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Opty
10-02-2006, 09:17 AM
Study Finds No Cancer-Marijuana Connection

By Marc Kaufman
Washington Post Staff Writer
Friday, May 26, 2006; A03


The largest study of its kind has unexpectedly concluded that smoking marijuana, even regularly and heavily, does not lead to lung cancer.
The new findings "were against our expectations," said Donald Tashkin of the University of California at Los Angeles, a pulmonologist who has studied marijuana for 30 years.

"We hypothesized that there would be a positive association between marijuana use and lung cancer, and that the association would be more positive with heavier use," he said. "What we found instead was no association at all, and even a suggestion of some protective effect."

Full Article Here. (http://www.washingtonpost.com/wp-dyn/content/article/2006/05/25/AR2006052501729.html?referrer=delicious)

Mac H.
10-02-2006, 09:57 AM
You forgot to include this rather important snippet in your quote:


Tashkin said that while he still believes marijuana is potentially harmful, its cancer-causing effects appear to be of less concern than previously thought.

Mac

Opty
10-02-2006, 10:25 AM
Taskin's referring to the psychological/neurological harm marijuana can potentially cause, not the cancer risk. Even so, marijuana's "potentially harmful effects" are grossly exaggerated in the media, anyway.

Ritalin (and Adderall) is much more harmful for you than pot, and parents feed their kids Ritalin like candy these days.

Digressing...

My post and the article are about the cancer risk, so that snippet isn't important at all to the issue.

WDS
10-02-2006, 10:54 AM
I am curious how bad pure, organic tobacco leaves would be if smoked. Would they be nearly as bad as they currently are?

Bravo
10-02-2006, 03:34 PM
spork, do you write out prescriptions for medicinal use?

Peggy
10-02-2006, 10:01 PM
Interesting study. I was always under the impression that the damage caused by smoke to the lungs was one of the risk factors in lung cancer. If they are right that THC helps clear out old damaged cells, then the obvious solution is to add THC to tobacco cigarettes. Right?

Shadow_Ferret
10-03-2006, 02:14 AM
I am curious how bad pure, organic tobacco leaves would be if smoked. Would they be nearly as bad as they currently are?

Those are called cigars. Go ahead. Inhale.

WDS
10-03-2006, 06:08 AM
I don't smoke, and I never intend to unless I light myself on fire for some reason.

MattW
10-03-2006, 06:11 AM
Mary Jane - certifed organic, vegan friendly, gluten free.

Now with no carcinogens!

brianm
10-03-2006, 03:49 PM
It is still illegal. Was this posted for information purposes or are you posing a question?

veinglory
10-03-2006, 05:18 PM
The proven harms are not only psyc/neuro - there are some effects on fertility and chances of birth defect.

Shadow_Ferret
10-03-2006, 05:54 PM
The proven harms are not only psyc/neuro - there are some effects on fertility and chances of birth defect.

Don't forget man boobs.

Bravo
10-03-2006, 06:08 PM
It is still illegal. Was this posted for information purposes or are you posing a question?

so?

that really has no relevance to this discussion.

personally i dont do pot, im disdainful of really anything that chemically alters your perception of the world and your surroundings. (unless it were for medicinal use, say youre in chronic pain and pot helps you live day to day.)

ive seen a lot of kids who have used it as a crutch for their psychological problems and became emotionally numb/stagnant.

but none of that means that the government should claim it's more physically harmful than it really is.

Shadow_Ferret
10-03-2006, 07:18 PM
im disdainful of really anything that chemically alters your perception of the world and your surroundings.
So you don't even have a beer?

Soccer Mom
10-03-2006, 07:39 PM
Yeah, I hear all the stuff about how pot isn't harmful. All I know is that I run up against old potheads all the time in my job. I have to explain everything to them like ten times and write it down and they still don't get it. Of course, they are still more with it than the huffers who just stare blankly, but still. Ummm, no thanks.

Shadow_Ferret
10-03-2006, 08:00 PM
I have to explain everything to them like ten times and write it down and they still don't get it.

Huh? What? Could you repeat that?

Bravo
10-03-2006, 08:09 PM
that's cool, man.

