Ann MacDonald

Teens who smoke pot at risk for later schizophrenia, psychosis

Teenagers and young adults who use marijuana may be messing with their heads in ways they don’t intend.

Evidence is mounting that regular marijuana use increases the chance that a teenager will develop psychosis, a pattern of unusual thoughts or perceptions, such as believing the television is transmitting secret messages. It also increases the risk of developing schizophrenia, a disabling brain disorder that not only causes psychosis, but also problems concentrating and loss of emotional expression.

In one recent study that followed nearly 2,000 teenagers as they Smoke rises from a marijuana cigarettebecame young adults, young people who smoked marijuana at least five times were twice as likely to have developed psychosis over the next 10 years as those who didn’t smoke pot.

Another new paper concluded that early marijuana use could actually hasten the onset of psychosis by three years. Those most at risk are youths who already have a mother, father, or sibling with schizophrenia or some other psychotic disorder.

Young people with a parent or sibling affected by psychosis have a roughly one in 10 chance of developing the condition themselves—even if they never smoke pot. Regular marijuana use, however, doubles their risk—to a one in five chance of becoming psychotic.

In comparison, youths in families unaffected by psychosis have a 7 in 1,000 chance of developing it. If they smoke pot regularly, the risk doubles, to 14 in 1,000.

For years, now, experts have been sounding the alarm about a possible link between marijuana use and psychosis. One of the best-known studies followed nearly 50,000 young Swedish soldiers for 15 years. Those who had smoked marijuana at least once were more than twice as likely to develop schizophrenia as those who had never smoked pot. The heaviest users (who said they used marijuana more than 50 times) were six times as likely to develop schizophrenia as the nonsmokers.

So far, this research shows only an association between smoking pot and developing psychosis or schizophrenia later on. That’s not the same thing as saying that marijuana causes psychosis.

This is how research works. Years ago, scientists first noted an association between cigarette smoking and lung cancer. Only later were they able to figure out exactly how cigarette smoke damaged the lungs and other parts of the body, causing cancer and other diseases.

The research on marijuana and the brain is at a much earlier stage. We do know that THC, one of the active compounds in marijuana, stimulates the brain and triggers other chemical reactions that contribute to the drug’s psychological and physical effects.

But it’s not clear how marijuana use might lead to psychosis. One theory is that marijuana may interfere with normal brain development during the teenage years and young adulthood.

The teenage brain is still a work in progress. Between the teen years and the mid-20s, areas of the brain responsible for judgment and problem solving are still making connections with the emotional centers of the brain. Smoking marijuana may derail this process and so increase a young person’s vulnerability to psychotic thinking. (You can read more about how the adolescent brain develops in this article from the Harvard Mental Health Letter.)

While the research on marijuana and the mind has not yet connected all the dots, these new studies provide one more reason to caution young people against using marijuana—especially if they have a family member affected by schizophrenia or some other psychotic disorder. Although it may be a tough concept to explain to a teenager, the reward of a short-time high isn’t worth the long-term risk of psychosis or a disabling disorder like schizophrenia.

Comments:

  1. Alvaro

    there are many women in the world who suffer from the problem of snuff, but quit smoking is easier when you propose and execute a method to exactly

  2. Scott

    Boy I really must be psychotic, I’m sixty and I’ve been smoking it since I was 17. This research didn’t take people like me into consideration. I must be a miracle case. They need to spend their time researching the other 1,000 dangerous drugs available to today’s teenagers. This substance is the least of their problems.

  3. Gerry

    This is not the only study that states that marijuana can lead to schizophrenia over the years. Sure, there are other factors to consider too, but that doesn’t make the first statement about marijuana less true.

  4. THC.me

    I concur with these commenters:
    “It is funny how researchers curve evidence to find what they want to find.”

    [SARCASM]
    It’s a good thing that the 15,000+ chemical toxins which are allowed to be put into the food supply are all 100% safe and approved.
    [/SARCASM]

    There are numerous other factors that need to be taken into consideration before posting something like this. Especially from Harvard.

  5. Adriana Chitimia

    This facts can be very helpful for all the people.

  6. Cassie Miller

    This article was really amazing and great information are provided. This facts can be very helpful for all the people especially for our youngsters that had been influenced by this kind of doing. For me parents should be blame on this when some teens tend to do this things.

  7. Aaron

    Another study that only SUGGESTS something. Marijuana has been around for as long as the Earth has, if there was any problems brought on by it i’m sure it would be evident.

  8. Fredrick

    It is funny how researchers curve evidence to find what they want to find.

  9. promotekey.com

    Thank you for every other fantastic post. Where else may anyone get that type of information in such a perfect means of writing? I have a presentation next week, and I’m at the search for such information.

  10. pest control

    my friend who is very addict with pot or any kind of drugs is so dangerously looking. I dont typically trust him since he is capable of doing bad things.

  11. ElectroPig Von Fökkengrüüven

    [SARCASM]
    It’s a good thing that the 15,000+ chemical toxins which are allowed to be put into the food supply are all 100% safe and approved.
    [/SARCASM]

    If you look at the Jamaican Cannabis study, which showed that children born of even HEAVY cannabis smoking mothers were actually better off on almost all scales than the children born of mothers who never touched cannabis at all.

    We REALLY need to look at any “pre-designed study” which is released to find out if it was a “designed result”, or whether it was a “result which was discovered.” There is a difference…

  12. john siroky

    I would have to say this news is disturbing. I am a medical marijuana patient, I have been medicating now for 41 years. with so many studies showing little or no ill effects from marijuana use I would have to say I am surprised. as far as the way I feel, I don’t believe I have suffered any mental instability from 41 years of marijuana use. I originally started using marijuana because of mental instability. I am bipolar. from the time I was 13 years old I was being taken to different clinics for evaluation and given different drugs, including thorazine. that stuff works but there isn’t much left, I mean as far as a thought process why you’re taking it. tried several different psych meds, the only thing that truly keeps me in check, and still allows me to be
    me is marijuana. I am not saying no to the paper I am commenting on, I’m simply saying it was exactly the opposite for me.

  13. Perfb

    allow me to substantiate this article, I have a family history of schizophrenia, and experienced it myself after smoking pot as a teen, though luckily symptoms stopped when I stopped, but left some lasting personality disorders. A good book is Mark Vonnegut’s ‘Eden Express’, he describes his own experience with pot, and it is exactly what this article is talking about, though he himself does not make the connection, but anyone familiar with the topic will see the connection on reading the book.

    • Johnathan

      Maybe it’s the family history and has nothing to do with the pot.

    • Aaron

      Dude only like 1 percent of the US population has Schizophrenia. Don’t you think if it did this almost half of the population would have it? The article classifies a heavy user as smoking marijuana 5 times. What about those who smoke 5 times a day? lol. Come on now, don’t be stupid.

