Marijuana Use Shrinks Teenagers' Brains

[t-pain]

when one organization does bad study after bad study, you start to see a pattern of confirmation bias, shoddy methods, and super big obvious conflict of interests.

 

do you remember the studies funded by the tobacco companies showing no lung cancer and no harmful effects for tobacco smoking?

that is one reason why we call into question the funders of the studies. because there can be sponsor bias.

 

that alone of course, is not a 100% proof of wrongdoing.

but it should make you skeptical. and you want to read it before agreeing with it.

[Restorium2]

I see. The knower of all has decided that the study couldn't possibly have been conducted because he knows it. There is just no possible way. Sounds a lot like the government contention that marijuana use and harder drug use go hand in hand or that marijuana is a gateway drug. Can't have done cocaine unless you first did marijuana right?  Wrong. Among the group I hung out with in my high school years drinking was not at all prevalent. Marijuana was the preferred "poison." That doesn't mean drinking wasn't prevalent in other places or even among other groups but suggesting that you know all and that there is no way this study could have been conducted is a bit arrogant.

 

Restorium2 has decided that there is no way a teen just smokes marijuana and that teens must also drink. You ARE really full of yourself aren't you?

Finding enough teens to make an honest study that had ONLY consumed marijuana? That's far fetched Frank. It would be impossible to prove. Edited August 12, 2014 by Restorium2

[t-pain]

guys cant you go compare dick sizes somewhere else?

 

does anyone even know the title of the study ? a link to an abstract ? its not even published yet i dont think.

[Restorium2]

does anyone even know the title of the study ? a link to an abstract ? its not even published yet i dont think.

There wasn't one when I started the thread. I linked the page it came from.

 

Do you think that there are many teens that only smoke marijuana? Just go right for that and stay there?

Edited August 12, 2014 by Restorium2

[knucklehead bob]

guys cant you go compare dick sizes somewhere else?

 

does anyone even know the title of the study ? a link to an abstract ? its not even published yet i dont think.

 

Is it corraberated ?

[FranksHotPeppersAndMarijuana]

Tpain this wasn't a NIDA study. I already told you that. It was a study conducted at the U of W at Milwaukee.

Edited August 12, 2014 by FranksHotPeppersAndMarijuana

[FranksHotPeppersAndMarijuana]

Add to that this researcher, Lisdahl, has done numerous studies on marijuana that could be seen as marijuana friendly. Including a current study that preliminarily tends to suggest that as long as teens are physically fit that there are no negative brain effects from marijuana.

 

So tell me zapatosunido who are these "they" that you speak of? U of W? Lisdahl? Who exactly?

[FranksHotPeppersAndMarijuana]

Yes if you read the thread you notice I mentioned that. But the point is that it isn't a NIDA study. Before you climb out on a limb with a suggestion that she tailors her studies to their liking you should do a bit more research on her body of work. As I mentioned she has done several studies that reveal good things about marijuana. Some which were also funded by NIDA.

[FranksHotPeppersAndMarijuana]

Different strokes for different folks. I prefer to read the primary source on my own and analyze the research rather than guess based on prejudices.

[FranksHotPeppersAndMarijuana]

Well I agree zapatosunidos. But medical usage isn't the issue as I stated. The issue is defeating the argument that it harms teens in non medical applications. If you read my posts in the thread you would see that my concern is the assertion that it damages teens which can be a hurdle to overcome in advocating for legalization. Granted this is a medical website so maybe I overstepped but the fact remains that to counter arguments from the other side you need to arrive fully loaded for bear. You accept proven arguments and then counter them. Ignoring a study with a cursory glance and chalking them up to propaganda won't help.

[FranksHotPeppersAndMarijuana]

Tpain, to respond to your desire to read the study I do have a pdf file of it. As I have said before I don't like conjecture or reading something from a secondary source.  I prefer to put my eyes on the real thing to determine what it actually says rather than believe some biased reporter as well as read study methodology myself.  I can email it to you if you PM an email address or maybe it can be transferred via PM?  It was published in the April addition of the journal "Current Addiction Reports."

