"Young adults who used marijuana only recreationally showed significant abnormalities in two key brain regions that that are important in emotion and motivation, scientists report. This is the first study to show casual use of marijuana is related to major brain changes. It showed the degree of brain abnormalities in these regions is directly related to the number of joints a person smoked per week."

http://www.sciencedaily....2014/04/140415203807.htm

So the scaremongering crowd are screaming "brain damage!" and such, but could people be jumping to conclusions here?? The brain is a dynamic and plastic organ and is moulded and altered by many different types pf experience, so such changes may not be permanent, and may not be detrimental. Changes in brain structure have been linked to meditation and with long term ayahuasca use recently...such changes are likely going to be different to those observed with cannabis but these changes aren't viewed as detrimental (if anything, the opposite). Cannabis use by the young, whose brains are still developing, could definitely entail risk. But if cannabis is one of the most widely used substances in the world, and causes "significant abnormalities" in the brain with even low level use, where are these tens of millions of brain fried zombies?? Professor David Nutt cautions people about drawing set-in-stone conclusions from a sample of 40 people, and states “Whatever cannabis does to the brain it's not in the same league as alcohol which is a proven neurotoxin.”

Study:

Jodi M. Gilman, John K. Kuster, Sang Lee, Myung Joo Lee, Byoung Woo Kim, Nikos Makris, Andre Van Der Kouwe, Anne J. Blood and Hans C. Breiter. Cannabis Use is Quantitatively Associated with Nucleus Accumbens and Amygdala Abnormalities in Young Adult Recreational Users. Journal of Neuroscience, April 16, 2014 (in press)

"Young adults who used marijuana only recreationally showed significant abnormalities in two key brain regions that that are important in emotion and motivation"
This gives me some concern, as I've been talking with a few friends recently who have been smoking cannabis in the last year or two and have noticed they've been really un-motivated. I've noticed it myself, although I smoke once a week to relax and unwind.
I really hope this is not the case but if it is I may just stick to tryptamines...

The term "abnormalities" the authors use to describe the structural deviations found in brain parameters of recreational marijuana users does have negative connotations and should be avoided in (a utopian) scientific community...

Increased grey density matter in the the left nucleus accumbens might very well be seen as a potentially good thing (but that's a double-edged sword anyway). Decreased in overall grey matter density (~1.4% less compared to controls) and white matter density (~2% less compared to controls) is usually seen as a negative thing, hence the term "abnormality". Not that it couldn't be a positive thing but who knows. It is close to impossible to extrapolate from neurological data to what it actually means for a person to have altered brain parameters.

Full paper here:

http://jn.sfn.org/press/...Issue/zns01614005529.pdf

A sample size of 40 people is ridiculously small, 20 normal vs 20 control is not enough to really make any reliable statistical conclusions, anybody working with statistics knows that.

Also they say: ¨Marijuana users reported drinking a greater number of alcoholic drinks per week than control participants ¨. I´d have to look more into their statistical use but I´m not sure how they can make any analysis with such a small sample plus considering the marijuana group had cigarrete smokers and drank more alcohol than control group.

In one quote they say ¨The present study demonstrates that, even in young, nondepen-
dent marijuana users, morphometric abnormalities relative to nonusers are observable, many of which are exposure dependent¨ -> Pure speculation, they can only talk about the marijuana users in that specific sample, yet the sentence implies a generalization. That´s not good science.

Also they talk about `cannabis use` but they do not take in account that marijuana use can also be through vaporization or oral use.

The study is funded by NIDA, which makes is suspicious IMO. The title choice for the word `abnormality` shows a bias IMO, they could have chose `changes` or `differences` or a more neutral word, but with their choice of word it implies a negative thing without actually proving the changes are negative.

