot, which don't seem in any way stupid, in fact they seem to be able to practice their craft far longer than others can and end up being better. ( I can cite the paper "Practice-related changes in human brain functional anatomy during nonmotor learning." PMID: 8180494 and other research on the subject, there are also ted talks describing this effect )

    I'm not a pothead, never smoked, don't even drink, but it seems like the premise of this research leads to this conclusion. Sounds like more of the garbage used to convince people that not following the socially accepted norms is going to lead to diseases and stupidity. It's obvious that smoking cigarettes, drinking alcohol, even smoking pot is not exactly healthy, but this seems more like propaganda and FUD to support the status quo. The war against pot was actually based on opposition to the hippy peace movement, not on science.

    There is an idea in science that a theory can be proven valid a hundred times, but it only takes one instance to prove it's false. The example is all swans are white is true until you find the black swan, which destroys the theory. Casual use "might" affect the brain, but if it damages the brain, why do we have very smart people ( like Bill Maher ) who don't seem like they are getting stupider year by year. As it is, this article is just claiming swans "might" be white, on a topic they don't know much about.

    April 16, 2014 at 16:05 | Report abuse | Reply
    • Jake Billington

      Bill Maher as an example of why pot doesn't hurt your cognitive function? Are you sure you aren't a user?

      April 16, 2014 at 16:12 | Report abuse |
    • Diane

      Thank you!!! You nailed it

      April 22, 2014 at 17:01 | Report abuse |
  47. JT

    I used to get upset at articles like this, but not so much anymore. It's a bit like when you're doing well but don't get any recognition from anyone else. At first you are upset that nobody pays attention, but sooner or later you realize that you don't care what anyone else thinks. This is how I've evolved with marijuana. At first I used to defend false claims and try to explain to people how they are being misled, but now I just live and let live. Who knows, maybe I am just some sort of anomoly and all my friends are as well. Maybe we really are the only successful, healthy potheads around. Or maybe the people who keep on trying to convince us that it's so harmful are simply wrong. Look at it another way – in any court case there's going to be a side that's completely wrong and will lose – but you don't really fault them for trying either way as it is their right to do so.

    I just think we need to get the law out of it. Let adults make their own decisions.

    April 16, 2014 at 16:09 | Report abuse | Reply
  48. Robert

    Do a study where the person eats cannibus or vaporizes it and then measure brain damage. Nobody said marijuana had no negative side effects.....even water can harm you if consumed improperly or in excess. Stop spreading drug war propaghanda, the facts are that cannabis is no more harmful then alcohol, cigarettes, or caffeine. Its one of only a few drugs that is impossible to overdose or die from. From my personal experiences I can say without a doubt alcohol is WAY more dangerous then alcohol and has gotten me in much more trouble.

    April 16, 2014 at 16:12 | Report abuse | Reply
  49. NatRo

    I love watching all the stone heads up in a fit over this article... LOL... I don't care how loud you scream, being a stone head is not something you put on your resume, but it's definitely something sober people can smell and see in your behavior. Every stoner I met had that same lazy look in their eyes, and call laziness relaxation. You say pot does not do harm??? my high school friend lost sense of direction, can't turn right, his brain cells are damaged beyond fixing... and the other ones I know are losers in every way possible.

    April 16, 2014 at 16:19 | Report abuse | Reply
  50. zazzle

    Who funded the study? Doesn't say, does it? Says who published it, but not who paid for it.

    April 16, 2014 at 16:24 | Report abuse | Reply
    • jon

      probably an nih grant, but why does that matter? do you think these researchers are not legitimate? did you read the study? these are reputable researchers from reputable schools and its published in a reputable journal. there may be some issues with the study, as there are issues with all studies, but that does not make them illegitimate. if you think the nih or whoever funded there research somehow skewed their results in any way, you're way off. we'd all like marijuana to be 100% awesome with no negative effects at all, but that is not realistic. all drugs have positive, neutral and negative effects.

      April 16, 2014 at 17:00 | Report abuse |
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Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love.