Study Finds Recreational Cannabis Use Is Associated With Abnormalities In The Brain

[mibrains]

http://www.iflscience.com/health-and-medicine/study-finds-recreational-cannabis-use-associated-abnormalities-brain   Study Finds Recreational Cannabis Use Is Associated With Abnormalities In The Brain

April 16, 2014 | by Justine Alford

Photo credit: Wikimedia Commons.

 

A study investigating recreational marijuana use in young adults has found that users had differences in two areas of the brain, the amygdala and the nucleus accumbens, when compared with non-users. The study has been published in the journal Neurobiology of Disease.

Cannabis, or marijuana, is the most commonly used illicit drug in the United States, but relatively few studies have investigated how it affects the brain. Although some animal studies have demonstrated changes in regions of the brain involved in learning and memory, attention and decision-making after exposure to the main psychoactive component of cannabis (THC), only a handful of similar studies exist in humans. The few studies that have been carried out also show contrasting results, which may be due to differences in methodologies. They also usually focus on heavy users as oppose to occasional users.

In this study, scientists used high-resolution MRI to scan the brains of 20 marijuana users and 20 non-users, between the ages of 18-25. The scans were used to collect data on gray matter density, brain volume and morphology. They matched the participants on age, sex, race and years of education. The marijuana users reported that they used the drug at least once a week, but were not dependent. The non-users had never used it more than 5 times in their lifetime. They also corrected for things like alcohol consumption as the users reported that they drank more alcohol than the non-users.

The researchers found that the marijuana users, compared with the non-users, had structural abnormalities in gray matter density, volume and shape of two areas of the brain; the nucleus accumbens and amygdala. These regions have been implicated in reward and aversion and therefore likely play a role in addiction. They are also involved in the euphoria associated with the rewarding effects of drugs.

The researchers also found that some of the abnormalities were exposure dependent. Finally, the researchers also suggested that cannabis use may be associated with a disruption of neural organization in the nucleus accumbens and amygdala, but this is speculation.

These data therefore suggest that recreational marijuana use in young adults may lead to alterations in the core reward structures. It's important to remember, however, that correlation does not imply causation- the study can infer an association but not a definitive cause. The number of participants was also small and the study did not investigate whether cannabis use affected cognition as well as brain morphology. Therefore although this particular study is important, it also lays the foundations for further in-depth research into this interesting area.

 

[mibrains]

They also corrected for things like alcohol consumption as the users reported that they drank more alcohol than the non-users.

 

 

i can't help but wonder how they might possibly compensate for that abnormality...

 

i did note that alcohol seems to play a larger role in those who refrain from cannabis according to this information..

 

by comparison since alcohol is deadly and cannabis is not... i feel like it is way past the time to change the status of cannabis and ensure proper research can be done...

 

interesting topic..

[trichcycler]

It's been suggested that some of these same abnormalities occurred in Albert Einsteins brain also. I believe it.

[+Malamute]

Hmm, so they say I have an aversion for reward. Hmm,...

 

I wonder if competitive athletes show a similar aversion for reward in their amygdalas.

 

But yea,.... just another study showing not much.

[GregS]

This is strange. Cannabis is reported to have neruoprotective properties and does, in fact, enhance brain cell growth. these people have apparently seen changes in structure, but do not legitimately connect those changes with pathology.

 

It sure would be great to have a highly trained and reliable doctor around to speak regarding the available information as it goes toward cognition and function. Those factors are only speculated about in this piece, and no definitive findings regarding the same are arrived at.

[t-pain]

i'd like to see raw-plant vegetarian brains compared to this study.

 

i wonder if its any plant cannabinoids that cause changes in the brain.

what i mean is, maybe its not the marijuana causing a change, but that its meat causing the change to your brain.

 

maybe the vegetarian brains are 'normal' and the meat-eater brains are 'abnormal' hmmm

 

Using MRI, the brains of 60 adults (20 omnivores, 19 vegetarians, 21 vegans) were scanned while they were shown images of human and animal suffering, alternating with natural landscapes. Basically, when compared to omnivores, vegans and vegetarians used different parts of the brain associated with empathy and social cognition in response to images of suffering, especially of animals.

i wonder if we can see the images in this study to see if the brains are differently shaped

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0010847

 

 

did this study test for tobacco vs marijuana smokers?

does tobacco change your brain? yes, yes it does. same with alcohol.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2631356/

 

i'd like to see this study replicated. any study that focuses on YOUNG MEN smokers sends up a red flag for me. why no young women? hmmm

[t-pain]

i saw a comment in a news article on this study, it mentions that the study goes to great lengths to mention recreational marijuana and legalized marijuana.