WerenCole
10-03-2006, 08:21 PM
Unlike cigarettes which more or less come in one form, people who smoke the hippie lettuce have lots of choices. Some forms of smoking are better than others. . . water filtration, glass aparatus etc. The tar intake in a joint is higher than say, a bong. Any pothead knows that you can get just as bad a cough (or worse) from smoking pot as smoking cigs.

But hey, at least it won't contribute to cancer!

Opty
10-04-2006, 12:09 AM
The proven harms are not only psyc/neuro - there are some effects on fertility and chances of birth defect.

The "proven" psychological/neurological damage caused by marijuana have been grossly misreported and overexaggerated. However, the effects on fertility and chance for birth defects are no greater than those caused by tobacco use while pregnant or alcohol consumption while pregnant. In fact, alcohol poses a much greater threat (to general health and fetal health) than marijuana could ever hope to.

I am by no means advocating the use of marijuana for recreational purposes. However, it's not nearly as bad as the government and certain conservative advocacy groups would (mis)lead you to believe. In fact, there are several therapeutic uses for THC/cannabinoids which show much promise.

Many people let myth and propaganda control their biases. In fact, these faulty biases become so strong in some people that they remain intransigent in their views, even when presented with overwhelming scientific evidence to the contrary.

If we want to tell our kids that certain drugs are "bad," we should at least do it with accurate, factual information. Lying to them with "reefer madness"-type propaganda only increases their chances for substance abuse.

I'm just doing my part to spread the facts and dispell the myths.

Opty
10-04-2006, 12:12 AM
Yeah, I hear all the stuff about how pot isn't harmful. All I know is that I run up against old potheads all the time in my job. I have to explain everything to them like ten times and write it down and they still don't get it.

Yes, but chances are they were stupid before they started using. It's more likely (based on scientific evidence) that morons are attracted to pot than it is that pot creates morons.

Mac H.
10-04-2006, 01:29 AM
I'm confused here. Your aim is to spread the facts and dispel the myths.

Great. So why are you mentioning certain facts ("doesn't contribute to lung cancer") but not others ?

Sure, the media and your government may be biased and ignore certain facts, but surely it is just as reprehensible to respond by doing the same, but in the opposite direction ?

Here are some of the facts:

1. One of the effects of marijuana use is problems with memory and learning.
Ref: Pope, H. G. and Yurgelun-Todd, D. The Residual Cognitive Effects of Heavy Marijuana Use in College Students. Journal of the American Medical Association, Vol 275, No. 7 (1996)

2. One of the effects of marijuana use is problems with thinking and problem solving.
Ref: Harder. S. and Reitbrock, S. Concentration-effect relationship of delta-9-tetrahydrocannabinol and prediction of psychotropic effects after smoking marijuana. International Journal of Clinical Pharmacology and Therapeutics (1997)

3. Despite making you stupid (see above) it doesn't cause lung cancer. (See original discussion)

I can't find a proper reference to the biggest study - the Swedish one which followed up 50,000 young men (when they entered for military service) and found a strong 'dose response' relationship. ie: The more often you'd smoked dope (before the age of 18), the higher the chance that you'd develop schizophrenia.

Yes, we all know that it doesn't mean automatically that it causes schizophrenia. There are some studies which seem to show that people are using it to self-medicate.


If we want to tell our kids that certain drugs are "bad," we should at least do it with accurate, factual information

Agreed. I've done my bit by collecting the references above to add to the one you listed.

So, in conclusion, the evidence seems to indicate that, at the very least, it 'make you stupid'.

A scientifically accurate public health warning would have the message: "Dope probably won't kill you. But it is likely to harm your memory, learning, thinking and problem solving skills"

Oddly enough, that is almost identical to the anti-dope ad I saw last night: "Dope probably won't kill you. But it will turn you into a d!ckhead." (Yes, that's an actual quote from the ad. Clearly we have a better class of public health ad here, compared to the USA)

Mac

Opty
10-04-2006, 02:17 AM
You seem to have a heated agenda here that my original post didn't intend to address.

