Pot smoking may cause permanent brain damage

23536

23536

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Researchers at the University of Maryland studied mice to look at how marijuana use during adolescence impacts those still-developing brains. A group of adolescent mice were exposed to low doses of the active ingredient in marijuana for 20 days, then returned to their sibling groups to continue maturing.

When the mice reached adulthood, the researchers examined cortical oscillations (patterns of neuron activity in the brain) and found that the mice who had been exposed to marijuana had greatly altered cortical oscillations and impaired cognitive abilities. The researchers then exposed adult mice to the same levels of marijuana's active ingredient. Surprisingly, the adult mice didn't show the same alterations in cortical oscillations and had no changes in their ability to perform cognitive behavioral tasks.

These results don't bode well for teenagers who decide to dabble in drugs. "The striking finding is that, even though the mice were exposed to very low drug doses, and only for a brief period during adolescence, their brain abnormalities persisted into adulthood," said the study’s lead author, Sylvina Mullins Raver.

cont. http://healthyliving.msn.com/blogs/...=3e023b74-3f7a-4a3e-baee-ed52039eb258&_nwpt=1
 
abstract:

Adolescent Cannabinoid Exposure Permanently Suppresses Cortical Oscillations in Adult Mice

Sylvina M Raver, Sarah P Haughwout and Asaf Keller

Abstract
Regular marijuana use during adolescence, but not adulthood, may permanently impair cognition and increase the risk for psychiatric diseases, such as schizophrenia. Cortical oscillations are integral for cognitive processes and are abnormal in patients with schizophrenia. We test the hypothesis that adolescence is a sensitive period because of the active development of cortical oscillations and neuromodulatory systems that underlie them. The endocannabinoid system upon which marijuana acts is one such system. Here we test the prediction that adolescent cannabinoid exposure alters cortical oscillations in adults. Using in vitro local field potential, in vivo electrocorticogram recordings and cognitive behavioral testing in adult mice, we demonstrate that chronic adolescent, but not adult, cannabinoid exposure suppresses pharmacologically evoked cortical oscillations and impairs working memory performance in adults. The later-maturing prefrontal cortex is more sensitive to adolescent exposure than the earlier-maturing, primary somatosensory cortex. These data establish a link between chronic adolescent cannabinoid exposure and alterations in adult cortical network activity that underlie cognitive processes.
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http://www.nature.com/npp/journal/vaop/ncurrent/full/npp2013164a.html
 
slimvictor said:
This is important, and interesting, but the title should read

Adolescent pot smoking may cause permanent brain damage
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Maybe "adolescent pot smoking in mice may cause brain damage" would be an even more accurate title. I remember reading somewhere that a drug was perfectly safe in mice with a high LD50 and ended up very poorly in human testing. I'm sure that's not an isolated case either. I understand that mice are a good indicator of what may happen in humans, but they aren't humans.

Still, I'm not advocating that pot is harmless to children, in fact I don't think that children should have any mind altering substances until their brains are at a certain stage. Adulthood doesn't necessarily mean that the brain is fully developed, but I guess a line has to be drawn somewhere.
 
nobody remembers the human study a year ago which found exactly the same thing?

Here's that thread:

http://www.bluelight.ru/vb/threads/639299-Teenage-pot-smoking-may-lower-IQ-–-for-life

The persistent use of cannabis before age 18 has been linked to lasting harm to intelligence, according to a large study.

Analysis of more than 1000 New Zealanders found those who took up cannabis in adolescence and used it for years afterwards experienced an average decline in IQ of eight points when measured at age 13 and 38.

People who did not begin using cannabis until they were adults, with fully formed brains, did not show the same declines.

Experts here and abroad say the findings are significant and could offer some explanation for the "teenage stoner" stereotype.

Lead researcher Madeline Meier of Duke University in Durham, North Carolina, said quitting cannabis later in life did not appear to reverse the loss of intelligence.

Higher IQ correlated with higher education and income and better health, she said.

"Somebody who loses eight IQ points as an adolescent may be disadvantaged compared to their same-age peers for years to come."

The study, to be published in the Proceedings of the National Academy of Sciences, examined individuals in the Dunedin Cohort study, which has followed 1037 people born in 1972-73 in Dunedin from birth.
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So the implication here, to me, is that if you try cannabis once as a teenager, you might as well become a super stoner beecause you've damned your memory and intelligence irreversibly.
 