 

 

The results of this study indicate that in young, recreational
marijuana users, structural abnormalities in gray matter density,
volume, and shape of the nucleus accumbens and amygdala can
beobserved.Pending confirmation in other cohorts of marijuana
users, the present findings suggest that further study of marijuana
effects are needed to help inform discussion about the legaliza-
tion of marijuana.

 

except the study got 18-25yos. 

recreational marijuana laws in CO and WA are for 21+

 

its like saying you are studying the legal alcohol limit of 21 on drivers and then pulling records of 18, 19 and 20 year olds who have alcohol related accidents.

 

its dishonest.

[jointedone]

The ages of the participants were 18 to 25. Nothing about long term users. Kids 18 to 25 are already idiots until they grow up. Not a fair "study" at all.

[Guanotea1]

Very interesting note in the article re: correlation and causation. It shouldn't come at the end, the science behind this entire article is lacking. Much more interesting to know how cannabis use effects the brain over a period of heavy use than to be able to identify, in a TINY sample size, some differences in brain tissue between heavy vs. non-smokers.

 

Why does the media even put out "science" like this. They should not speculate on anything based on this study, it's a good datapoint for other scientists to work from (maybe) - but reporting anything this early in the scientific process is reaching.

 

People that do not understand the scientific process will read this article as affirmation that heavy cannabis is addictive and structurally damaging to the brain. That is not what the scientists are trying to say - I gaurentee it.

 

Correlation vs. causality?

What causes some people to become heavy cannabis users when others not? I could stay high 24-7 at this point, but I don't really feel like it. Others in the same position that I know (caregivers), choose much heavier usage. I have given this a lot of thought in the past, and obviously it comes down to "something in the brain", but what?

[Norby]

I heard of a study that showed that something about cb receptors in the brain and that "happy" people may have these receptors being fired at a higher rate naturally(without thc or cbd) while some people may get to that same state only by something outside the body that triggers these receptors more.  Don't quote me in the least as i just remember the "gist" of it and am terrible at remembering the right terms.  I can't remember if was that mj increased the receptors or just the amount they were fired.  Something along those lines though.

[Guanotea1]

Is it possible that they just like it more than you do? That's in the brain. Or maybe they are a patient as well as a caregiver? Ultimately, people just have different habits, right? Also, you say "stay high" but that means different things to different people with different strains and ingestion methods. Also, those that use cannabis less frequently experience more of a "high" than those that use cannabis frequently, which could explain some of the difference. I have met people who didn't want to smoke too frequently because they wanted to get super-high every time they smoked it. Others consider some of those "high" feelings to be a negative side effect that goes away with more frequent use, especially of the same strain or small group of strains. Also, I saw that this study had been thoroughly eviscerated here:

 

http://liorpachter.wordpress.com/2014/04/17/does-researching-casual-marijuana-use-cause-brain-abnormalities/

 

Nice link.. MY point is that people that like cannabis the most might naturally have different brain patterns than those that don't like it as much. Re-reading your post, you seem to get that. I am looking to the scientific community for a more specific answer, I suppose.

 

I say "stay high" and I mean that literally and yes I understand tolerance/strain-specific effects / etc. I couldn't do it forever, eventually my body would adjust I'm sure, but I could probably smoke a half a day, then move onto extracts, before staying high would even cost me any money- thanks to what is now my trash stash. And with all the different strains... you get the picture? Personally I'm not into stayin' high for long periods of time, and I strongly suspect, since I'm obviously pro-cannabis - come from a pro-cannabis family - and all my relatives are/were all heavy cannabis smokers except my dad- that it's my brain chemistry or structure that causes this. That could change, obviously, if I am ever afflicted with a lot of pain/nausea for a long period of time. So you've got a point about it not only being dependent on a person's genetics but also on their situation.

 

In case it's non-obvious I don't give a frak if you smoke a half joint a week, or 10 blunts a day, or not at all. AS long as you STFU and let people enjoy their peaceful life in whatever manner they choose, dowhatchawant :-)  

 

I've never met anyone that considered the high feeling to be a negative side effect, only the opposite, that is quite interesting. I have known many to say that this or that gets me too high, I don't want to be locked to the couch - etc. But never anyone that said that the feeling of being "high" is negative. Makes sense with all the high CBD strains out now, Thnks for bringing it up.