  14. Anonymous

    All of this feels contrived. Considering the “share” that Harvard holds in the pharmaceutical industry, of course they’re biased

  15. Christy

    There’s a lot of social bias involved in these sorts of studies. Prior to and throughout most of the 20th century, American Psychiatric Association and the American Psychological Association viewed homosexuality as a mental illness and the one of the past Presidents of the APA approved the widespread use of lobotomies on mental health patients (including alcoholics and other drug addicts). Read more about it here:
    http://articles.sun-sentinel.com/1987-02-23/news/8701120220_1_brain-lobotomy-science

    Can you guess what common drug causes these “psychotic” symptoms: feelings of invulnerability, aggressiveness, and recklessness? This drug could cause people to become extremely violent or promiscuous while under the influence.

    Pill-prescribing pychiatrists can manipulate the parameters of what they consider “psychosis,” but it’s clear that the vast majority of drug-induced “psychosis” that harms both individual and society is caused by alcohol, so why do these martini-drinking, big pharma lapdogs focus so much attention on marijuana?

  16. stan

    I use to smoke alot of marijuana when I was younger. I do not use it any longer. I have a high IQ still , yet I do have anxiety problems now. Also, sometimes I become anti-social. Looking back, the use of marijuana is not really worth it. It may seem fun at the time, but it just makes you stupid. :)

  17. ha ha ha is this april fools day ?

    talk about stating the bleeding obvious ‘people that smoke dope may be at risk of believing the tv is sending out messages’ – well done ann macdonald for discovering what every kid thats smoked pot learnt years ago. thats what pot does, thats why they smoke it ! ha ha ! ridiculous.

    • Claire - UK

      This is a comment made in ignorance that does not appreciate the seriousness of psychotic episodes. The immediate effects of smoking this drug are actually rarely as you have stated too. After seeing the side effects in a friends son, I can only say that the sooner this is fully accepted and (the smarter) teens make more considered choices, the better. This drug wrecks lives. A generation ago, many of us smoked marijuana but the strength was nothing like the “skunk” that is most commonly smoked today. Our poor children are unaware of the dangers thay are exposing themselves to.

    • morola

      i bet your the one taking cannabis

    • Johnathan

      Claire-UK,

      All drugs have side effects, especially the legal ones. What makes marijuana so special? It’s just another excuse to arrest more people for using marijuana and minding their own business. Even the big pharma quacks producing these “scientific” studies admit that much. There’s no evidence that schizophrenia can be pointed to just one thing like marijuana. Every credible researcher on mental illness says it’s often multiple factors. Also I’ve met people with bipolar disorder and other mental illnesses who say that marijuana is the best thing that ever happened to them.

    • Aaron

      Dude, Schizophrenia makes some crazy shit happen to people who have it. Like believing their neighbors are controlling their movements through magnetic waves. I don’t know about you but i’ve never thought the tv was sending me messages haha. Although, it does make things very weird which is a big reason why I smoke(: Lets me escape reality! But once again this is another study that only SUGGESTS something bad about marijuana, although there is nothing PROVEN the suggested facts seem to be enough for skeptics to believe it has negative effects.

  18. Someone

    Thank you for writing.

    This is an excellent article

  19. Cap tn Krunch

    Fire up skitzos and blame society for your problems

  20. Helpmyfriend

    Help my friend age 36 had a pyshotic episode recently; she smoked marijauna as teenager into her early adult hood; her mom has been diagnosed schizophrenic manic depressive disorder. Thanks Caroline for the post. Is there anymore information availble regarding recovery at this late age?

    • Aaron

      Schizophrenia is a hereditary disease which only 1 percent of the US population has. Sorry about whoever has it but I promise you it has nothing to do with pot.

      Someone got schizophrenia and you heard about pot so now your looking for someone or something to blame, you shouldn’t do that..

  21. benbenez

    Your social responsibility is exhibited in this article.
    By reading this article there is a chance of people especially teenagers quitting the habit of using marijuana.

    A vivid description of the after-affects of usage of marijuana in the article may be more effective to the people who read it.

    benbenez

    • Aaron

      This is not FACT! I swear, do you skeptics just skip over the part where it says SUGGESTED? Thats right, SUGGESTED! Like every other negative thing supposedly wrong with marijuana that hasn’t been PROVEN.

  22. joe

    This person who calls themselves Me writes that he or she “Will save me the time.” I am sorry if I wasn’t clear when I wrote that people who smoke marijuana are paraniod, vicious, violent (not all violence is physical), moody, and difficult and also that marijuana is a powerful drug that is becoming more powerful. I should have also mentioned that it promotes narciassitic behavior when the partaker is in their drug induced reality and or psychosis.
    (ie: “saving someone the time” that you don’t even know.”
    In conclusion I mentioned if you like it, smoke it, but don’t lie to yourself. I find people will defend their habits or addictions until they finally call it quits for whatever reason that may be. I personally do not enjoy being around people who are high on marijuana and aviod them when possible. (I smoked alot when I was younger and now I do not enjoy it any longer. It has destroyed alot of people I know and that is probably my biggest dislike.)

    • Aaron

      I know at least 100 people who smoke pot and none of them are violent. Have you ever smoked? Do you know firsthand how it affects you? If not then why bother trying to label how people are when they smoke it. It affects people differently. I am so chill when I smoke.

    • fran .

      im with you this one aaron , not everyone that smokes pot do bad things i have been somking for a while now and i just think that it makes me chill it ease my mind if you want to get real . i like it !

  23. Heather Smith

    This is an eye-opener for me, I will recommend this article to my friends, thanks for posting this.

  24. Me

    I’ll save joe the time. So after about hundreds of years of cannabis use in America shouldn’t we be seeing the effects by now as a large increase in the number of cases ? You cant because it doesn’t exist because its not happening . The government will try anything and use anyone to get the results IT wants. I mean with marijuana being the number 1 crop and all how long can you perpetuate a lie. I would think by now this plant would be shedding light on how memory works as well as psychosis, which it already has they cannot admit they were wrong and have blatantly lied what about all the other ridiculous lies about marijuana how can we begin to believe this story after all the lies already proven to be ridiculous. I feel let down by this appearing in a harvard without any solid evidence, paging Dr. Lester grinspoon

    • Claire - UK

      Using “hundreds of years of history” to conclude that Marijuana is harmless is ignoring one major point. The increased strength (x 30) of the drug over tha past 20 years has seen a significant rise in psychotic mental illness. Todays teens are not smoking “the same marijuana” that the previous generation were.

    • Johnathan

      There’s absolutely no proof that the marijuana most people use is any stronger than 30 years ago. also the more potent the marijuana the much more expensive it is, so fewer teens are less likely to be using that than the commonly used stuff.

  25. Gone

    Being a parent of a 26 year old who has been diagnosed with schizophrenia, and living with us in our home;
    I can safely say Dope is an issue. My son does have a history of smoking dope, he craves it. He enjoys the way it enhances his psychotic thinking. We (his family) are only afraid we or the police are going to find him frozen dead in a ditch. When he is questioned about his thinking, he runs. We fear for his life right now, he is in the midst of an episode as I write. He doesn’t like the way his meds clear his mind of his God like thinking. He believes he will save the world, but can’t if he is medicated. He told me he smoked dope recently, and that is the reason we had no idea he wasn’t taking his meds. All we saw; he was working, coming home tired and sleeping, going out with his girl friend and going to bed so he could get up for work at 4 am. This last week, he has lost a lot of weight, and hasn’t been sleeping. So much for those who think dope will cure aliments. It only hides or distorts them, in this case, makes them worse. Smoking dope is just as bad as drinking liquor, it only suppresses the pain, like taking an aspirin for a headache, It may help the pain, but it doesn’t make the cause go away. I am sick and tired of those who say dope is harmless, more than likely they are high at the time. And I believe this report is accurate.