[t-pain]

http://www.apa.org/news/press/releases/2014/08/considering-cannabis.pdf

is the one i found a few minutes ago.

 

unfortunately it is just a review of other studies

 

This review will summarize
current findings regarding the neurocognitive consequences
of cannabis use during the teenage and emerging adult years
(focusing on ages 15–25 years).

 

so to review this review, i will have to review the following studies

 

31. Solowij N, Jones KA, Rozman ME, Davis SM, Ciarrochi J,
Heaven PC, et al. Reflection impulsivity in adolescent cannabis
users: a comparison with alcohol-using and non-substance-using
adolescents. Psychopharmacology (Berl). 2012;219(2):575–86.

 

32. MedinaKL, SchweinsburgAD, Cohen-ZionM, Nagel BJ, Tapert SF.
Effects of alcohol and combined marijuana and alcohol use during
adolescence on hippocampal asymmetry. NeurotoxicolTeratol.
2007;29:141–52.

 

33. Medina KL, McQueeny T, Nagel BJ, Hanson KL, Yang T, Tapert
SF. Prefrontal morphometry in abstinent adolescent marijuana
users: Subtle gender effects. Addict Biol. 2009;14(4):457–68

 

34. Medina KL, Nagel BJ, Tapert SF. Cerebellar vermis abnormality
in adolescent marijuana users. Psychiatr Res Neuroimage.
2010;182(2):152–9.

 

35. McQueeny TM, Padula C, Price J, Medina KL, Logan P, Tapert
SF. Gender effects on amygdala morphometry in adolescent mar-ijuana users. Behav Brain Res. 2011;224(1):128–34.

 

36. Churchwell JC, Carey PD, Ferrett HL, Stein DJ, Yurgelun-Todd
DA. Abnormal striatal circuitry and intensified novelty seeking
among adolescents that abuse methamphetamine and cannabis.
Dev Neurosci. 2012;34(4):310–7.

 

37. Churchwell JC, Lopez-Larson M, Yurgelun-Todd DA. Altered
frontal cortical volume and decision making in adolescent canna-bis users. Front Psychol. 2010;1:225.

 

38. Ashtari M, Avants B, Cyckowski L, Cervellione KL, Roofeh D,
Cook P, et al. Medial temporal structures andmemory functions in
adolescents with heavy cannabis use. J Psychiatr Res. 2011;45(8):
1055–66.

 

39.• Cousijn J, Wiers RW, Ridderinkhof KR, van den Brink W,
Veltman DJ, Goudriaan AE. Grey matter alterations associated
with cannabis use: Results of a VBM study in heavy cannabis
users and healthy controls. NeuroImage. 2012;59:3845–51.A well
designed study examining impact of heavy cannabis use on corti-cal and subcortical brain structure in chronic cannabis users.

 

the conflicts of interest reported in the review:

Conflict of Interest Due to Krista Lisdahl’s efforts, the University of
Wisconsin-Milwaukee has received money in the form of grants from
NIH/NIDA for the current work. Dr. Lisdahl declares consultancy work
for the NIH/NIDA and travel, accommodations or meeting expenses paid
by INS, APA and NIDA, outside of the submitted work.

Edited August 12, 2014 by t-pain

[t-pain]

study 39, referred to as 'a well designed study' by the author.

http://www.researchgate.net/profile/K_Richard_Ridderinkhof/publication/51702522_Grey_matter_alterations_associated_with_cannabis_use_results_of_a_VBM_study_in_heavy_cannabis_users_and_healthy_controls/links/09e415072e5d445177000000

 

lets delve, shall we?

