There’s Been Over 20,000 Studies On Marijuana; What Is It That Scientists ‘Do Not Yet Know?’

US News & World Report recently probed the subject of cannabis science, publishing a pair of stories on the subject here and here.

Neither story particularly breaks any new ground, though the author (who I spoke with extensively prior to the stories publication) does note that investigators are now assessing the use of cannabis for a wide range of disease conditions, including Alzheimer’s disease and the so-called ‘superbug’ MRSA (multi-drug resistant bacterial infections).

Quoted in the story is Columbia University researcher Margaret Haney. I’ve written about Haney’s clinical work with cannabis before. In particular, Haney was the lead author of a 2007 clinical trial concluding that inhaled cannabis increased daily caloric intake and body weight in HIV-positive patients in a manner that was far superior to the effects of oral THC (Marinol aka Dronabinol). The study further reported that subjects’ use of marijuana was well tolerated, and did not impair their cognitive performance.

Yet Haney’s comments in US News and World Report ring tepid at best.

“I am not anti-marijuana, I’m not pro-marijuana. I want to understand it.” Haney expresses frustration at what she considers wrongheaded efforts by states to legalize medical marijuana. There is too much, she says, that scientists do not know.

Haney’s refrain is a common one, and at first glance it appears to make sense. After all, who among us doesn’t want to better understand the interactions between the marijuana plant and the human body? Yet placed in proper context this sentiment appears to be little more than a red herring. Here’s why.

Marijuana is already the most studied plant on Earth, and is arguably one of the most investigated therapeutically active substances known to man. To date, there are now over 20,000 published studies or reviews in the scientific literature pertaining to marijuana and its active compounds. That total includes over 2,700 separate papers published on cannabis in 2009 and another 900 published just this year alone (according to a key word search on the search engine PubMed).

And what have we learned from these 20,000+ studies? Not surprisingly, quite a lot. For starters, we know that cannabis and its active constituents are uniquely safe and effective as therapeutic compounds. Unlike most prescription or over-the-counter medications, cannabinoids are virtually non-toxic to health cells or organs, and they are incapable of causing the user to experience a fatal overdose. Unlike opiates, cannabinoids do not depress the central nervous system, and as a result they possess a virtually unparalleled safety profile. In fact, a 2008 meta-analysis published in the Journal of the Canadian Medical Association (CMAJ) reported that cannabis-based drugs were associated with virtually no serious adverse side effects in over 30 years of investigative use.

We also know that the cannabis plant contains in excess of 60 active compounds that likely possess distinctive therapeutic properties. These include THC, THCV, CBD, THCA, CBC, and CBG, among others. In fact, a recent review by Raphael Mechoulam and colleagues identifies nearly 30 separate therapeutic effects — including anti-cancer properties, anti-diabetic properties, neuroprotection, and anti-stroke properties — in cannabinoids other than THC. Most recently, a review by researchers in Germany reported that since 2005 there have been 37 controlled studies assessing the safety and efficacy of cannabinoids, involved a total of 2,563 subjects. By contrast, most FDA-approved drugs go through far fewer trials involving far fewer subjects.

Finally, we know that Western civilization has been using cannabis as a therapeutic agent or recreational intoxicant for thousands of years with relatively few adverse consequences — either to the individual user or to society. In fact, no less than the World Health Organization commissioned a team of experts to compare the health and societal consequences of marijuana use compared to other drugs, including alcohol, nicotine, and opiates. After quantifying the harms associated with both drugs, the researchers concluded: “Overall, most of these risks (associated with marijuana) are small to moderate in size. In aggregate they are unlikely to produce public health problems comparable in scale to those currently produced by alcohol and tobacco. On existing patterns of use, cannabis poses a much less serious public health problem than is currently posed by alcohol and tobacco in Western societies.

That, in a nutshell, is what we ‘know’ about cannabis. I’d say that it’s ample enough information to, at the very least, cease the practice arresting people who possess it.  As for what else Dr. Haney and others of a similar mindset would still like to know — and how many additional studies would it take to provide them with that information — well, that’s anybody’s guess.

125 thoughts

  1. Study=stall and forget. If marijuana created as much violence and aggression as alcohol it would have been welcomed with open arms by this so called govt that is in place now. Who will fight there wars with no aggression. Get it. Remember Kent State?

