Marijuana 'shrinks the brain'

[freddie]

Marijuana 'shrinks the brain'

Tamara McLean | June 3, 2008 - 11:11AM

 

CHICAGO - Heavy marijuana use over many years appears to shrink parts of the brain that control emotion and memory, an Australian study shows.

 

Brain scans on 15 men who smoked at least five joints a day for more than a decade show for the first time that they have structural brain abnormalities not seen in non-smokers.

 

The researchers from the University of Melbourne say their findings should settle the historic controversy over the long-term effects of cannabis use with solid proof of the damage it causes.

 

"These findings challenge the widespread perception of cannabis as having limited or no consequences on the brain," said study leader Dr Murat Yucel, a clinical neuropsychologist at the Melbourne Neuropsychiatry Centre.

 

"Although modest use may not lead to significant neurotoxic effects, these results suggest that heavy daily use might indeed be toxic to human brain tissue."

 

The study, published in the US journal Archives of General Psychiatry, showed two important areas of the brain were smaller in long term smokers.

 

The hippocampus, thought to regulate emotion and memory, was 12 per cent smaller in volume and the amygdala, involved with fear and aggression, was reduced by seven per cent.

 

The smokers also were more likely to show mild signs of psychiatric disorders, but not enough to be formally diagnosed with one, Dr Yucel said.

 

The men also performed "significantly worse" in a memory test that involved trying to recall a list of 15 words.

 

He admitted the findings did not necessarily prove marijuana was responsible for the difference in brain volume but the findings strongly suggest this was the cause.

 

If this was the case, this indicated everyone was vulnerable to potential changes in the brain, some memory problems and psychiatric symptoms if they used heavily enough and for long enough, the researchers said.

 

The study involved men who were around the age of 40 and who had not taken other illicit drugs more than 10 times.

 

Another recent research review from the University of NSW showed that cannabis smokers had a 40 per cent increased risk of developing schizophrenia, and smoking daily drives the risk up two-fold. Other studies have linked the habit to gum disease and lung cancer.

 

Statistics show a third of Australians have smoked at least once in their life, with about 300,000 using daily.

 

AAP

http://www.brisbanetimes.com.au/news/life-...2258787544.html

 

More bad news folks.

i don't smoke anywhere near 5 joints a day but I used to.

 

http://www.webmd.com/brain/news/20080602/m...?src=RSS_PUBLIC

 

an earlier study:

 

http://www.webmd.com/mental-health/news/20...nt-damage-brain

 

Edit: just found this to confuse the issue. It shows the opposite:

http://bodo.gnn.tv/blogs/17618/Study_Shows...ain_Cell_Growth

http://www.world-science.net/othernews/051018_potfrm.htm

Edited June 3, 2008 by freddie

[brick]

Why do they keep trying to find fault with mj. Alcohol over time does more than just fuck up your liver, it messes more with the motor neural functions of you brain, fucks up family's, causes more road trauma etc etc and it is legal.

If they are trying to stop youngsters from smoking then stop being half arsed and ban tobacco as well and ban alcohol with it, oh yes thats right they found out prohibition doesn't work.

[Low_ryder]

He admitted the findings did not necessarily prove marijuana was responsible for the difference in brain volume

 

I know that mj is not beneficial when used chronically but i can not take tests like this seriously when they do not do it on a larger group with stricter restrictions.

 

I wish they would fund some research into the beneficial sides of mj but that is not likely to happen anytime soon.

 

Just my 2c

[snowboardin_stoner]

Brain scans on 15 men who smoked at least five joints a day for more than a decade show for the first time that they have structural brain abnormalities not seen in non-smokers.

 

 

 

15 seems like a pretty small test group...

[Al Fish]

“Brain scans on 15 men who smoked at least five joints a day for more than a decade...” Fucking cunts! Who supplied the joints? Was this some sort of government study?

 

“...heavy daily use might indeed be toxic to human brain tissue." Same as a lot of different religious and political beliefs. Take a good, hard look around at society and its politicians and then talk to me about 'toxic human brain tissue'.

 

“...the amygdala, involved with fear and aggression, was reduced by seven per cent.” Fuckin' Aye! What's wrong with that?

 

“The smokers also were more likely to show mild signs of psychiatric disorders, but not enough to be formally diagnosed with one.” Who doesn't show mild signs of psychiatric disorder? Where I come from most people are over-medicated and have significant psychiatric disorders. I smoke dope for health reasons – mental health reasons.

 

“The men also performed 'significantly worse' in a memory test that involved trying to recall a list of 15 words.” Can it get any vaguer? Did they have to remember the words for the duration of the test – “more than a decade”?

 

“He admitted the findings did not necessarily prove marijuana was responsible for the difference in brain volume...” Yeah that's right, isn't it, Arse-hole? You bloody trumped up excuse for a scientist. You're not even a Doctor's arse-wipe!

 

“If this was the case, this indicated everyone was vulnerable to potential changes in the brain, some memory problems and psychiatric symptoms if they used heavily enough and for long enough.”

I should be so lucky! Five joints a day for more than a decade!

 

“Another recent research review from the University of NSW showed that cannabis smokers had a 40 per cent increased risk of developing schizophrenia, and smoking daily drives the risk up two-fold.” Does that mean an 80% chance?

 

“Statistics show a third of Australians have smoked at least once in their life, with about 300,000 using daily.” How do they know how many smoke daily? 300, 000 seems a bit low. A lot of people where I live smoke daily – but I don't know 'em.