Now looking at the changes themselves, what do they mean? The study claims there was an increased density in grey matter in amygdala and left nucleus accumbens. What can that mean? A search in google reviews that mindfulness practices and reduction of stress increase grey density in amygdala:
http://www.sciencedirect...le/pii/S092549271000288X
http://intl-scan.oxfordj....org/content/5/1/11.full

Is this study maybe just showing marijuana users are more mindful and less stressful ? LOL

(then again, other studies show the inverse with different types of mindfulness... see how complex this is and how careful we must be with conclusions? http://www.plosone.org/a...1%2Fjournal.pone.0064574 )

I´m not saying cannabis is completely harmless nor that there isn´t something interesting to continue exploring in this area but this particular study seems biased, overgeneralizing, unreliable in sample size and using misleading affirmtions.

I don't know about you guys, but I didn't need a science paper to tell me how unmotivating cannabis can be...

I read thi article somewhere else and it doesn't sound scientific but manipulative:

How is possible to follow such a large number of young people who are "heavy marijuana smokers"?

First it is illegal drug to start with, or has it be legal all this time in New Zealand? Second if you have contact with under age unreasonable smoking I think one is legally obliged to report it at least to parents... Who are the kids in the study, disclosing it freely.... Don't get it, these scientists if true, are very irresponsible human being to say the least. Something is very wrong here.

The sample size may be small, but the nature of these studies makes it difficult to have large enough sample sizes. For as far as human studies of this style are concerned, 20 people is an good starting number. This is a limitation that the authors also acknowledge.

The MJ group had higher intake of alcohol, but according to the authors this was corrected for in their analyses. Granted, these corrections are never perfect but then again there is no other way around when you deal with real life situations i.e. people and not laboratory animals.

Overall, I believe that this is a honest study and that the only caveat is the the negative term the researchers used to describe the differences. The NIDA funding also does not imply anything negative or biased either. NIDA does all sorts of things apart from being a governmental institute complying with the governmental agenda. NIDA is a true asset if you are doing research relating analysis/identification/quantification of chemicals in human or other samples. They are, for most of the time quite professionals and I personally wouldn't think that association with NIDA means something wrong. Plus, the researchers received funding from 6 other different sources as well.

Thank you for your view Inf.

Did NIDA ever fund a study that does not have a negative view of ´recreational´ drugs?

Another aspect I noticed is that they claim in the conclusions they used parametric statistical analysis but in my understanding you cannot meet parametric analysis criteria comparing groups with less than 30 subjects. But im no expert and this is based on one statistics class I took and my ex boss which instructed me when I had to work with statistics a couple of years ago.

Also I couldnt help but notice they mentioned the study should `help inform` the debate of marijuana legalization, and though that may be a personal view of mine, the debate on legalization is about a personal choice and sovereignty over one`s body, not about whether one or another study shows one or another effect of a drug. I see no mention in the studies from the same author debating alcohol`s effects that it should be made illegal even though it also supposes neurobiological changes (e.g. http://www.jneurosci.org...28/18/4583.full.pdf+html ) so why the double standards? By the way, funny title from the author somehow or another admitting his own alcohol use

After i had started smoking and stopped once, i started thinking of marijuana like this. It just makes you feel better about doing nothing. I was very unmotivated because i was content just sitting there stoned. I feel like any affects on the motivation part of the brain should be relatively temporary, because when i stop smoking i always get a nice boost in motivation after a couple days of not smoking.

Im not sure if the study is in any way related to motivation though.. The brain areas they mention are related to pleasure/reward if I understand correctly.. As if they are trying to probe into the neurobiology of marijuana addiction.

In any case, regarding the motivation aspect, I think for me it´s more about being unmotivated to do things I dont want, but being motivated to do things I like (playing guitar, walking in nature, listening to music, having good food, etc).

I am currently taking a break from cannabis, even though I also really appreciate it. I think that as with anything we habituate ourselves with, it´s good to step back and do something different, so as to gain a broader view, get a better perspective on ourselves, and gain more appreciation for things. I think we humans tend to get too used to things so its always good to not keep doing the same thing regularly forever, unless it´s really something 100% healthy and beneficial. With cannabis for some people using for medical reason I understand, but for those that aren´t and it´s more ´recreational´, I think there are could be significant downsides with daily/excessive use. But this depends on each one to find out what works best for them, there´s no fixed rules here. But this is totally unrelated with this research imo

My experience with cannabis (daily use) was that I would not get upset so quickly and so much. Also, after not smoking for a few weeks, I would notice an increased "tunnel vision" with respect to motivation. As if indeed, cannabis allows one to easier step back and look around.