 

Cigarette smoking (%)

Marijuana group        CONTROL

70                              17

Duration cigarette smoking (year)

 3.7 (3.6)                   0.6 (1.5)**
Cigarettes per day

 7.0 (7.2)                   1.4 (3.5)**

 

70% of 33 marijuana heavy users is 23, so 10 marijuana users in the study did not smoke cigs.

 

i bring this up because.... we know tobacco smoking causes brain shrinkage

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

Smokers compared to nonsmokers had decreased anterior cingulate prefrontal and orbital frontal cortex gray matter volume and less gray matter density. Either gray matter volume or density was also decreased in the thalamus, cerebellum, and substantia nigra. Lifetime exposure to tobacco smoke correlated with decreased frontal, temporal, and cerebellar volumes.

 

i would say it is very difficult to seperate marijuana from tobacco brain shrinkage when 23 out of 33 of your study participants smoke 7 cigs a day on average for the past 3 years. which means you are basing an entire study on 10 people (who may or may not have been smokers, without the actual data its impossible to tell).

 

 

lets just let this 'well designed' study speak for itself?

 

 

Findings from the present study also imply that heavy cannabis
use is not necessarily related to structural changes in the forebrain
and striatum. Changes in grey matter may only be present in those in-dividuals that consume large quantities of cannabis almost daily with
symptoms of dependence. This might explain discrepancies between
previous studies (Ashtari et al., 2011; Block et al., 2000; Demirakca et
al., 2011; Jager et al., 2007; Matochik et al., 2005; Medina et al., 2007a,
2007b; Tzilos et al., 2005; Yucel et al., 2008) and is in line with the
idea that moderate cannabis use has a limited effect on frontal or
striatal grey matter whereas changes appear to be most likely in
long-term heavy and often dependent cannabis users (Lorenzetti et
al., 2010). Given the relatively young age and short duration of canna-bis use in this sample, more research is needed to clarify the relation
between regional grey matter volume and more severe dependent/
chronic cannabis use

 

 

 

what is your takeaway from that paragraph? maybe my english comprehension is broken.

it sounds to me like they found nothing and cant back even their basic theory up.

Edited August 12, 2014 by t-pain

[t-pain]

i'm not knocking a 10 person study. but when researchers make assumptions, estimations and guesses... its not great scientific method.

 

heres a very small double blind 15 person study of cbd for epileptics

http://www.ncbi.nlm.nih.gov/pubmed/7413719

this is a very simple study, there is no assumption. half are given placebo, half are given cbd.

placebo works for one of the control group and cbd works for 7 out of 8 of the cbd group.

this shows that cbd works better than placebo and that any other outside factors have not shown up in the control group results.

[FranksHotPeppersAndMarijuana]

I take it you didn't read the study I mailed you?  Just browsed through it?  If you read it then you would have seen that there isn't overlap on parts of the brain affected in the study with cannabis as compared to the study you posted on tobacco.  In fact parts of the brain that shrunk with tobacco use actually had increased mass in the cannabis study.  Similary, parts of the brain that shrunk with cannabis didn't shrink with tobacco.  You are comparing apples to oranges. There isn't one single correlation between the 2 studies as far a brain activity that I saw. So I really don't know how you are asserting that tobacco use was relevant in the cannabis study. 

 

Furthermore, had you actually read the study footnoted at footnote 39 that you referenced then you would have seen that the study included regression analyses to control for the nicotine use variable.

 

You are acting as if you have new ideas that the study authors never considered when in fact they not only considered them but made the proper adjustments for them. You can't just pull out parts of a study and address them independently. You need to view the entire methodology. I would also ad that the study did do toxicology screenings for other drugs through the course of the study.

[Restorium2]

I take it you didn't read the study I mailed you?  Just browsed through it?  If you read it then you would have seen that there isn't overlap on parts of the brain affected in the study with cannabis as compared to the study you posted on tobacco.  In fact parts of the brain that shrunk with tobacco use actually had increased mass in the cannabis study.  Similary, parts of the brain that shrunk with cannabis didn't shrink with tobacco.  You are comparing apples to oranges. There isn't one single correlation between the 2 studies as far a brain activity that I saw. So I really don't know how you are asserting that tobacco use was relevant in the cannabis study. 