People list many reasons why pot is bad for you and why you shouldn't smoke it. One of those I've heard is that "pot smoke is just as bad as cigarette smoke." So, I posted this article because it is both recent and offers scientific data which refutes such a claim.

If you want to make this into a "I don't care what you say, Pot is bad!" thread (which is what I figured would happen eventually), that's fine. Granted, the argument you're presenting seems to be a bit of a red-herring.

However, if you're going to make your point (which, is scientifically weak), at least quote more than one source for your point(s), and try to make them at least a little less than 10 years old.

MattW
10-04-2006, 02:41 AM
How about all of the proven bad things that are still legal? Booze and cigarettes come to mind.

Marijauna was outlawed because of the stigma attached to it by a racist government. It was associated with Mexican immigrants and black jazz culture, and the fear that it would corrupt the youth (especially white women).

Mac H.
10-04-2006, 02:54 AM
If you want to make this into a "I don't care what you say, Pot is bad!" thread (which is what I figured would happen eventually), that's fine
But I do care what you say.

You said that it doesn't cause lung cancer like tobacco.
And you say that it isn't AS BAD as alcohol, but don't disagree that it is bad for you.

So why should me making a point (that it is still bad for you) be off topic? It's like if someone pointed out that drinking diesel fuel didn't cause cancer. Would it be out of line for me to respond that it still isn't a good idea to drink diesel fuel?

-
Sorry that I didn't give you a complete list of recent studies.

Nadia Solowij has published several studies over the last decade on the long term affects of smoking dope. These are rigorous enough to be published in 'Journal of the American Medical Association' & 'Neurology'

I haven't religiously read science journals for a few years now, but still read 'New Scientist', which always gives a good summary of any new cannabis related studies. Even the obscure ones are mentioned - like experiments using synthetically produced cannabinoids to treat people with inflamed bowels.

Having said that, I can't think of any recent major studies which indicated that dope DIDN'T have negative effects of cognitive ability.

Sure, it is difficult to eliminate the 'Idiots tend to use cannabis' effect (you can't do a proper double blind study for obvious reasons!) but the fact that longer use means lower cognitive ability surely would have to imply more than that - it would mean that the stupider you are, the longer you use cannabis for. This would surely seem unlikely to be dominant over all the social pressures, etc?

Looking forward to seeing the references...

Mac

Mac H.
10-04-2006, 03:01 AM
How about all of the proven bad things that are still legal? Booze and cigarettes come to mind.Absolutely. Criminalising Marijuana use is really, really stupid. But can we agree that it is bad for you?


Marijauna was outlawed because of the stigma attached to it by a racist government. It was associated with Mexican immigrants and black jazz culture, and the fear that it would corrupt the youth (especially white women).Umm - while that make sense in the USA, are you seriously claiming that it is true for the other 190 odd countries?

Did Indonesia outlaw it because of it being associated with Mexican immigrants and black jazz !!??

Surely the fact that it is outlawed in many other countries (well before the USA had any real world influence) indicates that there is more to the story?

Mac

Opty
10-04-2006, 03:07 AM
But I do care what you say.

You said that it doesn't cause lung cancer like tobacco.
And you say that it isn't AS BAD as alcohol, but don't disagree that it is bad for you.

So why should me making a point (that it is still bad for you) be off topic? It's like if someone pointed out that drinking diesel fuel didn't cause cancer. Would it be out of line for me to respond that it still isn't a good idea to drink diesel fuel?

Because you presented your point in such a way as to imply that I was being somehow disingenuous or that my post was riddled with pretext, when you said:

You forgot to include this rather important snippet in your quote

And then further implied that I was "hiding other facts" when you said:

I'm confused here. Your aim is to spread the facts and dispel the myths.

Great. So why are you mentioning certain facts ("doesn't contribute to lung cancer") but not others ?

Sure, the media and your government may be biased and ignore certain facts, but surely it is just as reprehensible to respond by doing the same, but in the opposite direction ?

As I had already mentioned, my original post had one purpose, and one purpose only: "My post and the article are [specifically] about the cancer risk..."