Edited May 28, 2014 by Guanotea1

[Guanotea1]

There's something to that Norby, the science of happiness. I'd love to see a longitudinal study on brain chemistry and the effect of various drugs prescription / recreational before and after. But I'm afraid I would understand it only slightly more than the person that wrote this article understands the science in question.

[outsideinthecold]

I heard if you used cannabis or if you didn't use cannabis you would still die anyway.

[cheapshades]

"Pot physically changes your brain (but so do music lessons)"

 

http://metrotimes.com/news/higher-ground/pot-physically-changes-your-brain-but-so-do-music-lessons-1.1673376

Edited May 28, 2014 by cheapshades

[in vivo]

MY point is that people that like cannabis the most might naturally have different brain patterns than those that don't like it as much.

 

It could come down to the expression level of receptors in the brain. 

 

I’ll use me as an example.  I stay “medicated” pretty constant. Lately I’ve been smoking a lot less since I’ve been supplementing with other cannabinoids.  Now let’s say that my natural expression level of CB1 receptors is high.  While I was never diagnosed I’d say I display ADD like symptoms when I’m not high.  I also have pretty severe social anxiety and sweat like a madman.  Remaining high allows me to bring my monkey mind under control.  It also seems to lessen the impact of stress and anxiety.  That might seem obvious but why might it be?  I would suggest that a reduction of the expression level and fatigue of CB1 receptors might be one possibility. AEA is increased when experiencing stress/anxiety.  In a brain with a high expression level this might be like giving a non cannabis user some headies with oil on top (ie panic attack).  It can create even more anxiety and paranoia.  Having the limited cognitive liberty that allows me as an adult to chose to lower my expression level of CB1 provides me therapeutic value.  

 

What if a person isn’t prone to anxiety and doesn’t display ADD like symptoms? What if they’ve got fewer CB1 receptors to start with? Please don’t attack me but quite possibly a lack of reward from stimuli which can account for a number of things, none of which would be that positive.  CB1 is so tied into the reward mechanisms that CB1 knockout mice don’t self administer morphine. That’s a huge statement. 

 

If you’re at the low end of the spectrum in terms of expression levels to begin with staying constantly medicated might not be as valuable as a person that might be at the high end of the spectrum.             

 

My .02    

Edited May 29, 2014 by in vivo

[Wild Bill]

Maybe the brains without cannabis exposure are abnormal. It might just be the cannabinoid receptors are just doing their job and this is what the human brain looks like when properly nourished.

 

I defy anyone to tell me Bill Shuette's brain is normal.

[GregS]

Here's the Real Story Behind That 'Marijuana-Changes-Your-Brain' Study

By Michael McCutcheon   April 17, 2014

•  
•  
•  

• 25
•  
•  

'Chances are you saw the headlines on Wednesday: "Casual marijuana use linked to brain changes," "Marijuana re-shapes brains of users, study claims" or "Casual marijuana use may damage your brain." Oh my god, marijuana is bad for my brain!

Not so fast.

"I think I saw one headline that was 'Marijuana reshapes the brain' and I groaned — that's not what we did," said Dr. Jodi Gilman, 31, author of the now-famous Harvard Medical School/Massachusetts General Hospital study on marijuana's effects, in an interview with PolicyMic.

Research is full of nuance, and nuance sometimes gets lost in the conversation. The collective freakout over this study had to do with its findings: Certain regions of the brains of people who smoke marijuana are structurally different than people who don't. That got interpreted, at least in headlines and ledes, as marijuana changes your brain.

"The conclusions were modest in the paper — we never say marijuana causes these changes," Gilman said, who's a neuroscientist with a Ph.D. from Brown University. "The media may have given that impression in headlines, but the study doesn't show causation."

It was a classic A and B study. Take group one and see how they're different from group two. That's it.

The experiment is a launching point for further research. It was conducted with 40 people from Boston, ages 18-25. Half of the participants used marijuana at least once a week but weren't dependent on the drug, and the other half weren't marijuana smokers. The smokers in the study, the experimental group, started smoking between the ages of 14 and 18 years old (16.6 years old with a standard deviation of two years). They were hooked up to an MRI, and Gilman and others found that the experimental group had structural differences in the nucleus accumbens and the amygdala regions of their brains (which relate to motivation and emotion).