  2. In a dream as real as life itself i dreamt a time years ago ( today ) when Marijuana was illegal and during this time all thought back to when Marijuana was illegal & the people were stunned to think of the ignorance of the rulers of the Earth during this time . How stupid we were to punish people for using this God given herb which brought so much good to today’s current World .

  3. NORML ,
    While cleaning up my documents i came across this letter that sent to , UNITED CHURCH of GOD Dated 2/27/10

    Although I am grateful for every publication you are good enough to send me and of which I thoroughly read i am also in complete dissagreement to some of your views concerning marijuana a God given herb put on earth by God . I encourage you to read about the herb bearing seed God put on earth . Please go to ; Genesis 1;29 – 31 and read Genisis 1 ; 12

    Some of your articles tell us marijuana is the
    “ Devils drug “ but I find only good things written about God bearing seed in the Bible and not so good things written by the hypocrites who comment negatively in your publications regarding marijuana .

    These people who mention bad things about marijuana surely are the Devil themselves . Please read ; Romans 14;17 – Ephesians 5;18 and Galatians 5;19 – 21 . Mentioned are many many times against drunks and drunkeness in the Bible . Surely the author(s)of these articles have drank alcoholic beverages or taken prescription medications that can cause addiction , death , spousal abuse , divorce , aggression , violence and murder and irreversible health problems . Yet ,marijuana , a gift from God does none of these things .

    God has made a gift & has given it to mankind . Man refuses God’s gift and so he makes man made drugs ( alcohol is an example ) that often kills and cause destruction . Surely , I know the Bible better than those who only pretend to be Christians who hide behind a white shirt & tie . In those days , Jesus will say “ depart from me for I knew you not “.

    In conclusion………….please continue sending your magazines to my P.O. box.
    Please find my gift of $ xxx enclosed .

    God Bless ,

    ( name with held )

  4. @ Dave #42 – Dave, you must not have read the numerous articles that clearly show that smoking marijuana does not damage DNA! That’s just what they want you to believe. It actually improves it! LOL!


    Oh, I forgot, there’s no more hero politicians like this to be found these days.

  6. If our government doesn’t care about arresting and imprisoning people for marijuana,destroying families and
    having to lie to keep marijuana illegal,they sure don’t care about another countries dead.

    “The 40-year jihad launched by Richard Nixon in 1970 was supposed to eliminate the scourge of street drugs and protect America’s youth. Street drugs, however, remain readily available to any determined 16-year-old seeking a joint or damn near any other drug du jour.”

  7. John Dougherty

    Democratic candidate for U.S. Senate, Arizona
    Posted: July 4, 2010 12:58 PM

  8. i know this is late to post a reply on this,but here goes
    please oooh please look at dr ron paul. i just think we should all go to dc and light up each and every day.
    no permits just Americans expressing to obummer,
    “my body period you have no say ” if you be leave ether dems or repubs will do this you are wrong. they don’t want it legal. but umm is this not our government? i guess not. if we could get a group of 50 every day. perhaps the whole of America would wake up.people MY (our)Constitution secured our rights governments try to take the away.i say we stand together and say no to big bro BO. what can he do if there are arrests then court. ever heard of jury nullification?

  9. 5.”VERY good article. The war on marijuana has proven to be one of the BIGGEST governmental mistakes in history. The government doesn’t want to admit it made a mistake. Thats why its taken decades longer for the PEOPLE to gain any sort headway in comparison to the Prohibition days.”

    I’m not personally attacking you Bryan, but it was NOT a mistake at all, neither is the continuation of this agenda. There ARE government individuals who would repeal it if they could, but as a majority they don’t want their conservative puppies to sway the other way. The government deliberately misinformed the public. It’s only through the individuals from here and the many other organizations that pushed for FACTUAL information and freedom of personal life choices that the misinformed have been able to see the propaganda.

    As for the individuals who are ignorant of SCIENCE and accepting of the government lies, I hope you rot extra fast.

  10. California is on the verge of change this year.The economy will dictate the change .The fact that pot helps cancer patients and vomiting should be enough.What moron thinks that Pot should not be legal and canada should be takin to the BANK from KONA is nuts!~Tell Your congressman , it is time to reclassify now!

