WASHINGTON (Reuters) - 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. http://www.reuters.com/article/lifestyleMolt/idUSN0227147420080602?sp=true ---- I finished the article and then forgot what it was about
I had noticed a big drop in my short term memory, but I started playing Brain Age and other games of that sort and it really made me feel a lot sharper.
psychotic disorders..... that sunds like EXTREMELY heavey use for years. so just sober up for awhile every decade you'll be fine.
Haha what the fuck, it's the opposite widespread perception... And why did they only use 30 people? I'd like to see their methodology... So every single one of the subjects hadn't used illicit drugs more than 10 times? I call bullshit. At least he acknowledged this though
well I could believe the claim that they hadn't used other illicit drugs. Statistically, a very low percentage of marijuana users use any other drugs... I, for example, have never used any drugs besides marijuana and alcohol, those are my 2.
I find that statement quite false. I myself only smoke marijuana, but i have tried opium and zanex and other pills like that. But marijuana is said to be a gateway drug for more serious drugs like coke, crack, heroin, etc...Thats why i feel it is so hard to run tests for marijuana because its hard to find people who have smoked marijuana for 20 years and have not done anything else. Theres so many factors that could get throw into the tests. And I don't see how so many people are so negative with marijuana and yet they have never tried it?
Am I the only one that thinks 5 "marijuana cigarettes" a day for 20 years is a bit excessive? I think it was probably harder finding 15 of these subjects than 15 that haven't used more than 10 illicit drugs in their lives. Maybe it's just me...Also, to be honest, I'm not at all surprised that it affects the amygdala. I dare you to find one uptight asshole long-term pothead. I've only been smoking for a little over a year, on average 3-4 times a week...it has most definitely made me a more relaxed and open person in general.
I like this part. "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."
"5 marijuana cigarettes a day for 20 years" You guys would really be that surprised if this turned out to be true? Hell, after 20 years something has to happen.
It would be interesting to see if the areas mentioned returned to normal size after a period of abstinence from cannabis
I'm not discrediting this at all, but in studies like this there are so many variables that go unaccounted for.
The study is far too small to be reliable, and like the researchers themselves admitted, there is no way to conclusively determine if it is the marijuana or some other factor. Too much happens over the course of 20 years. People forget things, and they lie about things they're embarrassed about, etc. I'm not denying that marijuana affects the brain, but this tiny study basically provided no new information.
Personally I think this study was a waste of time. They should do more studies on moderate users as this is the majority of people using pot. I have smoked for years, sometimes heavily with other years not so heavily. I find it does my mind good as without it I would be a severly uptight asshole. TGT
exactly lol... i mean 5 joints a day for 20 years! thats a shit load of weed....its bound to effect ur brain cos ud be constantly stoned!
that report pissed me off.why you may ask becuse i live in australiea and that report was a headline that said weed shrinks your brain with heavy use. and up till then i was allowed to smoke weed in my room coz my mum let me then that report came in and she was yelling at me saying it makes you dume and all that shit it wasent till like a week or more later i was alowed to toke up again dame i hate that shit.alchaole causes like how many disorders and deaths and cancers then as soon as they dig up dirt on green witch isent even fully credited they go warning pepole about it leading to that miscomcepton weeds really bad for you. educate the public about legal drugs that are far worse and heavey use thats like with anything even too many viteman c tablets are bad for you so wtf dig up dirt on green as i say if its green its clean
I wanna call BS on all the guys who were smokers in the study. 5 cigarettes a day. Just try doing some of the math for that. Lets say the person rolls about .5g-1g per joint. That's 2.5-5 grams every day, which means it's 17.5-35 grams of bud every week. These guys are claiming to have consistently smoked well over half an ounce of weed every single week. They're smoking about quarter pound every month, and over 3 pounds every year for 20 years. I call BS because I doubt that someone had the funds, or steady enough of a supply to be smoking that much to themselves. Unless all these guys had thier own SOG grow setup for 20 years, I just don't think that what the study says is accurate in terms of how much the people were actually smoking.