For you to imply that I was purposely not mentioning facts (implying that my intention was to deceive) which had absolutely nothing to do with the specific information contained within the article is rather insulting, if not baleful.

I was addressing one specific issue. If you wanted to discuss others, that is fine. But, elliciting a discussion of those other issues can be done without calling my character into question by implying that I have some sort of hidden agenda.

Mac H.
10-04-2006, 03:49 AM
For you to imply that I was purposely not mentioning facts (implying that my intention was to deceive) which had absolutely nothing to do with the specific information contained within the article is rather insulting, if not baleful.
Apologies if it came across like that.

However, to be pedantic, the extra info that I posted DID come exactly from the original article. I just get worried if I see a quote from an article about "Drinking Diesel fuel doesn't cause cancer" which also doesn't mention another point made in the article - that drinking diesel fuel has other bad effects so it really isn't recommended.


I was addressing one specific issue. If you wanted to discuss others, that is fine.
Hang on - my second post in this thread was to respond to posts in the thread ahead of mine. In particular it was to refute the idea that "It's more likely (based on scientific evidence) that morons are attracted to pot than it is that pot creates morons"


Calling my character into question by implying that I have some sort of hidden agenda.Woah - I've never thought that having an unspoken agenda in a conversation as underhanded - it is just a natural part of conversation. We all have agendas. We may want to promote world peace, or promote logical thinking. We don't need to announce them at the start of each conversation. I'm just assuming that you'll see my agenda as the conversation progresses, and vice versa.

Good luck,

Opty
10-04-2006, 04:07 AM
I just get worried if I see a quote from an article about "Drinking Diesel fuel doesn't cause cancer" which also doesn't mention another point made in the article - that drinking diesel fuel has other bad effects so it really isn't recommended.

I wasn't trying to mislead anyone by only quoting a portion of the article. I did that to entice people into reading the entire article which I linked below it.

Posting the entire article would've been a copyright violation.


Hang on - my second post in this thread was to respond to posts in the thread ahead of mine. In particular it was to refute the idea that "It's more likely (based on scientific evidence) that morons are attracted to pot than it is that pot creates morons"

Okay, but nothing you posted refuted that specific point. All it shows is that HEAVY pot ABUSE can contribute to synaptic degeneration.

I would never dispute that.

However, the argument that many on the "anti-pot" side of the aisle try to extrapolate from most related scientific data is that ANY pot consumption causes neurological damage.

That's simply not true and isn't supported by most widely accepted research.

Heavy abuse of pot can cause brain damage, some of it may be irreversible. However, heavy abuse of ANY substance - from pot, to alcohol, to Big Macs, to chocolate cake - can be deleterious to one's health. Just like the occasional glass of wine with dinner won't hurt the average person (unless, of course, you're an alcoholic), the occasional joint won't really hurt you, either. Doesn't mean I'm advocating it. I'd never smoke pot. Just means I'm being accurate. Don't even get me started on the misinformation that abounds regarding MDMA (Ecstacy).

The majority of studies involving/showing the harmful effects of pot are focused on the damage done to heavy abusers, not occasional tokers.

The amount of neurological damage, permanent or otherwise, from one joint is probably comparable to the neurological damage from a few shots of vodka.

Occasional, infrequent, recreational pot use causes no discernable, permanent neurological/psychological damage. Heavy abuse (as with almost any substance), though, can be damaging.

nicegrrl
10-04-2006, 04:21 AM
I have to agree that occaisional or rare use of marijuana has no consequential effects. And pot isnt paticularly addictive for most people.

Bravo
10-04-2006, 04:22 AM
spork can certainly make a lot of money if he wrote out prescriptions for it though.

Mac H.
10-04-2006, 04:49 PM
Dr Spork:"It's more likely (based on scientific evidence) that morons are attracted to pot than it is that pot creates morons"

Mac: (Reference to study showing that heavy pot use makes people stupid)

Dr Spork: "Okay, but nothing you posted refuted that specific point. All it shows is that HEAVY pot ABUSE can contribute to synaptic degeneration."
Sheesh. OK.

While we haven't fully disproved the idea that "It's more likely that morons are attracted to pot than it is that pot creates morons", we are both agreed that heavy pot use DOES create morons.