    • ...

      I am sorry for your kid, but he was most likely to get schizophrenia anyway. Marijuana isn’t harmless, and guess what advil isn’t harmless either. Just like any drug it is going to have side effects. Marijuana’s are just very minor. I am writing this 100% sober also.

  26. joe

    I grew up in a beach enviroment where everyone smoked a lot of weed multiple times a day, everyday. They are all very unstable. Their obvious paranoria makes them violent and vicious. Their moods change with the cycle of the high and they appear happy (first) paranoid (second) and then they are tired (third) as the drug leaves their system, and then they start over again. The drug makes people difficult and moody. However, most drug users know this and don’t care. Weed makes boring routines easier and fun for the user, but perhaps not so enjoyable for his or her coworker unless they to are high. IT IS A DRUG. IT IS BECOMING MORE POWERFUL. If you like it smoke it, but don’t lie to yourself about it.

  27. Priscilla Alexander

    I suspect the association works the other way. That is, people who are genetically disposed to developing schizophrenia or other psychoses are more likely to enjoy the high that marijuana provides. Especially if the data is based on as little as once smoking pot, as this article suggests. I doubt that rare use could precipitate anything. It seems to me, based on my experience smoking pot when I was in my thirties, that smoking it frequently could lower one’s resistance to allow one’s thoughts to move into hallucinations that would otherwise be resisted. I stopped smoking pot because I felt it increased my paranoia, but I never got more paranoid, and the feelings diminished after I stopped smoking pot.

    • Jane Ramberg

      I concur with Ms. Alexander. The data presented in this article does not confirm that use of marijuana increases the risk of schizophrenia. It does appear to indicate an association between marijuana use and schizophrenia. It could be that individuals predisposed to developing this terrible mental illness are also predisposed to craving marijuana. Given Harvard’s status in the medical community, and the vulnerability of individuals suffering from schizophrenia (and their parents), I believe it’s important that the data be more honestly represented.

  28. DD More

    I’ve smoked pot everyday from teen age till age 36 till work drug testing was mandatory and I chose family over pot. It was not addictive and I have a son who turned out great with a college education. I have 3 degrees and this study is fraud…. If you want to become a problem on society, then you will it. I don’t smoke cigs now for 10 years and quit cold turkey. Its not nicotine or tars that’s habit forming… It’s the pure habit of the burn and inhaling to achieve the burn. All my friends are either dead from heart attack or stroke or other mental problems but pot was not a mental burden to the body.

  29. AlanaMiles

    I saw a fascinating David Suzuki documentary out of Canada that examines this connection. Evidently as the plant has been tweaked to have a higher THC content another cannabinoid that balances THC has been reduced to nearly zero. Further, a gene discovered about a decade ago that regulates dopamine has two variants, and one’s susceptibility to marijuana-induced psychosis is dependent on which combination of variants of this gene a person has.

  30. kristin

    dont smoke it not gewd

  31. Caroline

    Keep in mind that nicotine use may also be another confounding factor, one that is surprisingly omitted in these marijuana/schizophrenia studies despite the prevalence of nicotine use among schizophrenic patients. It does not take long at all to get hooked on nicotine (some addiction specialists say it just takes one pack) and many nicotine users start in their early teens. With society pressuring many people to quit or to repeatedly attempt it, the withdrawal symptoms result in a lot of stress and anxiety for people, factors that may contribute to vulnerable persons developing symptoms of schizophrenia at an earlier age. As was posted earlier, according to the following U.S. National Institute of Mental Health website:

    “It is hard for people to quit smoking because it might make their schizophrenia symptoms worse for a while.”

    http://www.nimh.nih.gov/health/publications/schizophrenia-easy-to-read/schizophrenia-easy-to-read.shtml

    I don’t think we should quit anti-smoking campaigns that target youth and the general public just because it may worsen schizophrenic symptoms in vulnerable persons or lead to an earlier onset of such symptoms. Nevertheless, this is something that definitely needs to be addressed in any discussion of mental illness being correlated with substance abuse/use.

    • chaya

      interesting comments.. thank you for the link.. the article is true…I have seen it in my family. I know there are spiritual ramifications and curses as well.. so..i direct people to Bob Larson ministry.

  32. Chris

    Absolute nonsense!

    There are NO studies to support ANY of these claims.

    Genetics, heredity and alcohol are THEE only things on record that are believed to cause psychosis and schizophrenia.

    The science community has long known schizophrenia runs in the family. Out of every person diagnosed with this disease, over 80% have a family history of it. The chemistry and structure changes in the brain, if any, caused by marijuana, are as much an argument against your claims as it is an argument for them.

    Some scientists even say stress is a cause for this disease, being 99% of us experience normal to above normal stresses throughout our lives, how could any study on this claim be legitimized?

    Your claims, not facts, in my opinion, are mostly based on your anti-marijuana views and the fact your university is heavily involved and invested with the pharmaceutical industries. If I’m wrong about both my claims, then I can only attribute this bogus article to bad science and journalism.

    • Terry

      I agree. These sound like a bunch of propaganda studies funded by the DEA. We know that medical marijuana studies were stopped under The Ford Administration in 1976. They banned independent research and research by federal health programs on the use of natural cannabis derivatives for medicine for years. In 1974 researchers at the Medical College of Virginia, funded by the National Institute of Health to find evidence that marijuana damages the immune system, found instead that THC slowed the growth of three kinds of cancer in mice — lung and breast cancer, and a virus-induced leukemia. The DEA quickly shut down the Virginia study and all further cannabis/tumor research. [URL removed by moderator] Oh lets not forget the US owns the patents for medical marijuana. Lets also keep in mind that marijuana is a natural plant not an illicit drug.

  33. Jerry

    yes, they must stop smoking before they get the disease. stop smoking now, try this easy method like Allen Carr method.

    • Chris

      Tobacco and marijuana are two very different things, and for most of the population, marijuana IS NOT an addictive substance.

      Allen Carr has wrote a book about quitting almost everything except marijuana, heck, he probably would of smoked some for the pain in the end if he hadn’t gotten lung cancer from a half a life of smoking tobacco.

  34. Willie

    Alarming and eye-opener excellent article.
    It is very important for teenagers and adults to know the consequences of using marijuana. There are still many side effects to discover but the ones we already know are shocking and not worth the risk at all.

    • Me

      No. I’m afraid that the fact that you blindly absorb this information like a sponge without any consideration of the legitimacy of the results of this research is what is truly alarming.

  35. Marianne

    If only more people were made aware of the dangers…there would be less traumatised families and young people being kept on lithium in asylums.

  36. shawn woodhull

    Every body around me smokes weed and most have attitude problems or just lazy.