 

Furthermore, had you actually read the study footnoted at footnote 39 that you referenced then you would have seen that the study included regression analyses to control for the nicotine use variable.

 

You are acting as if you have new ideas that the study authors never considered when in fact they not only considered them but made the proper adjustments for them. You can't just pull out parts of a study and address them independently. You need to view the entire methodology. I would also ad that the study did do toxicology screenings for other drugs through the course of the study.

Frank,

No one proved that a single brain shunk after using cannabis. It's all propaganda. Period. Incredible propaganda. I thought that when I posted this 'study' it would be so obvious it was because there's no way to do a study like this when there is no concrete way to determine use. It's all hearsay. Then when you see the claims made from hearsay you see the motivation to lie about cannabis to trump up findings. That's what this study is about and why I posted it.

 

What is most surprising to me is that someone posting here has enough cannabis hater in them to take the propaganda ball and run with it.

[Restorium2]

You can't base a medical study on anecdotal evidence.

 

The expression anecdotal evidence refers to evidence from anecdotes. Because of the small sample, there is a larger chance that it may be unreliable due to cherry-picked or otherwise non-representative samples of typical cases. Anecdotal evidence is considered dubious support of a claim; it is accepted only in lieu of more solid evidence. This is true regardless of the veracity of individual claims.

Edited August 12, 2014 by Restorium2

[t-pain]

So I really don't know how you are asserting that tobacco use was relevant in the cannabis study. 

 

Furthermore, had you actually read the study footnoted at footnote 39 that you referenced then you would have seen that the study included regression analyses to control for the nicotine use variable.

 

that was my point. they cannot magically control the nicotine use variable.

the regression analyses are bunk. they are guesses and estimations and assumptions.

 

 

Findings from the present study also imply that heavy cannabis

use is not necessarily related to structural changes in the forebrain

and striatum.

 

 

An important question arising from these results is to what extent

the observed structural differences are actually caused by heavy

cannabis use.

you read this in the study you emailed me, right?

 

they have no idea what causes the structural changes and they say it right there.

 

 

Alternatively, the observed structural differences

might be pre-existent

 

you read this sentence in the paper? did you understand it?

 

cannabis might make pigs fly out of my butt. better not use it.

Edited August 12, 2014 by t-pain

[Restorium2]

that was my point. they cannot magically control the nicotine use variable.

the regression analyses are bunk. they are guesses and estimations and assumptions.

 

 

you read this in the study you emailed me, right?

 

they have no idea what causes the structural changes and they say it right there.

Right. You can't use anecdotal evidence for regression analyses in medical studies. It's effective if you have known values for things you can measure like weight and blood pressure.

The study is looking at stories of past practices. Some testing was done in real time but it's not comprehensive enough when looking to past practices that could shrink a human brain.

[t-pain]

right. the study says marijuana causes memory loss and then asks the participants to recall past drug and alcohol use.

well if they have the memory loss, then they wont be able to remember that, will they???

 

this is what resto is talking about, you cant use self reported evidence in a double blind study.

its the same reason why the government says you cannot use anecdotal evidence of medical marijuana to show that marijuana works.

 

if the govt wont accept our anecdotal evidence of pro-marijuana benefits,

we're not going to accept the govt's anecdotal evidence of anti-marijuana effects.

Edited August 12, 2014 by t-pain

[t-pain]

So this recently published paper/article that we are talking about is just a review of all the other junk cannabis science that NIDA has paid for over the past few years? This is actually a full pile of junk science!

its the cheap way to have another 'study' that proves NIDA's point.

 

unfortunately , in the review it says many of these previous studies contradict each other. thus making the review itself contradictory and worthless for actual science.