But what about low doses ?

There was a nice meta-study done to check the effects of low doses.

There are a pile of disclaimers about dodgy data, but the results were ...

* In 6 out of 8 neurological tests there were no significant losses
* The 2 out of 8 tests where 'low use' pot users were statistically significantly worse on were 'learning' & 'forgetting'.

In other words they had trouble learning, and had trouble remembering.

I'd hazard a very non-scientific guess and assume that because the results were so focussed on specific abilities, it is a real affect rather than simply a 'that type of person is more likely to take pot'.

I can understand the theory that 'stupid people are more likely to take pot', but can't really see that 'people who are otherwise smart but do worse on memory tests are more likely to take pot'.

The loss in memory ability may be small enough not to worry the person taking pot. It wasn't huge, after all.

So ...

Original statement: "It's more likely that morons are attracted to pot than it is that pot creates morons"

Results of a quick literature search :
1. Heavy pot use creates morons
2. Low pot use over long periods simply gives a measurable loss in memory ability.

Mac

Opty
10-05-2006, 05:06 AM
But what about low doses ?

There was a nice meta-study done to check the effects of low doses.

There are a pile of disclaimers about dodgy data, but the results were ...

* In 6 out of 8 neurological tests there were no significant losses
* The 2 out of 8 tests where 'low use' pot users were statistically significantly worse on were 'learning' & 'forgetting'.

In other words they had trouble learning, and had trouble remembering.

Were these tests measuring the effects of "intoxication" or the long-term effects of marijuana use (post-intoxication, implying permanent neurological damage)? That would be very important to the discussion, especially considering that only 2 out of the 8 tests found any significant impairments.



2. Low pot use over long periods simply gives a measurable loss in memory ability.

I'd be interested in reading the studies which show this condition to be permanent.

Primarily, THC binds to CB (cannabinoid) receptors where it exhibits a complex pharmacologic effect on numerous parts of the CNS. The CB receptor is an endogenous anadamide receptor (anadamide is the brain's THC, and produces the same effect, which is why anadamide is a controlled substance even though it's in everyone's brain).

Cannabinoids exert a pharmacolgic effect on virtually every known neurotransmitter system, and their effects on the opioid, sertonin, dopamine and GABA and cholinergic systems are probably responsible for the majority of the central effects.

As a statement of fact, cannabinoids cannot kill neurons. Period. There is not one single study which shows that marijuana is a neurotoxin. Cannabinoids have even been shown in numerous university studies to be neuroprotective and antioxidant. Cannabinoids also have been shown to experimentally induce apoptosis in tumor cells.

So, as I said, I'd be interested in reading a credible study which shows that marijuana in low doses causes permanent neurological damage.

Mac H.
10-05-2006, 06:43 AM
Were these tests measuring the effects of "intoxication" or the long-term effects of marijuana use (post-intoxication, implying permanent neurological damage)?They confirmed using daily urine samples that they'd been drug free for the previous 28 days. (I'm relying on my memory here, which has been letting me down lately)

Surely we've already agreed that heavy dope use does cause permanent damage ? So why would it be so unexpected that there is also a lesser affect at lesser doses?


As a statement of fact, cannabinoids cannot kill neurons. Period. There is not one single study which shows that marijuana is a neurotoxin.
Hang on - is this right? Have you actually checked this ?

30 seconds googling (try "THC neurotoxicity") gives examples of literature reviews on this very subject.

For example:

http://sulcus.berkeley.edu/mcb/165_001/papers/manuscripts/_956.html



A recent study by Chan et al. (1998) showed the neurotoxicity of THC on cultured rat hippocampal neurons and slices. THC not only caused the shrinkage of cell bodies and nuclei of neurons, but also caused genomic DNA strands to break. Neuronal toxicity was found even with low doses of 0.5 (M, which is comparable to normal human consumption (Chiang and Barnett 1984), and that the rate of cell death increased with THC concentration, up to 20 (M

....