  37. Monterey Bud

    The Nation’s Cancer Institute, NOT JOE ROGAN (for whom I like)for the very first time gives info on its website on cannabis and cannabinoids (the active medications within the cannabis plant). They report: “The possibility advantages of medicinal Cannabis for individuals coping with cancer include antiemetic effects, appetite stimulation, discomfort relief, and enhanced sleep. In the concept of integrative oncology, the healthcare provider may recommend medicinal Cannabis not just for symptom management but in addition for its likely direct antitumor effect.” The web site also states: “Cannabinoids possess a favorable drug safety profile. Unlike opioid receptors, cannabinoid receptors aren’t situated within the brainstem areas controlling respiration therefore, lethal overdoses because of respiratory system suppression don’t occur. Because cannabinoid receptors can be found in tissue through the body, not only within the nervous system, negative effects include tachycardia, hypotension, conjunctival injection, bronchodilation, muscle relaxation, and decreased intestinal motility. Although cannabinoids are thought by some to become addictive drugs, their addictive potential is substantially lower compared to other recommended agents or substances of abuse.” We now have discovered that the majority of our patients who’ve cancer find tremendous relief of nausea, better appetite, less weight reduction, less negative feelings, better sleep and overall low unwanted effects. It’s great to determine the NCI finally acknowledge the advantages of this natural medication to enhance the standard of existence for cancer patients. And don’t forget, there’s you don’t need to need to smoke the medication vapes, tinctures, along with other techniques to accept medication can easily be bought.

  38. tomi

    I wonder what the mindless furor of fear factor, joe rogan, would say if presented with this study. That numbskull is one of the biggest proponents of legalize marijuana this side of a rock.

  39. Monterey Bud

    As a point of fact I feel a need to mention that marijuana is by far one the least harmful substances being consumed today on a recreational basis as The most commonly used painkiller in the US is acetaminophen (brand name Tylenol). This is easily available over the counter. Acetaminophen is also in sleep aids (for instance, Tylenol-PM), and in strong prescription narcotic painkillers such as Vicodin and Percocet. Recent studies have found that acetaminophen is the leading cause of liver damage and probably is responsible for 1600 cases of acute liver failure that occur each year. The drug is thought to be safe at the recommended dose but because it is in so many different kinds of medication, people often end up taking double or even triple doses if they are using different painkillers or sleep aids. An FDA advisory panel urged the FDA to ban Percocet and Vicodin and other prescription drugs that contain acetaminophen. Due to the amount of money made by pharmaceutical companies by the sales of narcotic medications, and the fact they spend about $150 million per year lobbying our government officials, it will be a long time before any real changes take place.

    In 1998, the Journal of the American Medical Association published a study that stated that prescription medications were the fourth leading cause of death in America. Another study reported that there were 106,000 deaths per year from non-error, adverse effects of medications. And are you ready for the really scary part of this (as if that was not enough) – 2.2 million Americans per year are injured significantly by prescribed medications ending up with serious reactions and even with permanent disability. Not from accidental or intentional overdose, just from taking the prescribed dose.

    Here is another scary fact: more than half of the experts hired to advise our government on the safety and efficacy of prescription medications have a financial interest or relationship with the pharmaceutical companies that will benefit by their decisions. Can you guess what advice they will give when they own stock in a “wonder drug” that may have problems or require more testing before it is released?

    Here is some information from an article by Peter Breggin in Psychology Today in July 1994 (hope you are sitting down because this is almost unbelievable):

    “Contrary to widespread public belief, the FDA does not conduct any of the studies used for drug approval; they are financed, constructed, and supervised by drug companies using doctors they hire. While it may take a decade for a drug to get through the FDA bureaucracy, the actual controlled scientific studies last–as in the case of Prozac–just four to six weeks. Anecdotal material is collected on longer-term patients, but for Prozac, only 63 patients were followed for more than two years before the drug’s approval.

    For starters, seriously suicidal patients and hospitalized patients were excluded. Of the included patients, many were allowed to take sedatives and minor tranquilizers to overcome Prozac’s stimulant-like side effects, vastly compromising data interpretation.

    After weeding out the most badly flawed studies, the FDA found only four that were adequate enough to consider. One of these showed that Prozac was no better than placebo. Three others supposedly showed Prozac to be somewhat superior to the sugar pill, but not as good as older antidepressants. However, due to adverse drug effects and lack of drug effectiveness, the dropout rates in most of these studies was very high.

    While the gross number of patients receiving Prozac in all the trials was more than 5,000, the actual number finishing the trials used for approval was very small. When I counted the actual number of patients who completed the four- to six-week trials used for the approval of Prozac, it turned out to be a grand total of 286. It bears restating–only 286 patients finished the four- to six-week trials used to determine Prozac’s efficacy.

    Because of the high dropout rates and because Prozac was often no better than placebo in many trials, many statistical maneuvers were required to make the studies look positive. In one of the key studies, involving six different sites around the country, results at five sites showed Prozac to have no benefit. One site–representing 25 percent of the patients who finished the trials–was discarded. Then the data from the remaining sites were pooled. This is such a scientifically unacceptable practice that the FDA prohibits drug companies from doing it in the studies used to support advertising claims. Yet the FDA allowed it in this case. Otherwise Prozac could not have been approved.”

    Scary stuff. Still Prozac and other anti-depressants are prescribed like crazy, the pharmaceutical companies are rich, and people suffer.

    Does your doctor take the time to explain all of the side effects of newly prescribed medication? Most doctors these days don’t have the time to explain anything much less the lengthy list of toxic effects of medication. Remember too that most M.D.s have no training or experience in any alternative medical treatments and are reluctant to even discuss them with patients. So you get a prescription for what ails you and off you go.

    If you take any medications, you should research all of the side effects and think about the potential harm that can be done to you. Think about why you take the medication and think about alternative choices. Think about how the pharmaceutical companies make 11 billion dollars per year at the expense of Americans. Think about using medical marijuana if you are on painkillers, anti-depressants, anxiety medications, or sleeping pills.

    Marijuana has been around for more than 5000 years and is considered to have an excellent safety record. Between 1979 and 1998, there were 23 reported deaths due to cannabis, and when you look at the 23 people, they were all suffering from life-threatening illnesses (cancer, diabetes, etc) and were using marijuana medically. It is likely that they did not die from cannabis but from their illnesses. (Even if they died from cannabis, that is 23 deaths over 19 years, compared to more than 100,000 deaths per year from prescription medications!)

    Medical marijuana is natural medication, not synthetic. There is no organ damage and if taken with a vaporizer, eaten or used sublingually (under the tongue), there is no lung damage. It helps with so many conditions that patients who were taking multiple medications have been able to reduce the doses or eliminate the medications completely by using medical cannabis. Be smart and do your own research. Decide if you want to be one of the unfortunate statistics for 2009.

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  41. john allen

    Preliminary clinical trials show marijuana might be useful for pain, nausea and weight loss in cancer and HIV/AIDS and for muscle spasms in multiple sclerosis.

  42. John Mac

    I’m in college right now, and whenever someone asks me if i want a hit of weed, I just say, “naw man I pass on grass.” Great one-liner and can proudly say have never tried it and never will!