 

MRI from the study, which shows (far right) where the marijuana group has greater brain density than the control group. Image Credit: Journal of Neuroscience

"The main point is there are differences in the brains of these two groups. The subtlety is we don't know if those differences are causal and relate to function or behavior," Gilman says.

There are at least a few different explanations for the differences and their meaning. For example, maybe people who use marijuana at a young age have natural differences in their brains. Or maybe a structural change in your brain, like a higher density amygdala, doesn't necessarily lead to good or bad effects.

There's way more research that needs to be done and that's Gilman's largest takeaway for others.

Since the study came out, Gilman has received a range of feedback. Some people criticize the small sample size — she states that the next step is to conduct the study with a larger group — or the funding source, the National Institute on Drug Abuse, among others (which got a laugh out of Gilman: "Your data is your data").

"Since this paper has come out, some people think I'm a crazy conservative against legalization," she says. "I don't think anyone should go to jail for using marijuana — people can do what they want — I just want them to know what's happening to the brain."

The reality, for even pro-legalization people like myself, is that there's a dearth of research on the effects of marijuana — a psychoactive substance that many states are considering legalizing. It'd be illogical to think that a psychoactive substance that gets you high doesn't affect the brain. By definition, it does and we should be honest about that.

"It took us 40 years to convince people that smoking cigarettes was bad for them and by then, people had all these negative effects. I don't want it to take 40 years to figure out the effects of marijuana," Gilman said.

That sounds reasonable to me, and until we know more, always be a skeptic.

 

http://www.policymic.com/articles/87875/here-s-the-real-story-behind-that-marijuana-changes-your-brain-study

 

Hmm. The marijuana group has greater brain density than the control group. Sure. It grows brain cells. Hell. We're smarter than we thought.

 

Edited June 5, 2014 by GregS

[GregS]

No, Weed Won’t Rot Your Brain

Can casual marijuana use damage the brains of young adults? A new study says yes—but its participants suggest otherwise.

All across the Internet, headlines are screaming Buzzkill and Marijuana Makes Young Brains Go to Pot. But a new study, published in the Journal of Neuroscience, does not in any way prove that casual marijuana use is bad for your brain.In order to understand why, all you need to do is actually read the research—and be able to think a bit critically. You don’t need to know anything particular about fMRI or any other scary acronyms and you don’t need to know your amygdala from your Shatner’s Bassoon. You don’t even need to know any statistics.

Here’s the first big problem. The 20 marijuana-smoking participants, who took the drug at least once a week, were deliberately selected to be healthy. If they had any marijuana-related problems—or any psychiatric problems or other issues—they were excluded from participating.

Are you beginning to see what’s wrong? Although the pot-smoking participants showed brain differences in comparison to the controls who were also selected to be normal—both groups were normal! If the smokers had any marijuana-related problems or any type of impairment, they would not have been included in the first place. Therefore, the brain changes that the researchers found were—by definition—not associated with any cognitive, emotional, or mental problems or differences.

“I’m disappointed that scientists are still able to publish high-profile papers that only look at neuroimaging without a behavioral endpoint,” says Carl Hart, an associate professor of psychology at Columbia University who was not associated with the research (Disclosure: he and I worked on a book project together). Hart compares the findings to brain differences found between the genders. “There are structural differences between men and women in certain areas,” he says, but they don’t predict differences in ability. “We don’t say this means women are impaired,” he adds.

The authors claim that the differences they saw could mean that these participants are at risk of future problems—but we know that 35 percent of young adults 18-20 have smoked marijuana in the past year, with a full 1 in 5 reporting smoking at least once in the past month.

 

“If the smokers had any marijuana-related problems or any type of impairment, they would

not

have been included in the first place.”

Once they reach age 26, however, less than 1 percent have marijuana problems serious enough to be classified as addiction. What that means is that whatever brain changes are seen in casual users, they don’t predict addiction, otherwise, all casual users would become addicted—or at least, a much larger proportion than actually do. We’ve already had several generations of American adults who survived far higher rates of marijuana use than we see now—without encountering a major epidemic of cognitive impairment, schizophrenia, or lack of motivation.