It should be addressed that although Chan et al.'s conclusion is valid, this experiment is done on hippocampal neurons of rats in vitro. It should be questioned whether it can be extrapolated to human hippocampal neurons in vivo. Even if this idea were accepted, it needs to still be determined whether permanent memory loss would occur due to the neuronal death of these cells by THC, although it would be a viable argument.

Clearly the statement "There is not one single study which shows that marijuana is a neurotoxin." is false.

However, there is also an interesting link with another study ...

One experiment by Drew et al. (1980) uses a test battery consisting of a series of psychometric tests including Babock Story Recall, Digit Span, Paired-Associate Learning, and Murdock Retention Test.

..
The interesting portion of this study compares the performance of marijuana intoxicated subjects with hippocampal brain damaged patients (temporal lobe). The result is that the two groups perform very similarly on the test battery. Drew et al. conclude that being under the influence of marijuana is similar to creating a lesion on the hippocampus with recent memory functions. They support the idea that since the hippocampus is critical in the formation of memories, having it temporarily "lesioned" while intoxicated can explain the deficit of memory function.

In can also be hypothesized that in light of the neurotoxicity finding by Chan et al., the long term cognitive effect of THC induced hippocampal cell death may be similar to the performance of the marijuana-intoxicated group and the hippocampal lesioned group on recent memory functions.

A fascinating subject.



So, as I said, I'd be interested in reading a credible study which shows that marijuana in low doses causes permanent neurological damage.I'll see if I can dig it up. However, I'm still waiting for the one that you quoted which showed that "It's more likely (based on scientific evidence) that morons are attracted to pot than it is that pot creates morons" (Insert winky face.)

Mac

Opty
10-05-2006, 07:20 AM
They confirmed using daily urine samples that they'd been drug free for the previous 28 days. (I'm relying on my memory here, which has been letting me down lately)
Perhaps from pot?


Surely we've already agreed that heavy dope use does cause permanent damage ? So why would it be so unexpected that there is also a lesser affect at lesser doses?

Well...yes and no. I've seen data that shows that heavy, long term abuse correlates with some memory impairment. However, I'm not fully convinced that it is due totally to marijuana. So, I usually err on the side of caution with my opinion and just say that heavy use "causes" brain damage. That may be totally wrong, but it's been a while since I've researched this. I'm going to leave my opinion open to revision as more persuasive/conclusive information becomes available to me.


30 seconds googling (try "THC neurotoxicity") gives examples of literature reviews on this very subject.

Well, I admit that I overgeneralized and overstated my original statement. I should've said, there is not one single study which shows that smoking marijuana by humans causes neurotoxicity.

If we go by your posted example...

Sure, if you take the THC out of marijuana, titrate it to its purest form, and inject it directly into a petri dish of a very small slice of rat hippocampal cell tissue, in a dosage concentration that is not physically possible for a rat to ingest under normal life circumstances, then yes, I suppose it can cause some damage in rats.

If we interpolate this data for humans (considering that no study such as this has ever been done on humans), we can conclude that, yes, THC might be toxic to humans if they were to consume it in the form of eating marijuana (not smoking it) that has at least a 5% THC concentration (most marijuana has 0.5% to roughly 3% THC) in the amount of 3 to 4 pounds all at one time. (However, considering that hippocampal CB1 receptor structure in humans is vastly different than that of rats, I guess we can't conclusively even say that much.)

Considering that it is physically impossible for a human to consume this much marijuana, I'm not too worried about it ever happening. Thus, the practical neurotoxicity of marijuana on humans is statistically close to non-existent.


In can also be hypothesized that in light of the neurotoxicity finding by Chan et al., the long term cognitive effect of THC induced hippocampal cell death may be similar to the performance of the marijuana-intoxicated group and the hippocampal lesioned group on recent memory functions.

This is an extremely bullsh-t conclusion/hypothesis to draw, considering that it is impossible to prove the THC neurotoxicity that Chan is guessing "might" happen in human hippocampal cells if they were to ever be exposed to levels of THC physically impossible for a person to ever consume.

Got anything else? ;)

Bravo
10-05-2006, 07:32 AM
this thread has convinced me to go get high.

then im gonna try some shrooms. i hear those arent as bad as ppl say either (http://www.cbc.ca/health/story/2006/07/10/mushroom-psychedelic.html).