  43. Steve Carson

    I liked your blog about “teens who smoke pot at risk for later schizophrenia”

    If you would like to watch some free documentaries on
    schizophrenia go to http://www.documentaryconnection.com and just paste a keyword into the google custom search engine.

    Thanks

  44. Rena Graham

    well i think teens do drugs because they have so much stress in there life and they have nothing else to make it feel like they are doing something that helps there stress so they do drungs and they get addicted to it everytime they get stressed out.well that my opinion…..and there is alot more to be said from other people.

    One way to circumvent this is Very simple: Let the US government ratify the Framework Convention on Tobacco Control (FCTC) and you will see an improvement. Tobacco smoking and weed smoking are cross-cutting issues. It goes like this: Tobacco smoking to weed smoking and to drugs. The formative stage of weed and drugs is tobacco smoking.

    Cheers!
    Rena

    • Chris

      Similar issues? Let’s see.

      Tobacco use causes 6 million deaths a year, a third of those deaths from cancer, according to a report released by the American Cancer Society and World Lung Foundation. These same groups have not one study on marijuana deaths because there are none.

      For you to say tobacco and marijuana are a “crisscrossing” issue is ridiculous and unintelligent.

  45. BillyBob

    Please take out the line “such as believing the television is transmitting secret messages” and sub in something less specific. A teen reading that is going to laugh and discount everything this article says.

    • Jajisee

      So much uninformed comment in this thread. My son smoked pot for ten years. His “love-of-his-life” left after realizing pot was more important to him than she. A year later he had the first of four psychotic breaks. He stands six inches from tv and “listens” to the messages it’s sending. Among other severe symptoms of his diagnosed schizophrenia. There is also a possible genetic link. Don’t discount what you don’t know about. It’s a horrible condition that affects a whopping one percent of the population. 3,100,000 Americans. 80% of the homeless are schizophrenic. It doesn’t go away. The sad result of a decade of MJ in our family is the destruction of multiple lives.

  46. AbuBakar

    Well parents need to really look after therir children, where they go what they do, how are their friends. Because these are the factors which are sometimes ignored by parents because they dont have time to do this, hence this carelessness of parents result in children being addict of drugs, doing bad deed and more. Along with mentioned factors dental health is also affected.
    [URL removed by moderator]

  47. Kendra Willis

    This is scary and definitely an eye-opener for parents. Whether all of this information is accurate or not, it is not a surprise for us to know that everything in excess will always have a negative result, this includes the use of marijuana or any drug for that matter. We wouldn’t have this sort of problem in the first place if we made sure that we educate our kids with the effects of these types of drugs and if we’re involved with their lives as they’re growing up. Educating ourselves in finding out if our kids are at-risk of drug use will aid in providing them immediate help. This questionnaire for at-risk youth might help.
    http://www.atriskyouthprograms.com/teen-questionnaire.html

  48. Mel

    whilst these are all interesting studies….have you looked at the wider population of Netherlands (which Cannabis use is completely legal) and the percentage of those who developed psychosis?????

  49. Matt

    Slightly misleading, the powerful strains of marijuana may increase schizophrenia, normal marijuana that has balanced THC will not.

    Matt

    • Chris

      Saying stronger strains of marijuana may cause increased risks of developing schizophrenia and “normal” strains will not is as unintelligent as saying marijuana may cause increased risks of developing schizophrenia. Where you get your info I have no idea.

  50. steven clark

    Parents has got many responsibilities until the kid reaches 18 or 20. Because parents are basically their first ideal. they do the same thing what their parents are doing. Very well explained article.

    [URL removed by moderator]

  51. aliving

    fiona-If winter comes, can spring be far behind ?

  52. fish oil and psychosis

    There’s a current study that fish oil rich with omega3 can help prevent psychosis. But this doesn’t mean that we can allow weed to be puff just because you have a food supplement that is rich with omega3.

  53. Aaron

    It’s good that everyone here is at least is curious enough to look at this article. I STRONGLY encourage anyone to watch this (relatively) unbiased PBS documentary about the SCIENCE of marijuana.

    http://watch.montanapbs.org/video/1825223761/

  54. runerev@gmail.com

    Anyone drinking or smoking at early age WILL have some effects in their psyche.
    A little off subject I witnessed a 14 yearl old many years ago doing Extacy and he looked like a drugged zombie. If this would have been on a mature adult, through with the growth cycle the looks on his face would be diffeerent. This is my opinion because I have been there myself. No I did not use extacy at the age of 14. When it comes to “drugs” you have to be careful ANYHOW. Depending on the drug and your psyche it can affect a lot of things like anxiety for instance. This is not something new though. It is just another article proving that it should be under some control. I am for legalisation of Cannabis but I believe we should have some control over like an age group over 18 is allowed. When I was that age I had been smoking for 1 1/2 years but I did not know much about it. More information on the subject is what we need. In our brain we have endo-cannabinoids which is the receptor for Cannabis. Strangely enough been there for a long time!!!
    We are built for it. All we need is more CORRECT information NOT from politicians.

    What we NEED to remember is:
    ABUSE and USE is NOT the same thing.

    [URL removed by moderator]

  55. thestats

    I agree the effects on the growing brain are sometimes not reparable,
    [URL removed by moderator]

  56. thestats

    Parents need to be responsible – teens should also be brought up very early on to know the dangers of drugs/addiction, its a very nicely done article,Thanks. site

  57. Ray C

    I agree with Nick. Parents definitely need to be more responsible,

  58. Nick Jones

    I dont think some teens realise the effects of drugs, especially alcohol since it’s so easily available.

    It’s the parents that are at fault in my opinion.

  59. Anonymous

    Saying thanks definitely will not just be enough, for the fantastic clarity in your writing. I will certainly at once grab your rss feed to stay abreast of any updates. Genuine work and much success in your business dealings!

  60. Susanne Vickers

    I have a young daughter, aged 17, who has been smoking marijuana for nearly two years (that I’m aware of). I have seen a remarkable shift in her personality disposition, especially over the last 5 months. With all of her hormonal fluctuations taking place at this crucial time of her life it is no surprise that I am worried she is digging herself into a hole by using marijuana on the side.

    I’ve told her many times that I am not against her smoking, that is up to her, but I have told her that I wish she just wait til she is over 21 to do it. I think then she will have some more awareness of herself and the personal insights this can bring may allow her to see how she can use marijuana in a more constructive manner.

    At the moment she is smoking excessively.

    Seriously, it scares me.

    Thank god she has not had any psychosis episodes, however she has a friend who just had one. What scares me even more is this has not deterred her. Why?…

    Someone above mentioned that marijuana is a ‘self medicating’ behavior… I couldn’t agree more. I feel this is the reason that she feels such a connection with marijuana. It allows her to escape the current pressures with school, social pressures, social expectations, relationships, etc.

    I can’t blame her…I mean, don’t we all need an escape in our lives too.

    I feel as if there is a well of imbalance beneath all drug-use. Unfortunately there is a lot of activity in majority of our country that is viewed as normal but in which it acts just like marijuana to self medicate… whether it is television, eating junk food, sex, internet, etc. I feel that the need to self-medicate is so wide spread that it is difficult to know exactly where to start to be able to solve it.