  11. Thank you for that link, cg. It definitely explains a lot, spelling things out pretty blatantly… which is a good thing. The cartel money laundering is outrageous! That has really gone on?! It really is just like the 1920’s again. Only this time the mobsters are in a neighboring country, which allows them some breadth from law enforcement here in the states. This cannot continue. Change is coming, one way or the other, because this behavior is not sustainable.

    Something must give: the water will have to divert or the stone will have to roll.

  12. More research needed? Absolutely! Do we know enough to grant legal access to suffering patients? Absolutely! With evidence of the relative safety of cannabis, it is simply cruel and immoral to deny medicine to anyone who could benefit.

    The most stunning fact is the number of organizations refusing to allow research (NIDA, FDA, DEA, The Feds). If they truly believe cannabis is dangerous, the best way to prove it is to conduct credible research.

    That, in itself, should tell us they fear the outcome of such research.

    Just as Dr. Donald Tashkin expected to reveal cannabis to be more dangerous than tobacco, then wound up recommending its decriminalization, the NIDA isn’t about to allow someone to go further in proving their “abused drug” has actual medical benefits and should be rescheduled. That’s not in their job description.

    We know the truth about cannabis. The feds, Big Pharma, and everybody else standing in the way knows the truth! They’re simply banking on the ignorance of Americans to maintain the status quo.

    And so far, they’re succeeding.

  13. Excellent article, I do have to agree with everything here in that the medical use of marijuana should be legalized I of course would like to see the Recreational use of the drug legalized as well but can wait! i believe that we will see the reform of laws prohibiting the use of this wonderfully plant, and we will also see many new technologies surface as far as harvesting, and use of the plant for its environmentally friendly byproducts!

  14. No cognitive impact, really?

    There are plenty of studies to the contrary.

    Probably the biggest thing we need to figure out is (a) how this could impact motor vehicle operators and (b) how to measure the level of “intoxication” by users when they are operating a vehicle.

    If our states can figure out (a) how to meausre the level of “highness”, (b) how to establish a baseline against which to measure that level (ie, something similar to a breathalyzer), and figure that out in a way that is affordable so that every single police car can be equipped with such a measuring device, and ensure that the device does not violate anyone’s privacy rights, THEN I have no problem with marijuana.

    Public safety is still important, folks.

    [Editor’s note: Not sure citing a study from such a bias anti-cannabis government agency borne from prohibition is a credible scientific source…even the name of the URL you cite is bias (‘’)…No one favors impaired driving, but the question is, with dozens of studies stating otherwise, why are cannabis consumers still subjected to non-impairment testing?]

    [Paul Armentano responds: Um, nowhere did I state that there was a lack of temporary impact on cognition. Of course there is. But this impact is temporary and does not appear to be residual, even in people who have used the drug long-term. See: Lack of hippocampal volume change in long-term heavy cannabis users. American Journal of Addictions. 2005 | Neuropsychological consequences of regular marijuana use: a twin study. Psychological Medicine. 2004 | Non-acute (residual) neurocognitive effects of cannabis use: A meta-analytic study. Journal of the International Neuropsychological Society. 2003 | Current and former marijuana use: preliminary findings of a longitudinal study of effects on IQ in young adults. Canadian Medical Association Journal. 2002 | Neuropsychological Performance in Long-term Cannabis Users. Archives of General Psychiatry. 2001]

  15. Looks to me that the FEDS are just going to sue any state that tries to make their own law? Mind you I do not agree with the draconian law to profile Latinos. It just looks to me like this may be one instrument the Federal Government uses to make sure a law does not pass. Suing California an already bankrupt state could be devastating!

  16. our government already knows their is nothing wrong with cannabis. they know the truth……but they stand to lose much from its legalization. that is all it is.i believe ill be dead an gone before they would even consider legalizing the awesome little bud….damn our governments selfish asses…

  17. #67 The DEA would loose a large chunk of thier budget. Cancer treatment would loose a large chunk of thier income. Politicians would loose a large part of thier big pharma lobbiest income. Our gov cares not at all about our well being, only thier own bottom line. Sucks doesn’t it?

  18. Editor: agreed. I knew as I posted it that it wasn’t the best source. But regardless, although I don’t have the time to research it right now, there are probably other studies from other sources affirming the cognitive impact. Anyway, this is a topic that I am extremely interested in, and I wanted to see if anyone would be able to address the heart of my comment–and no one has, yet.