 

but you see, NIDA just needs to use the title. NIDA knows no one reads the reviews or the original studies. these things could be 30 pages of lorem ipsum.

Edited August 12, 2014 by t-pain

[Restorium2]

And it made the national news again the day I posted it.

 

This is hurtful to parents of the children that use medical marijuana. It's wrong. It's mean. If it had an ounce of reality it would be scary. Thankfully it's totally bunk junk science propaganda. I thought it would be a 'no brainer' that it was ridiculous for everyone reading it. Hate is blinding. Does hate shrink your brain?

[t-pain]

lets put this another way, the govt loves doing research studies on rats and using those studies to "prove" that cannabis is bad.

 

so wheres the rat study that shows cannabis shrinks the rat brains ?

there isnt one. why not? is it because they couldnt shrink a rat brain with cannabis?

 

i know the absence of evidence is not proof, but wow is it damning when you think about it.

[t-pain]

you cant take children and force them to smoke marijuana and then cut open their heads and weigh their brains. so wheres the rat study??

 

bug spray might just shrink your darn brain.

http://www.sciencedaily.com/releases/2006/07/060713233619.htm

These effects were most prominent in the males, some of which experienced up to a 30 per cent reduction in brain region size compared to males at lower DDT exposure levels.

 

did these studies adjust for ddt exposure ? heh.

Edited August 12, 2014 by t-pain

[FranksHotPeppersAndMarijuana]

Tpain, you are pointing to a single sentence that you cut and pasted and suggesting that the sentence itself invalidates the study.  But you ignore the fact that the sentence deals with a discrete portion of the study that the study admittedly couldn't explain. Therefore the study gave a theory as to the differences in the portions of the brain that had changes for which the study couldn't accurately account. You also ignore the portions of the brain that were affected for which the study could account. Any study of anything will do this. It will present its findings and any findings that it cannot account for will theorize as to cause but not claim a particular cause. That has nothing to do with the other portions of the brain that showed direct correlations.  You did the same thing with the cigarette smoking where you made a blanket assumption that the study was bad because you didn't understand the study methodology.

 

Restorium2 it is nice that we have a genius here who is able to turn the entire scientific world upside down by asserting that regression analysis is bunk. You should publish your findings.

 

Virtually every study that involves a sample will use regression analysis to control variables. If you do a study on cannabis as related to controlling certain seizures in young children then there will be a regression analysis to control for variables such as diet and other factors. It is next to impossible to do a study where you can control all variable inputs when dealing with humans so a regression analysis is done. If you are doing a study on whether cigs cause lung cancer then you will do a regression analysis to control for whether there was a genetic component that caused the lung cancer AS WELL AS caused people to smoke (or want to smoke). Your idea that it is bunk basically means most every study ever conducted is bad. Using your theory there isn't a single study out there that is valid. How do we know that cig smoking causes lung cancer? Maybe the people who were smokers who got lung cancer also had a genetic flaw. Maybe that flaw not only caused lung cancer but also made someone more likely to want or need nicotine. So maybe it wasn't the smoke at all!

 

Tpain your claim that they couldn't have known whether they smoked cannabis because they had memory loss is ridiculous. The claim isn't that they had their memory wiped clean. Furthermore, you are ignoring that the researchers drug tested the individuals in the study on an ongoing basis. You are adopting restorium2's method which is throw everything at the wall to see what sticks.

 

Restorium2 you can claim it is all based on anecdotal evidence if you like. Just like you claimed that they couldn't know what other drugs the subjects took or whether they even knew it was cannabis they smoked. If you read the study you would have seen that the subjects were drug tested. That isn't anecdotal that is scientific. I thought that drum you were banging got a hole in it and was depreciated to zero. You must've gotten a new one that is still allowing you to make things up out of thin air. I would suggest you educate yourself on a topic before you claim to be an expert.