    Maybe that is the problem in the first place. We do not see that marijuana use is not THE problem per se, but in fact marijuana use is just a ‘symptom’ of a deeper problem.

    In this light the question may not be ‘how do we solve the problem of marijuana’ but ‘how can we DISSOLVE the underlying psychological and emotional blocks that are attributing to marijuana use’.

    Its not going to be easy. For example, I caught my daughter (unintentionally) looking at a website [URL removed by moderator] which explains how she can grow her own marijuana in her wardrobe or a small room. This sort of website is available to anyone at anytime by the click of a button via google… for free.

    This is the challenge we face.

    So the questions I pose are:

    1. What are the underlying issues that are causing a child to self-medicate?

    2. What are they trying to move away from and what are they trying to gain by using marijuana.

    3. What positive alternatives can the child use to obtain the same effects they are having by using the marijuana?

    Number 3 is a big one. Without a more empowering alternative they will just trade one addiction for another.

    I look forward to hearing your responses.

    Susanne Vickers

  61. Jones Spores

    “the expected rise in diagnoses of schizophrenia and psychoses did not occur over a 10 year period,” authors concluded. “This study does not therefore support the specific causal link between cannabis use and incidence of psychotic disorders. … This concurs with other reports indicating that increases in population cannabis use have not been followed by increases in psychotic incidence.”
    [URL removed by moderator]

  62. Caroline

    One thing that is conspicuously omitted from Dr. Matthew Large’s February 7, 2011 report is how “psychotic” symptoms were defined and the severity level of those symptoms. I suspect that the studies that Dr. Large collected for his meta-analysis narrowly define “psychotic” symptoms, which may explain why his statistics surprisingly showed no significant association between “psychotic” symptoms and alcohol use. Moreover, this report does not appear to consider the real possibility that the “onset of psychotic symptoms” are being confused with the common side effects of marijuana. Many persons that do not develop schizophrenia or other mental illness still experience occasional paranoia or anxiety during the course of their marijuana use due to regular/heavy use or high potency product. Considering this, it makes sense that you will have both schizophrenic and mentally healthy persons reporting “psychotic” symptoms at a significantly earlier age compared to those persons that have never used marijuana or any other drug.

    Of course there may be other confounding factors, many street dealers distribute marijuana along with other drugs. Studies show that the younger people are when they first try marijuana, the more likely they are to be introduced to other illicit drugs, including those that could cause more severe psychotic side effects. On the other hand, you also have children using Ritalin and other prescribed stimulant drugs that increase dopamine levels, in order to improve academic performance. It is a growing concern that these substances may contribute to schizophrenia.

    Tobacco use may also be another confounding factor. According to the following U.S. National Institute of Mental Health website:

    “It is hard for people to quit smoking because it might make their schizophrenia symptoms worse for a while.”

    http://www.nimh.nih.gov/health/publications/schizophrenia-easy-to-read/schizophrenia-easy-to-read.shtml

    According to Dr. Large’s report: “No study [that he collected] included tobacco use in its definition of substance use.” It is common for marijuana users to also smoke cigarettes, so nicotine withdrawal symptoms may be mistakenly attributed to marijuana use. Many former marijuana users struggle with nicotine addiction long after they quit using marijuana. However, marijuana withdrawal symptoms can also be stressful for heavy, frequent users (though not near as severe as nicotine), so that may be coming into play. However, scientific studies show that marijuana is significantly less addictive and intoxicating than alcohol, and much less addictive than nicotine. http://www.drugwarfacts.org/cms/node/28

    Regardless of whether or not marijuana, alcohol, or tobacco are significant contributors to schizophrenia, children at such a young age should not be using any of these substances. There definitely needs to be a stronger debate over whether regulation of marijuana in a manner similar to alcohol could be helpful in impeding regular use among young teens.

    According to survey data from Monitoring the Future, two to three times more American students in the 8th and 10th grades use marijuana on a daily basis than alcohol. This ratio increases when daily marijuana use is compared to daily drunkenness.

    http://www.monitoringthefuture.org/data/10data/pr10t4.pdf

  63. Rob Mellor

    i am not against cannabis smoking, but i don’t endorse it also. and i believe in every person’s free will to do whatever they please, just as long as they don’t harm anyone or bother anyone. if they like to smoke pot, we should educate them about the effects, but let them choose to continue. then, we could also advise them to do it in private. thats just my 2 cents.

  64. I agree with a lot of what you’re saying here but it could do with more detail. If at first you dont succeed, try again. Then quit. Theres no use being a damn fool about it.

  65. Miguel Bojorquez

    I’ve read quite a bit on this subject and am curious for any insight. I am 18 years old, and had smoked marijuana habitually for a period of three or four months. After time, I started noticing what I later found to be symptoms of schizophrenia.. Altered and diluted long-term memory, maddening inner dialogue and periods where I lacked emotion. After all of this, I began to put two and two together and did research on the subject, and found it to be marijuana related schizophrenia. I quit after this, but am worried that my drug use will lead to schizophrenia later in life.. Which frankly.. Is the scariest thing I could imagine. I pray to god that I don’t, but if there is a correlation, I would have loved to have known before hand. I can only hope that this research progresses, so that other teens like me won’t have to face the fear, doubt and depression of all of this.

  66. Lisa Lane Brown

    This is so sad. It stands to reason that there are long term effects to drug abuse. As a sport mental toughness coach[URL removed by moderator], I know how hard it can be to make a real change, once you are in the pattern.

    It will be interesting to see what other affects will be discovered as a result of long term drug abuse.

    It is also interesting to know what percentage of people know about psychosis and Schizophrenia that runs in their family. Sometimes these things are hidden through the generations.

  67. Donna

    We need studies that can differentiate between correlation and causation. Just because the sun rises every time you wake up, doesn’t mean your awakening causes the sun to rise. I wonder if we are simply dealing with troubled youth who are more likely to use marijuana.

    In February, psychiatric researchers at the University of New South Wales also held a press conference with the Australian National Cannabis Prevention and Information Centre trying to tie marijuana to causing or hastening schizophrenia illness.

    Serge Sevy, MD, Feinstein Institute for Medical Research, and other researchers concluded the following in response to Dr. Matthew Large’s February study:

    “As we believe that the data on the causal relationship between cannabis use and early onset of psychosis is still unconfirmed, it seems premature to suggest that intervention in one variable may result in change in another variable.”

    Darryl J Wade, PhD Department of Psychiatry, University of Melbourne, also expressed his doubts about the results.

    You can read the complete critiques at the following link:

    http://archpsyc.ama-assn.org/cgi/eletters/archgenpsychiatry.2011.5v1#14185

    With several recent media campaigns by researchers in the mental health industry, I wonder if their deliberate use of scare tactics linking marijuana as a cause of schizophrenia is a ploy to obtain more government funding to address youth mental health issues. Similar to what the DEA is doing in lobbying to label drug cartels as terrorist organizations, so they can get a piece of the homeland security pie.