Cannabis can also make me feel tired and low on energy, but I'm not sure if that is not related to blood sugar levels more than brain structures.

Anyway after so many years I realized I got the message (relax, look around, smile!), so I hung up the phone.

Parametric statistical tests are appropriate for this study as the data relates to intervals and ratios (eg measurements of the areas in question, compared); non-parametric tests are for nominal or ordinal data. The number of subjects is less relevant than the type of data collected.

No problem

Good point re NIDA, however I think it is the publication per se of a study rather than the premeditated outcome of a research that has been funded that NIDA is all about. That is, a NIDA-funded study may not get published if no effects are found when a substance of (ab)use is researched and a study may get published if effects are found (like in this case, where effects are found but are presented in a partially negative light by the authors and grossly negative light by the press).

There is another factor that doesn't help much, i.e. that negative results or absence of an effect are hardly ever publishable. It is indeed hard to "sell" negative results. As for statistics, you can use parametric tests even in small samples as long as you have a good reason to do so, like you did a test to check whether the dataset is Normally distributed.

Finally, good point about the author. Mind you, only the first author is the same in cannabis and alcohol papers, the rest are different; the alcohol study was from 2008 from when the fist author worked in Maryland and the cannabis from 2014 from Massachusetts where this person works now. Even though the first author is the guy who writes most of the text and/or does many of the experiments in a study, it is very often that the views of last author (aka the Grant Boss) that will dictate, direct and proofread the manuscript, so comparing the two articles solely because they have the same first author may not yield much. Sometimes first authors write articles solely because they were instructed to do so or because it is part of their job description or because the first and last authorship are the ones who matter in the politics of science and publications and budding researchers want to write and publish as much as possible.

They say weed smoking makes one apathetic too, but I don't really care.

I know of at least one weed-smoking workaholic in this group.

Just last summer I worked a full-time job, got my drivers licence (don't know how it goes in other places but in Spain it's a huge PITA) and trained BJJ daily. All this during my honeymoon phase with my Volcano vaporizer, so I'd be inclined to call BS on the "weed makes you dumb and lazy" argument .

This is such nonsense for so many reasons I feel I can't make a short post and explain why there is such dense failage with it.

This study, besides being funded by the National Institute on Drug Abuse, was also funded by the Office of National Drug Control Policy and the Counterdrug Technology Assessment Center - who make money from keeping substances like Cannabis illegal. There is a good rebuttal to this study here. http://www.medpagetoday....y/GeneralNeurology/45290

I had one friend in highschool who used to smoke to get the motivation to clean her home. She'd smoke a joint and it was like releasing a tornado of cleanliness.

My best friend smokes as it's the only thing that has help his bipolar disorder. He's also the most ambitious person I know, running several self made business. He wakes and bakes everyday at 5:30am and works till 8:30 pm, smoking the whole time.

I have a co worker that gets overwhelmed with the daily activities unless he smokes. He is happier and more productive because of it.


Me: I'm a nightly smoker, when everything is done and accomplished, it's lets me deal with things of my past so I can sleep better. It's my reward and relaxation at the end of the day. I am the unmotivated type on it and I know it. So I only use it when I feel like being in such a state. It makes little things for me like walking the dog, or a late night trip to the store a "stoner odyssey", as I like to call it


This study forgets how most grown people are responsible adults. It also forgets how most young people are naturally not motivated to do non pleasure seeking activities.

LOL, it's the booze I'll bet. Too bad they didn't screen the study participants to examine youth who smoked weed but did not do other recreational drugs including alcohol, tobacco and caffeine. Sure they would have a difficult search to find youth who meet these types of parameters, but the results would be more meaningful. A study involving thousands of participants done longitudinally over say 20 years, looking each year would carry more weight.

Hmmm, there was some other point I wanted to make. . . . I forgot. . . .(Pandora wanders off to eat a cookie).