Heavy cannabis use linked to smaller brain parts.
June 5th 2008 22:33
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From NewScientist
Long-term, heavy cannabis users have been found to have smaller parts of the brain that relate to memory, the regulation of emotion and aggression, compared to non-users.
Murat Yücel at the University of Melbourne, Australia, and colleagues used high-resolution magnetic resonance imaging to compare the brains of 15 men who had smoked at least five joints daily for more than 10 years with those of non-drug users.
Aged brains
They found that volume of the hippocampus, which is involved in memory and regulating emotion, was on average 12% smaller in the cannabis users. The amygdala, which is involved in fear and aggression, was 7.1% smaller.
The cannabis users also scored significantly worse on short-term and long-term memory tests than the non-drug users.
"They are only about 39, but they were performing at the level of a 55- or 60-year-old," says Yücel.
They were also much more likely to suffer from psychotic-like symptoms, such as paranoia or social withdrawal. The smaller the size of their left hippocampus, the more severe the symptoms, though none of the patients warranted a diagnosis of a psychotic disorder.
Life changes?
The team found that the more cannabis the person used, the smaller the hippocampus and amygdala, and the more severe their psychotic symptoms. In studies in rats, cannabis has been shown to reduce the size of the hippocampus.
However, since the size of the hippocampus and amygdala in the men studied was not measured before the heavy consumption of cannabis began, it is not possible to say if the drug caused brain shrinkage or if these regions were already smaller.
Previous research on the brains of cannabis users has produced conflicting results, with some studies finding no changes to the volume of the hippocampus and amygdala. But most have looked at moderate rather than heavy use, and have used less accurate brain scanning techniques, Yücel says. He acknowledges that a limitation of the study is the small sample size.
Cannabis is the most commonly used illegal drug in the world, and about one in 10 people who try it go on to use it heavily. While modest use may not have neurotoxic effects, Yücel says, the work suggests that long-term, heavy use could have significant brain effects, which could impact on a user's life.
"Even though it's speculation to talk about mild or moderate users, one would expect dose-related change in the same brain areas," says Zerrin Atakan, a cannabis researcher at the Institute of Psychiatry in London. The more you use it, the more risky it is," she says.
Journal reference: Archives of General Psychiatry, vol 65, p 694
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Comment by tlcorbin
That is my take about the thought processes of most male pot smokers katyzzz, any female equivalent?
Raven
Comment by Louie
randomthoughts
Phil's Wellness Tips
Comment by katyzzz
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Louie, you've got it right honey.