Sadly, this isn’t even the only issue with the study. “Just casual use appears to create changes in the brain in areas you don’t want to change,” lead author Hans Breiter, professor of psychiatry at Northwestern University Feinberg School of Medicine, told USA Today. But note that Breiter hedges by saying “appears to create,” rather than “creates.” That’s because this type of study cannot determine cause and effect: while it did show that the heavier users in the sample seemed to have more extreme changes than the lighter users, this does not prove that higher doses cause greater brain changes. That’s because pre-existing differences in people’s brains may lead them to use more or less marijuana— and the scans may simply be picking up on these differences.

Does this imply that marijuana is completely benign and everyone should smoke all day, every day? Of course not! But what it does mean is that, as we consider policy changes like legalization, we need a far more skeptical and intelligent press. Marijuana itself may or may not impair cognition— but discussions of marijuana policy clearly do so, in a way that is detrimental to our political health.

 

http://www.thedailybeast.com/articles/2014/04/17/no-weed-won-t-rot-your-brain.html

Edited June 5, 2014 by GregS

[GregS]

Neurology

Striking a Nerve: Bungling the Cannabis Story

Published: Apr 16, 2014

By John Gever, Deputy Managing Editor, MedPage Today

save

|

A

A

Correlation does not equal causation, and a single exam cannot show a trend over time. Basic stuff, right?

But judging by coverage of a study just out in the Journal of Neuroscience, these are apparently foreign concepts for many folks in the media.

In the study, researchers at Boston's Massachusetts General Hospital and Northwestern University in Chicago performed MRI brain scans on 20 young adult "casual" marijuana users and 20 age- and sex-matched nonusers. They found that, in the users, gray matter densities in the nucleus accumbens were higher than in controls, and the right amygdala and left nucleus accumbens were shaped differently.

Interesting, but remember that these findings only reflected differences between the marijuana users and controls at a single point in time. The researchers did not, could not, demonstrate that the differences resulted from marijuana smoking or even that the "abnormalities" relative to controls reflected changes from some earlier state.

You wouldn't know that from the media coverage. Here's a sampling of headlines:

• Marijuana News: Casual Pot Use Impacts Brains of Young Adults, Researchers Find (The Oregonian)
• Study Finds Brain Changes in Young Marijuana Users (Boston Globe)
• Casual Marijuana Use Linked to Brain Changes (USA Today)
• Even Casually Smoking Marijuana Can Change Your Brain, Study Says (Washington Post)
• Study Finds Changes in Pot Smokers' Brains (Denver Post)
• Recreational Pot Use Harmful to Young People's Brains (TIME)

Sad to say, the Society for Neuroscience (SfN), which publishes the Journal of Neuroscience, may have driven these dramatic overinterpretations by promoting the study in a press release headlined "Brain changes are associated with casual marijuana use in young adults."

Also note that the study did not identify any cognitive or behavioral abnormalities in the cannabis users versus controls -- it was strictly an MRI study.

That, however, didn't stop senior author Hans Breiter, MD, of Northwestern from opining in the SfN press release that the study "raises a strong challenge to the idea that casual marijuana use isn't associated with bad consequences."

Um, no, it doesn't -- not without before-and-after MRI scans showing brain structure changes in users that differ from nonusers and documentation of functional impairments associated with those changes.

To their credit, the study team's actual paper stuck fairly close to their data, concluding that the users showed "structural abnormalities." They only strayed into overinterpretation when they wrote that "the left nucleus accumbens was consistently affected by cannabis use." Nope, it was still just an association, no cause-and-effect shown -- as Breiter and colleagues acknowledged later in their paper.

It might also have been a stretch to call their subjects "casual users." The mean intakes were 3.83 days of use and 11.2 joints per week, and 1.8 smoking occasions per day of use. To me -- and I lived in Ann Arbor in the 1970s -- this sounds more like the profile of a just-short-of-heavy regular user.

I don't want to minimize the paper's genuine importance. The differences in brain structure from controls could well have functional consequences, and could well reflect the effects of marijuana use. Certainly these findings deserve follow-up.

But until we get it, everyone, please dial back the Reefer Madness hype.

Striking a Nerve is a blog by John Gever for readers interested in neurology and psychiatry.

[t-pain]

peer reviews huh?

[GregS]

peer reviews huh?

Uuh, yup.

[MedicatedJester]

By the math above (3.83 sessions a week, 1.8 sessions per intake day, and 11.2 joints a week) means they averagesd1.6 joints PER SESSION. For a CASUAL user. These users were either smoking TERRIBLE pot or were getting RIDICULOUSLY high.