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  Heavy Marijuana Use Shrinks Brain Parts - Study
Posted by CN Staff on June 02, 2008 at 14:51:24 PT
By Reuters 
Source: Reuters 

cannabis Washington, DC -- Long-term heavy use of marijuana may cause two important brain structures to shrink, Australian researchers said on Monday.

Brain scans showed the hippocampus and amygdala were smaller in men who were heavy marijuana users compared to nonusers, the researchers said. The men had smoked at least five marijuana cigarettes daily for on average 20 years.

The hippocampus regulates memory and emotion, while the amygdala plays a critical role in fear and aggression.

The study, published in the American Medical Association's journal Archives of General Psychiatry, also found the heavy cannabis users earned lower scores than the nonusers in a verbal learning task -- trying to recall a list of 15 words.

The marijuana users were more likely to exhibit mild signs of psychotic disorders, but not enough to be formally diagnosed with any such disorder, the researchers said.

"These findings challenge the widespread perception of cannabis as having limited or no harmful effects on (the) brain and behavior," said Murat Yucel of ORYGEN Research Centre and the University of Melbourne, who led the study.

"Like with most things, some people will experience greater problems associated with cannabis use than others," Yucel said in an e-mail. "Our findings suggest that everyone is vulnerable to potential changes in the brain, some memory problems and psychiatric symptoms if they use heavily enough and for long enough."

Among the 15 heavy marijuana users in the study, the hippocampus volume was 12 percent less and the amygdala volume was 7 percent less than in 16 men who were not marijuana users, the researchers said.

The researchers acknowledged that the study did not prove it was the marijuana and not some other factor that triggered these brain differences. But Yucel said the findings certainly suggested marijuana was the cause.

"Stoned" For 20 Years

While about half of the marijuana users reported experiencing some form of paranoia and social withdrawal, only one of the nonusers reported such symptoms, Yucel said.

The heavy marijuana users, average age 40, said they had used other illicit drugs less than 10 times, the researchers said.

A U.S. group supporting legal sales and regulation of marijuana took issue with the findings, particularly because they were based on men who were such heavy, long-term users.

"These were people who were essentially stoned all day every day for 20 years," Marijuana Policy Project spokesman Bruce Mirken said by e-mail. "This study says nothing about moderate or occasional users, who are the vast majority -- and the (study) even acknowledges this."

"The documented damage caused by comparably heavy use of alcohol or tobacco is just off-the-charts more serious, and you don't need high-tech scans to find it," Mirken added.

Yucel said the researchers have begun new research on the effects of both short-term and long-term and moderate and heavy use of marijuana. (Editing by Maggie Fox)

Source: Reuters (Wire)
Published: June 2, 2008
Copyright: 2008 Reuters Limited

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Comment #10 posted by FoM on June 11, 2008 at 14:37:19 PT
Related Article From AlterNet
Smoking Pot All Day, Every Day Might Not Be Good For You

By Paul Armentano, NORML

June 10, 2008


[ Post Comment ]

Comment #9 posted by Storm Crow on June 02, 2008 at 17:31:41 PT
I'll "see" your study, and raise ya two more!
Marijuana Promotes Neuron Growth

Marijuana May Spur New Brain Cells

*Cannabinoids promote embryonic and adult hippocampus neurogenesis

[ Post Comment ]

Comment #8 posted by Sam Adams on June 02, 2008 at 16:33:10 PT
what a crock
give me a break. Thanks AMA! nice hit job for your Big Pharma friends.

we'll file this piece of junk science and journalistic trash right there next to "makes young men grow breasts"

it does prevent a novel way for the cops to find the stoners though - just give there forehead a firm knock with your knuckles & see if there's an echo. what a joke

[ Post Comment ]

Comment #7 posted by Hope on June 02, 2008 at 16:26:32 PT
It's funny that these type of "researchers"
since prohibition of cannabis began like to focus on the shrinking brains of cannabis users.

We've heard this brain shrinking rigmarole for years and years and years. They couch it a little differently every time... but it's the same thing... brain shrinking. It's not true now, and it never was and I wish they'd quit opening the same stinking can of dead worms and sticking it under our noses over and over again, year after year.

Anyone ever wonder what baloney every day for twenty years might do to the brain?

They just want to keep bringing as much harm and whipping and misery to the people who use cannabis, as much, and for as long, as they can get away with it... which, they hope, is forever.

That's all there is to it. They're sick puppies.

[ Post Comment ]

Comment #6 posted by HempWorld on June 02, 2008 at 16:16:32 PT
Yeah, right ...
1. This is 'news' from Reuters 2. Alcohol shrinks really your brain (but they don't say that) for anyone reading this with some time on their hands, please google brain shrinking on alcohol and post it here, thanks! 3. Better to have a brain on cannabis without cancer than a shrunk brain on alcohol with cancer!

[ Post Comment ]
Comment #5 posted by Hope on June 02, 2008 at 16:16:21 PT
Of course. Of course. Of course.
"The researchers acknowledged that the study did not prove it was the marijuana and not some other factor that triggered these brain differences."

But, of course, as usual, that won't keep crap like this "research" from being all over the media and shrinking minds set up for it all over the world.

Why do people's ears get larger as they age? Is their head shrinking instead? It must be the marijuana.

[ Post Comment ]

Comment #4 posted by potpal on June 02, 2008 at 16:14:42 PT
prohibitionist fear
In light of this new propaganda, with the little brain they have to start out with, a few years of smoking pot and their brain may disappear all together!

[ Post Comment ]
Comment #3 posted by Hope on June 02, 2008 at 16:08:11 PT
I wish they'd just give humanity and the Earth a break and stop coming up with all these lame excuses as to why they should be allowed to keep on killing, torturing, and abusing cannabis and cannabis users all over the world.

It's stone cold, patently obvious to anyone with any working brain cells that the prohibitionists and their policies are hurting people far worse than cannabis use ever could.

That's a FACT!

[ Post Comment ]

Comment #2 posted by OverwhelmSam on June 02, 2008 at 16:03:59 PT
Five Joints A Day for Twenty Years!
So what. They just don't get it. It's my body and I have a right to shrink my various body parts if I so chose. LOL

[ Post Comment ]
Comment #1 posted by charmed quark on June 02, 2008 at 15:24:24 PT
Heavens! Shrinking body parts
""These findings challenge the widespread perception of cannabis as having limited or no harmful effects on (the) brain and behavior," said Murat Yucel of ORYGEN Research Centre and the University of Melbourne, who led the study."

Sounds a little desperate to me.

Too bad they only found shrinkage in the brain. Imagine the hay they could make if it was another male body part that shrank due to heavy cannabis use:-)

Obviously, there's nothing typical about someone who is heavily stoned for 20 years ( hey, I'm not talking about anyone here!) You can almost always find differences in any subpopulation that is out 4 or 5 sigma from the norm.

Could it not be that whatever underlying tendency/disorder that led these men into their lifestyle also accounts for the physiological and/or psychological differences they found between these men and the average population? Or maybe something in the lifestyle itself that is associated with being stoned so long ( all those munchies? Too much TV?). Just wondering....

[ Post Comment ]

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