    The biggest issue that I have with legalizing marijuana is (1) cognitive impairment DOES result, (2) it is possible that people could be driving vehicles while so impaired, and (3) our police forces are unable to monitor/regulate the “highness” of drivers, so as to ensure that the roads are safe.

    The minute we can figure out how to create a device similar to a breathalyzer that can help police officers make those determinations, then I’m not sure if there are any rational arguments to be made against marijuana that aren’t morally charged.

    I know that this discussion could go off on this tangent for quite some time, so I’ll try to restrain myself from future comments 😉

  19. You speak of “cognitive impairment”, I assume you mean while high, because studies have shown that any impairment ends as the “high” ends. As far as driving while high, I realy wish people wouldn’t, I don’t. One thing you need to ask in this regard is, “when is the last time you heard of a horrible accident that ONLY cannabis was involved?” I have never heard of anyone driving like an idiot through an intersection, and killing an entire family high on cannabis. I have heard of far too many while people were drunk. Given my druthers I would have everyone on the roads SOBER, but if my only choices were between being on the road with 100 stoners, or one drunk, I’ll take the stoners every time.


    I’m just a twelve year old alien – but – for some unearthly reason, I don’t find this any less unique than I find a Featherless Pink Zig Zar unique. COULD IT BE ANY MORE EVIDENT TO YOU HUMANOIDS – to know that the human physiology has a Endo-cannibinoid System [which controls all other systems]. COULD IT BE ANY MORE CONCLUSIVE TO YOU HUMANOIDS – to point out that the two were [obviously] meant for each other’s use. WOULD IT SURPRISE ANY HUMANOID – to know that the human body produces anandamide all by itself.

    You’re all going to die!!! – rails the prohibitionists of your planet. Let me assure you – there’s never been a recorded death from its use. You can’t over-dose – it will only put you to sleep – leaving you refreshed in the morning. A ground floor suicide leap would be an easier way to commit suicide. For those who would [truly] believe they would become a raving addict or that death would occur – it’s absolutely necessary – to realize that it’s non-toxic and non-addictive. The only addiction you humanoids will get is an addition to the refrigerator. Right! – it’s a gateway drug to the refrigerator [the munchies I believe you call it]. That’s not a “bad thing.” Hemp is the most nutrtious food known to the rest of the universe. How come your earth leaders don’t know that? Does their intelligence fail them, or are they just plain stupid? I know the rest of the universe got a chuckle in their giggle bag when your human leaders made iot illegal. Man! there were crap detectors going off throughout the galaxy.

  21. The Corporatists await with baited breath for the day they can market Pot like they did tobacco.America may face an unreconcilable second dip depression and a re-evaluation of all that is American on the coming decades. To prevent chaos at this time and to grant solace to and injured people, legalized dope may be in order – but only after being refused as medicine, and as a “Special” consideration to calm the crowds. Americans are already self-medicated. Allowing for further tranquilization may save the corporatists a great deal of money.

  22. most people are missing the most important point and that is we can make gas with this plant. anything you can make from petroleum you can make from Cannabis,Hemp. go to the schaffer library of drug policy under unravelling an American Delemma:The Demonization of Marihuana, introduction Hidden Motives and you will get a good understanding of what is really going on, the Dupont-Mellon conspiracy to demonize Dupont’s major competition in the cellulose based industries. the big shots know All the good we can do with this plant from vegetable oil that we can eat to the best machine oil as the U.S. navy has said according to Jack Herer’s research. If we can make paper,rope,clothes,gas,oil,medicine, with protein in the seeds we can make food, replentish the soil,and plants give us back oxygen why as an intelligent society are we not looking honestly and seriously at all the good we can do with this plant and at a time when we need an annually renewable natural resource and a cash flow product. ( because the puppet masters pulling their green strings) We do need the meadia to spread the truth and we as Amricans do need to Unite and speak up to get the true change that we need and the true Greening of America. The law is a farce made up of lies and mis-informations and how can a law become a law when they broke so many federal laws to make up the marijuana tax act of 1937, they conspired to defraud the commonwealth(we the people)intentionally with lies and mis-informations to demonize their competition to create a monopoly abused government powers overriding free enterprize and fair competition laws

  23. and for you bible quoters I say to you Ezekiel 34:29
    “And I will raise up for them a plant of renoun and they shall be no more consumed with hunger in the land, neither bear the shame of the Heathen anymore.”