Mac H.
10-05-2006, 07:46 AM
I should've said, there is not one single study which shows that smoking marijuana by humans causes neurotoxicity.Is that a sensible statement?

How could such a study be done?

The only 'real' study would be to get a group of non-pot smokers, and make half a control group, and make the others smoke pot.

Then get them to stop, wait a few years & biopsy their brains. Including the poor control group.

Clearly, this research would never be done in the real world (post Nazi era) so using the non-existance of a study isn't an argument either way !

However, there have been some humane variations - simple MRI scans to see if there are visible difference between ex-pot users (even low dose ones) and a control group.

An odd study which did something like that is discussed in the last link I gave. You can guess the result. (It was odd because of the way the selected the group of people to test)


This is an extremely bullsh-t conclusion/hypothesis to draw, considering that it is impossible to prove the THC neurotoxicity that Chan is guessing "might" happen in human hippocampal cells if they were to ever be exposed to levels of THC physically impossible for a person to ever consume.Indeed, there are a lot of 'ifs' in the hypothesis, which they didn't try to hide.

However, it is still interesting that:
a. The memory impairment that pot users suffer is similar to memory impairment caused by lesions in the hippocampus, rather than lesions elsewhere in the brain.
b. In vitro rat studies show that the neurons of the hippocampus suffer from the neurotoxic affects of THC (an active ingredient in pot) more than other neurons in the brain

Sure - you are right. It could just be a coincidence.

Interestingly, there may be an approach that might help - just get the rats to smoke - then you can at least eliminate the 'does it still apply if the THC is smoked?' question.

A fascinating area. Looking forward to seeing more on it ..

Mac

Mac H.
10-05-2006, 07:48 AM
this thread has convinced me to go get high.

then im gonna try some shrooms.Before you do that, run to the shops and buy the latest edition (30-September-2006) of New Scientist.

They have a great article on legal ways to get high.

Mac

Bravo
10-05-2006, 07:51 AM
whats the verdict on occasional coke use?

that's a classier drug.

Opty
10-05-2006, 08:09 AM
Is that a sensible statement?
Yes.


How could such a study be done?
It could possibly be inferred from a combination of functional MRI (fMRI) and PET studies.


An odd study which did something like that is discussed in the last link I gave. You can guess the result. (It was odd because of the way the selected the group of people to test)
That study compared lesioned patients to intoxicated participants. That proves nothing about the long term, non-intoxication effects.


However, it is still interesting that:
a. The memory impairment that pot users suffer is similar to memory impairment caused by lesions in the hippocampus, rather than lesions elsewhere in the brain.

Again, that study compared lesioned patients to intoxicated participants. It did not study long term effects, only effects of marijuana intoxication. So, your claim about "pot users" is a bit misleading, as it leaves out that the studies focused on marijuana intoxication effects, not long term, residual effects.


b. In vitro rat studies show that the neurons of the hippocampus suffer from the neurotoxic affects of THC (an active ingredient in pot) more than other neurons in the brain

Yes, it's amazing the things which effect slices of rat brain cells in a petri dish.

There's a huge difference between using cultured cells (which are cut off from the body's own built in protections) and studying the effects of THC in vivo.

As my friend Joe (a neuroscientist and expert psychopharmacologist whom I consult on matters like this) has said: "This is what we call "junk science". It's science that purports to replicate "real world" conditions but does no such thing." According to him (and, I trust his expertise over my own research skills), there has never been a single IN VIVO study which showed THC neurotoxicity, and this is all that counts. You can bathe neurons in almost any chemical, and without a supply of blood and nutrients, they will die.

A chemical cannot be both neuroprotective and neurotoxic, it's impossible. There are loads of in vitro and in vivo studies showing that THC is neuroprotective and only a handful of studies which show neurotoxicity. Unlike drugs such as methamphetamine (which actually IS a neurotoxin at high doses), there are no in vivo studies showing neuronal destruction from THC.