  68. Peter - Substance Abuse Specialist

    Education is the key here I think. Parents need to remove their blinkers and prepare their children for the real world by discussing things like drugs and alcohol. A good source of information is http://www.drug-aware.com there is a good section on the signs and symptoms to look out for if you suspect somebody is using drugs.

  69. Peter - Substance Abuse Specialist

    The more research that is done the better surely? However, I find that people who use marijuana regularly are loath to admit that there is a problem (indeed many still persist with the myth that it is good for you!). Because marijuana is illegal, the people who first introduce it to younger people are not likely to point out the bad bits about it, so the younger people take on that persons attitude.

  70. Mark

    A friend of mine who has started smoking pot during his teen years has developed Schizophrenia when he hit 19. It is heart breaking for him and his family, and he has now to live on drugs (with huge side effects) for a long period of time. I don’t know if this is related to pot. Maybe some people are more vulnerable than others.. I know many other folks who smoked a load of pot but that are fine.. i guess time will tell.

    Mark J

  71. Melodee D. Lewis

    This conclusion is wrong… People such as myself are mentally ill from birth..We are psychotic anyway.. we are schizo anyway.. Marijuana sooths us. Creates a more rational person..Following the status quo in your research is biased and plain wrong

  72. Ann MacDonald

    Just read this interesting follow-up commentary from Dr. Ken Duckworth, medical director at the National Alliance on Mental Illness. Thought readers would be interested:

    http://blog.nami.org/2011/03/marijuana-and-risk-of-schizophrenia.html

    Duckworth cites a study which found that “users before age 15 were 4.5 times more likely to develop schizophrenia than nonsmokers, and those who delayed until age 18 had a risk of 1.6. This strongly suggests that, in addition to abstinence, delaying experimentation results in reduced risk.”

    Ann MacDonald
    Editor, Harvard Mental Health Letter

  73. Louise Weiss

    Why are so many of your posters semi-literate? Yes, I’ve adjusted for bad typing. What’s left is shocking.

  74. Donna

    Increased cannabis use by the public has not been followed by a proportional rise in diagnoses of schizophrenia or psychosis, according to the findings of a study published September 2009 in the journal Schizophrenia Research.

    Investigators at the Keele University Medical School in Britain compared trends in marijuana use and incidences of schizophrenia in the United Kingdom from 1996 to 2005. Researchers reported that the “incidence and prevalence of schizophrenia and psychoses were either stable or declining” during this period, even though the use of cannabis among the general population was rising.

    “[T]he expected rise in diagnoses of schizophrenia and psychoses did not occur over a 10 year period,” authors concluded. “This study does not therefore support the specific causal link between cannabis use and incidence of psychotic disorders. … This concurs with other reports indicating that increases in population cannabis use have not been followed by increases in psychotic incidence.”

    http://www.ncbi.nlm.nih.gov/pubmed/19560900

    The results of a separate clinical trial, published in October 2009, reported that the recreational use of cannabis does not stimulate the production of dopamine in a manner that is consistent with the development of schizophrenia.

    http://www.ncbi.nlm.nih.gov/pubmed/19539765

    • Chris

      Thank you, at least one open-minded intelligent person here.

      A similar study showed that cases of schizophrenia decreased in the early 70s just as marijuana use exploded, and another study showed how schizophrenia cases increased just after marijuana use decreased in the late 80s into the early 90s. Being these studies mean little, it shows that the anti-marijuana studies even mean less.

      Maybe these scientists and doctors at Harvard should explore the dangers of the “energy drinks,” a real and current epidemic in bad health.

      Note to all: Marijuana use skyrockets among teens currently. But you know one substance that’s always been used the heaviest, is the most deadly and is one of the only “legal” drugs available, alcohol. Go attack that.

  75. autoseedsbank..

    More Research needs to be done on this subject, the more i study it, the more i feel Cannabis is getting more phycoactive and is is having an adverse affect on developing parts of the memory. This must be having a long term effect.

  76. Donna

    “If you read the studies I cite – and you can do so by following the links – you’ll see the researchers actually controlled for the possibility of self medication. ”

    No, they did not. In fact, they specifically note the significant limitations of their study. There are plenty of actual reasons to keep young kids from using alcohol, marijuana and other substances – we do not have to invent them.

  77. Donna

    Here’s an excerpt from a study published in Schizophrenia Research I was referring to in my previous post:

    “the expected rise in diagnoses of schizophrenia and psychoses did not occur over a 10 year period,” authors concluded. “This study does not therefore support the specific causal link between cannabis use and incidence of psychotic disorders. … This concurs with other reports indicating that increases in population cannabis use have not been followed by increases in psychotic incidence.”

    Abstract: http://www.ncbi.nlm.nih.gov/pubmed/19560900

    Full Report: http://www.ukcia.org/research/keele_study/Assessing-the-impact-of-cannabis-use-on-trend-in-diagnosed-schizophrenia.pdf

  78. Amanda

    Correlation does not imply causality.

    It seems must more likely those with a genetic predisposition for psychosis are simply self medicating, which is an avenue this blog conveniently ignores.

    I was on the same page as Christy in regard to the inherent focus on this “refer madness.” The authors assumptions – based on the limited research – are akin to the melodrama of said industrial age film.

    • Ann MacDonald
      Ann MacDonald

      Amanda, I agree with you in one respect: correlation does not imply cause. Or – as I put it in my post:

      “So far, this research shows only an association between smoking pot and developing psychosis or schizophrenia later on. That’s not the same thing as saying that marijuana causes psychosis.”

      If you read the studies I cite – and you can do so by following the links – you’ll see the researchers actually controlled for the possibility of self medication.

      But you know – you and Christy are raising points that I raised with my editorial board months ago, when we did another story on this issue. For a long time “genetic predisposition” was presumed to explain why kids who smoked pot might develop psychosis later on. And it’s true – they are more at risk. But even young people with no family history of schizophrenia risk developing psychosis later on. Maybe that’s a risk some are willing to take. But — as someone who has seen the damage psychosis does to the brain — that is not a risk I’d want my niece or nephew to take.

      As for Reefer Madness, I’ve provided a link for readers who may not be familiar with this cult film.

  79. Christy

    Donna said: “None of the data can explain why rates of schizophrenia have remained stable or even declined since the 1950s, while marijuana use has increased exponentially. Unlike rates of cigarette smoking and lung cancer, which rise in tandem, marijuana smoking rates in the population do not correlate with higher rates of schizophrenia.”

    Well that pretty much settles the case. Will these researchers also focus on alcohol-induced psychosis or are they just interested in “reefer madness”? Drunks beating up on their spouses and kids; walking on the ledges of tall buildings; starting riots after sports games and raping women. If you want to stop insanity that would be a good place to start. BTW, next month is Alcohol Awareness Month.

  80. Brittany

    People are so worried about legalizing marijuana that they do not often look into the actual effects. People are too focused on the way marijuana makes them feel when they use it to understand the negative side of it. I wonder if people knew these assumptions if they would still use marijuana. I believe that some people just do not care. More and more people young and old are using marijuana more than ever. The high school I graduated from in 2009 was full of marijuana.
    I myself have never used marijuana in any way. It has been and always will be my personal choice to say no. This article helps make my decision easier, but no matter what was said about marijuana, I would say no.
    I believe that the negative effects of marijuana need to be more widely explained. The possibility of increasing a persons chances of developing psychosis or schizophrenia should be enough to make people turn away. Those two things are life changing circumstances. Even if it is not completely confirmed yet, it is a possibility.