  24. Great article, i live in amsterdam and here it’s more or less legal. It’s illegal to grow cannabis on a large scale (u can own up to five plants) and sell it (unless u have a license), but you are allowed to carry up to 5 gram of it at any given moment. For the rest it’s ok if u decide to use it or not.
    I use it on a regular basis, i virtually quit drinking just because cannabis is better in almost any view.
    I’ll still have control over myself when i smoke a lot. No drawbacks like a raging hangover when u had too much alcohol. And al al these great studies show there are virtually no risks.

    One drawback i have to point out though is the fact that here in the Netherlands cannabis is made stronger and stronger through selection and special breeding techniques (special plant food, uv radiating lamps, etc.). Because of this duch cannabis is around 5-6 times stronger than the average u can get in say the united states or great brittain. And because of the potency of it there are greater risks atached, i’ve liiterly seen dozens of people with psychic disorders because of it (i work in healthcare and i see these people a lot). So here’s the note, just enjoy the plant as it is and don’t screw with it, It’s awesome enough as it is.

    P.s. Sorry for bad spelling and bad use of grammer, english is not my native language, so there’s bound to be some faults in here 😛

  25. Joe: just because it hasn’t happened doesn’t mean it can’t/won’t. I see your point, and I agree that drunk drivers are equally, if not more, frightening and dangerous.

    But, we still have a mechanism in place to be able to TRY to monitor drunk drivers. It doesn’t always work, and we don’t always catch them all, but we at least have the ability to try. It’s this ability that is lacking with regard to the marijuana issue.

  26. saliva testing can take care of the driving issue…too bad many…many feet are being dragged until our government runs out of excuses….

  27. As a child, I suffered from sleep deprivation. It was a struggle every night to sleep, right up to the time I started smoking marijuana and suddenly no more problems except twice in my life when i was not able to get it. I was working in Nebraska on a power plant shutdown and not being from there, I had no way to get pot. And the sleep deprivation returned. I was working 12 hour shifts and after three days of no sleep whatsoever, I called my supervisor and told him i was suffering from sleep deprivation and that I had to go back to California. Surprisingly he told me he had the solution to the problem and told me to come to his room. I didn’t know he smoked marijuana but thats what he had for me and he gave me a joint and that cleared up the problem till i returned to Cali.

  28. Very thorough. Could I see the 20,000 references that you used to write 9 paragraphs, please?

  29. It’s not what they don’t know, it’s what part don’t they understand. We have been telling them forever, that cannabis is good for you. Just to much money, to be made from cannabis smokers ,don’t want to lose a good thing!!!This will come back and bite all of them in the ass!!!! I only hope i am here to see that.
    DEA,FBI,CIA, and all the rest. What are they good for, absolutely NOTHING!!!!

  30. the past 10 years we are seeing more and more studies that show the medicinal benefits of cannabis, but the political interference that Big Pharma and its lobby has on medical licensing boards is limiting the real research we need to do with this plant here in the homeland… even with the studies we will still have the same interferance and its this interferance that we need to address…
    I’m pretty sure Big Pharma and their Lobby, IS involved in curbing medical doctors from making actual prescriptions for cannabis because its HUGE bucks for them and if people can get better results from a weed that can grown in there back yard they would stand to loose billions… but, one company IS marketing a cannabis extracts under the brand name Sativex and charging 300$ for a tiny jar.
    how retarded is that especially when you can make your own extracts using a couple shots of overproof vodka and a couple buds.

  31. Here we are again,

    When we decide to grow,will be changed
    in November.We the people shall make sure
    of this. I can`t see this going on any longer.
    My Vote is The entire U.S.A. Get LEGAL .A.S.A.P.

    Gary A. Parenti ,
    Peace & Happiness to everyone,

  32. Despite all of the evidence to the contrary, marijuana is viewed as evil and worthless. Why is that? I seriously don’t get it.

  33. The part of western civilization that has attempted to mask the shortfalls of its own leadership by creating a block between what seems to be want and need, should be reminded that the real issues at hand, namely the western economy, has failed as much as their attempt to block the progressive use of marijuana. If they spent as much time talking about how to create 19,000,000 jobs as they do enforcing the federal ban on marijuana, people might not be so inclined to grab the first joint they can find and toke up.

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