It is entirely possible, I suppose. But, that has never been proven in vivo and, like I said, that's the only type of study that would really count (i.e. prove anything). So, while I'm not ruling out the possibility that it may be shown in in vivo research one day, up to this point it hasn't been, so I remain skeptical.

Also, those studies you cited show that THC seems to affect the hippocampal cells much more than other cells of the brain with comparable numbers of CB1 receptor cells. Why were those cells not affected by THC in the same way?


Interestingly, there may be an approach that might help - just get the rats to smoke - then you can at least eliminate the 'does it still apply if the THC is smoked?' question.
Who asked that question?

Soccer Mom
10-05-2006, 08:10 AM
I'll just stick to abusing coffee and chocolate thanks.

nicegrrl
10-05-2006, 02:54 PM
Surely we've already agreed that heavy dope use does cause permanent damage ? So why would it be so unexpected that there is also a lesser affect at lesser doses?


It doesnt work that way for alcohol or sugar either.

Mac H.
10-06-2006, 07:34 AM
That study compared lesioned patients to intoxicated participants. That proves nothing about the long term, non-intoxication effects.

Again, that study compared lesioned patients to intoxicated participants. It did not study long term effects, only effects of marijuana intoxication. So, your claim about "pot users" is a bit misleading, as it leaves out that the studies focused on marijuana intoxication effects, not long term, residual effects.I'm starting to suspect that you aren't reading what you are replying to.

To quote the reference I gave: "It should be emphasized that the images taken of the subjects were not taken while intoxicated"

Sheesh. And I'm sorry that your friend Joe feels that the study was 'junk science'. He should complain to the 'Journal of Neuroscience', which is obviously a terribly unscientific journal. Yes, it would be 'junk science' for me to argue that 'This is proof that dope is bad for you'. However, I wasn't saying that. I brought it up SOLELY because you argued that 'no study had ever shown it to be neurotoxic' !!! (And once I brought it up, I pointed out the cool result that the exact same part of the brain that was damaged by the dope was linked to the functionality that seems to be missing in ex-dope users)

You replied that it didn't count because it wasn't on humans. I replied that they don't do neurotoxicity studies on humans for obvious reasons.

You replied that you would accept a combination of functional MRI studies, etc, on non-intoxicated people instead.

OK . Here's one of the studies for your combination :

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16585053&query_hl=2&itool=pubmed_docsum

To quote the study:
"Despite similar task and cognitive test performance compared with control subjects, active and abstinent marijuana users showed decreased activation in the right prefrontal, medial and dorsal parietal, and medial cerebellar regions, but greater activation in various frontal, parietal and occipital brain regions during the visual-attention tasks (all with P < or = 0.001, corrected, cluster level). However, the BOLD signals in the right frontal and medial cerebellar regions normalized with duration of abstinence in the abstinent users.

...

The greater activation in the active compared with abstinent marijuana users demonstrates a neuroadaptive state in the setting of active marijuana use, while the long-term chronic effect of marijuana on the altered brain network may be reversible with prolonged abstinence."

(My emphasis)
I know that more, larger and longer studies would need to be done to give a
definitive answer. However, the dispute isn't whether there is long-term effects on the brain - the uncertainty is whether prolonged abstinence may eventually allow the brain to fully recover.

I'm not particularly arguing that it is neurotoxic - I wasn't the one who brought up that subject. I only replied to the clearly wrong statement that 'no study have ever found it to be neurotoxic'.

Mac

Mac H.
10-06-2006, 07:39 AM
It doesnt work that way for alcohol or sugar either.Ah yes. I wasn't arguing that it would automatically be that way. Clearly it doesn't work for temperature either.

However, I'm just arguing that it isn't surprising. Given that a large amount of of substance 'X' causes large memory problems, it simply isn't suprising if someone does a study and concludes that small amounts of 'X' causes small memory problems !

I just find the controversy amusing. The results are unsuprising.

Mac

nicegrrl
10-06-2006, 03:21 PM
Organic bodies are pretty resilient. They either adjust or reset after something brings on a change. Generally something has to be pretty severe to cause permanent problems. Probablyt, a cigarette once a week wouldnt affect most people in the long term. And if they quit, the damage would be recovered quickly.