  81. Donna

    Ann McDonald wrote: “This is how research works. Years ago, scientists first noted an association between cigarette smoking and lung cancer. Only later were they able to figure out exactly how cigarette smoke damaged the lungs and other parts of the body, causing cancer and other diseases.”

    None of the data can explain why rates of schizophrenia have remained stable or even declined since the 1950s, while marijuana use has increased exponentially. Unlike rates of cigarette smoking and lung cancer, which rise in tandem, marijuana smoking rates in the population do not correlate with higher rates of schizophrenia.

    Moreover, it’s disturbing that the researchers provided no breakdown of what symptoms they consider “psychosis” nor do they indicate the severity of these symptoms. Yes, overusing marijuana can cause paranoia in some people, but this isn’t anymore news than a study saying that alcohol fosters violent and reckless personalities along with a sense of invulnerability. As far as the association between marijuana and schizophrenia, it’s odd that Australian researchers in their meta-analysis of previous studies deliberately refused to factor tobacco use (which is quite common among schizophrenia patients) because that might have provided clues as to whether the association between marijuana and schizophrenia is causative or correlative. If you are going to go through all that trouble in studying the association of various substances and other factors, why not include tobacco use in the analysis? This demonstrates significant bias in the research.

    Finally, mental illness does not develop overnight rather it’s a very gradual and subtle process. There is absolutely no way for current science can determine whether this process began before or after an individual’s marijuana use, and the researchers did caution about the limitations of self-reported data.

  82. linda

    My son, heavy marijuana user since about 13 is now 19 just experienced first psychotic episode. I tried without success to warn about pot use just for the effect on lungs and learning but all efforts failed. There were no symptoms to self-medicate and no family history. Son is risk taker and oppositional, more of a substance abuse personality. Now son is mentally ill, perhaps for life. I’m not saying that pot was the cause, but it is an unnecessary risk. So what is the reason for any teenagers to use pot? Many adults excuse or even promote pot and even are in denial about this mounting evidence. See the video “The Downside of High” for a very credible scientific perspective.

  83. Lance Hall

    PS I also agree with your real life application conclusion: the association between the two is a significantly strong reason to caution teens (and anyone up to 25 at least) about marijuana use. The fact that it might be a pot use caused association of double likelihood for such tragic outcomes is certainly reason for caution if not down right scary, when one considers the rate of increase of marijuana use among America’s teens and young adults.

  84. Lance Hall

    This is certainly an interesting subject. The writing community is more quickly able to respond to the interest by the populous, than is the research community. While I’m sure you put some time into writing this article, I’m also pretty sure it did not take 10-15 years, the way a good study on the topic does. I appreciate, more than I can say, the fact that you are responsible in these regards, by reminding the reader (who may not deal with interpreting research on a daily basis) that the studies thus far indicate only an association between marijuana use at an early age and psychosis. Unfortunately, even most scientists (let alone non-scientists) I have read on the subject don’t do this. Of course, as a rational guy who is a little perfectionistic about logic, I must note that from the title to the end of your article, you seem to treat this lack of evidence as an annoying technicality. You assume all the theories on the pot-use-being-the-cause side are right and will be proven so with time. You don’t even mention any of the theories about how those teens could have responded to developing psychosis with the pot use. Such theories are equally supported by all the research you mention in this article.
    Like I said though, I am being a perfectionist. Your article is the least biased and most scientifically accurate that I have seen outside of scientific journals (I.e in anything that the public will actually read.), and I appreciate it. =)

  85. Andrew

    This article is completely un-factual, there is no evidence pointing to why there may be a link between psychosis and cannabis consumption. Anyway, there was one study that showed that those who sustain long term use of cannabis from adolescence to adulthood AND HAVE A GENETIC PRE-DISPOSITION, for schizophrenia, may be exasperated. And although there is strong evidence that refutes this, shouldn’t we be asking our selfs why dont we legalize this plant and restrict it to those 21 and over like alcohol. I would like to know why these soldiers, from smoking more than 50 times, are more likely to have mental complications later in life. Judging by the Heath Tulane study of 1974, commissioned by the United States Government, which was the basis for saying pot kills brain cells, this study was performed by suffocating the monkeys, with smoke and gas masks, to kill brain cells. I am not sure of all of these Harvard “editors” have it right, i am a neuro biologist and have been studying psychoactive substances impact on the brain since 1999. I have seen no link between THC and any forms of psychosis.

    • Ann MacDonald
      Ann MacDonald

      Dear Andrew,

      Thank you for writing.

      I think you should reread the post, and perhaps the papers to back up what I say, however. It’s true that for a long time, researchers thought that only people with a genetic predisposition to schizophrenia might be more vulnerable to the effects of cannabis. New research — including the study that we cite — has been designed more carefully to control for that possibility. The researchers excluded young people who had already smoked pot or had experienced psychosis before the study began so that they could evaluate the impact of smoking pot on people who had never experienced psychosis.

      I urge you to reread the post and obtain the papers (the commentary is freely available online).

      As for your policy comments, that is beyond my expertise.

      Best wishes,

    • anonymous

      All of this feels contrived. Considering the “share” that Harvard holds in the pharmaceutical industry, of course they’re biased. Just look at how much money the Rx industry loses to medicinal marijuana, and could lose, if it were legal. Take some time to really look into the pharmaceutical industry, and see for yourself whats going on with it, and its constituents.( They have connections to other gentlemen with stock in lumber too…)
      Marijuana *causing* an incurable mental disorder is an arrogant assumption indeed. According to my research, the causality of schizophrenia in relation to marijuana use is quite the reverse of the indication, and to add to that marijuana is frequently prescribed to patients with a gamut of mental disorders, including schizophrenia, and have had great success in treating those individuals. Not to mention that as the average number of Americans smoking marijuana in the us rose exponentially, so too has the number and duration of schizophrenia cases decreased in the last decade. On another note, the slight decrease in volume in the frontal lobe(mostly), relative to psychosis has shown damage to preexist psychotic manifestation. Not so with schizophrenia, but neither has any conclusive research that I’ve seen shown evidence in either direction for it,but i digress. The point is
      this article cites no legitimate evidence to what is being theorized from the hazy statistics, and ancient studies she provides, thus making it rather vague and uninformed.

    • anonymous

      The cortex volume discrepancy is in reference to a later post, to be clear.

  86. Deplorable

    I see the association as an attempt for these young people to self medicate. Obviously something is wrong, and they know it.

  87. Daniela C.

    This is an excellent article! Alarming and eye-opener.
    It is very important for teenagers and adults to know the consequences of using marijuana. There are still many side effects to discover but the ones we already know are shocking and not worth the risk at all.
    Thanks for sharing and hopefully many people get to read this great research.

    Daniela C.

  88. autoseedsbank..

    I agree i think the dangers of smoking cannabis at a young age have not been totally explored yet.