Psychedelic Jay said:
It’s the other way around...
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I don't get it. For thousands of years, marijuana was simply referred to as cannabis. Are you saying that the cannabis plant was named after a system in the human body? I highly doubt that people had the scientific knowledge thousands of years ago to even know what the endocannabinoid system was.

Please elaborate on what you mean by this. It's kinda confusing.
 
Cannabinoid receptors were named that way after they were discovered to bind cannabinoids. After the receptors were discovered, it was theorized that they had endogenous ligands. Indeed they did, and these were called endocannabinoids.

I think what Psychedelic Jay meant is that plants developed cannabinoids to interact with the endocannabinoid system already present in animals.

This is fascinating stuff that dates back hundreds of millions of years. Many people don't realize that animals predate flowering plants.

See Science Daily article about flowering plants:

http://www.sciencedaily.com/releases/2010/03/100315161919.htm
 
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23536 said:
Cannabinoid receptors were named that way after they were discovered to bind cannabinoids. After the receptors were discovered, it was theorized that they had endogenous ligands. Indeed they did, and these were called endocannabinoids.

I think what Psychedelic Jay meant is that plants developed cannabinoids to interact with the endocannabinoid system already present in animals.

This is fascinating stuff that dates back hundreds of millions of years. Many people don't realize that animals predate flowering plants.
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This.

It is theorized that the plant developed these “noids” to deter herbivores and omnivores alike... Not to harm, but deter...

It is classified as an intoxicant. Household pets do not enjoy weed like we do. It mind-fucks them. That is exactly what it is meant to do.

We on the other hand have grown to build a liking to it. Some of us including myself get the classic effects meant to be gotten... Dread and panic.​
 
Psychedelic Jay said:


This.

It is theorized that the plant developed these “noids” to deter herbivores and omnivores alike... Not to harm, but deter...

It is classified as an intoxicant. Household pets do not enjoy weed like we do. It mind-fucks them. That is exactly what it is meant to do.

We on the other hand have grown to build a liking to it. Some of us including myself get the classic effects meant to be gotten... Dread and panic.​
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How would animals be smart enough to know what an intoxicant is? Would that knowledge be imprinted in their genes?
 
Dietary choices are determined by genetics. The animals that like the flavor of the intoxicating plant will come under its effect and perhaps get eaten or perhaps miss out on mating opportunities. Fewer of the cannabis-liking animals will pass on the cannabis-liking gene, and over millions of years it will diminish and/or disappear.
 
sekio said:
So the implication here, to me, is that if you try cannabis once as a teenager, you might as well become a super stoner beecause you've damned your memory and intelligence irreversibly.
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I rather severely doubt this. Not only do rats show significant differences to primates in responses to e.g. MDMA and PCP w.r.t. axonal pruning in 5-ht receptor-expressing neurons and the appearance of Olney's lesions respectively, but also adolescence as a phenomenon is markedly different in rat and human brains. Human adolescence marked by a "growth spurt" following a childhood lacuna is not a common feature of animal development and it is therefore not entirely clear, unless I am mistaken, whether an adolescent rat is more closely analogous to a 19-year-old human or to a 9-year-old human. In particular, an "adolescent rat" is generally defined as one that is between 6 and 24 weeks old.

Of course, you're sekio, so you were probably joking.

Psychedelic Jay said:
It is classified as an intoxicant. Household pets do not enjoy weed like we do. It mind-fucks them. That is exactly what it is meant to do.

We on the other hand have grown to build a liking to it. Some of us including myself get the classic effects meant to be gotten... Dread and panic.
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False and double-false. Cannabinoids are self-administered by rodents, and furthermore the only "intended" effect of any plant compound is "make the jerkoff herbivores stop eating me".

http://onlinelibrary.wiley.com/doi/10.1038/sj.bjp.0707465/full
 
23536 said:
nobody remembers the human study a year ago which found exactly the same thing?
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I remembered it, but that study showed that persistent smoking of cannabis by adolescents caused a drop in IQ, which is really different than showing that low doses administered (presumably not via smoking) to mice cause cortical oscillations.

For one, I consider IQ to mean very little, and what it does mean is only peripherally related to "intelligence".
For another, persistent smoking of anything in adolescent humans could cause lower IQs.
So, in a way, I am more impressed (and worried :sus:) by the mouse study.
 
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