[brick]

15 seems like a pretty small test group...

 

Maybe the others forgot to turn up!!!!!!!!!!!!!

[mull]

Oh man this thread gave me a giggle... tears even.. cheers uni of melb

 

Please forgive my somewhat barren of logic thought process... product of severe brain shrinkage no doubt about it

 

But why...

 

Were there not... um..

 

40% of those 15 blokes who turned skitzo

 

Whose telling pork pies now

[tony2wheelsgood]

... and this from the US which contradicts it.

 

A spliff test for science

 

It's the oldest but most important scientific question when two phenomena appear related: does one cause the other, vice versa, or is the apparent relationship pure coincidence? The question came up again this week when an Australian study demonstrated that 15 men who had all smoked marijuana heavily for at least 10 years had shrunken brain structures compared to those in non-users.

 

So was it the cannabis that on average shrank their hippocampuses by 12% and their amygdalas by 7%? Or were these same regions small to start with in these men, and if so, was it something that played a part in their strong liking for cannabis?

 

Certainly, both these regions are heavily affected by cannabis because they are both unusually rich in molecular receptors for delta-9-tetrahydrocannibol (THC), the psychoactive component in weed. The hippocampus is vital for storing memories and for the perception of time, and marijuana is known to affect both. Likewise, the amygdala is the brain's "fear" centre, and plays a key role in whether we react aggressively to events. Again, this fits with the observation that cannabis users sometimes develop paranoia.

 

To come back to the Australia study, is it equally possible that such prolonged exposure to cannabis wears out and shrinks these cannabis-sensitive regions? Again, we're back to cause and effect.

 

The only way to resolve it once and for all (as pointed out by the Australian researchers themselves at the end of their paper) would be to have brain scans of people before and after they began smoking cannabis. That way, you could see whether these regions did actually shrink the more cannabis they were exposed to. Or whether some people with unusually small regions at the outset turned out to be more attracted to the weed.

 

Unfortunately, a study to find out by deliberately giving cannabis to volunteers then following them for many years to see if their brains shrank would be unethical. Ethical comparisons could only be done if scans had been performed randomly on a wide population of children and kept as a general resource for researchers. If any of the scanned children subsequently became heavy dope users, it would be easy to check back and monitor whether brain regions were changing size. But obtaining the scans would cost a huge amount of money without any guarantee that it would yield any findings of interest.

 

So for now, we simply don't know for sure whether cannabis is genuinely changing brain architecture. And the same dilemmas apply to study of all addictions. Which is why some researchers contacted by New Scientist cautioned against sensationalising the Australian results.

 

"You must be very careful looking at this paper in isolation," says Tim Williams, who studies addiction at the University of Bristol. "With this kind of study, you can't tease out cause and effect." Williams also pointed out that a study in 2005 of long-term cannabis users by researchers at Harvard Medical School found that there was no effect on the size of their hippocampuses. "I'm surprised the Australians found an effect where others haven't," he adds.

 

The take-home message is clear! Be cautious about concluding too much from addiction studies which might confuse cause and effect. Yes, it could be down to the drug, but equally, it could be down to your pre-existing brain architecture, and the effect of that on your personality.

 

Andy Coghlan, New Scientist reporter

source...ww.newscientist.com/blog/shortsharpscience/2008/06/spliff-test-for-science.html?DCMP=ILC-rhts&nsref=ts13_bar

[grace]

“Brain scans on 15 men who smoked at least five joints a day for more than a decade...” Fucking cunts! Who supplied the joints? Was this some sort of government study?

 

“...heavy daily use might indeed be toxic to human brain tissue." Same as a lot of different religious and political beliefs. Take a good, hard look around at society and its politicians and then talk to me about 'toxic human brain tissue'.

 

“...the amygdala, involved with fear and aggression, was reduced by seven per cent.” Fuckin' Aye! What's wrong with that?

 

“The smokers also were more likely to show mild signs of psychiatric disorders, but not enough to be formally diagnosed with one.” Who doesn't show mild signs of psychiatric disorder? Where I come from most people are over-medicated and have significant psychiatric disorders. I smoke dope for health reasons – mental health reasons.

 

“The men also performed 'significantly worse' in a memory test that involved trying to recall a list of 15 words.” Can it get any vaguer? Did they have to remember the words for the duration of the test – “more than a decade”?

 

“He admitted the findings did not necessarily prove marijuana was responsible for the difference in brain volume...” Yeah that's right, isn't it, Arse-hole? You bloody trumped up excuse for a scientist. You're not even a Doctor's arse-wipe!

 

“If this was the case, this indicated everyone was vulnerable to potential changes in the brain, some memory problems and psychiatric symptoms if they used heavily enough and for long enough.”

I should be so lucky! Five joints a day for more than a decade!

 

“Another recent research review from the University of NSW showed that cannabis smokers had a 40 per cent increased risk of developing schizophrenia, and smoking daily drives the risk up two-fold.” Does that mean an 80% chance?

 

“Statistics show a third of Australians have smoked at least once in their life, with about 300,000 using daily.” How do they know how many smoke daily? 300, 000 seems a bit low. A lot of people where I live smoke daily – but I don't know 'em.

 

lmao Al your commentary made this worth reading.

Edited June 4, 2008 by grace

[Nooby]

great thread m8's, even JJJ was pimping this report the other day sans relevant details of course, now I know why. ;-)