First, I'll put all my cards on the table; I believe at most, marijuana should be legal, and at the very least decriminalized.
If you paid attention to lately, for the first time since the issue has been tracked, the majority of Americans think that marijuana should be legal. (1)
The federal government and the Justice Department think otherwise. So, how do you change public opinion? Two steps: 1) Pay for a study. 2) Lie about the results.
Pay close attention to the headline:
"Casual pot use causes brain abnormalities in the youn: study." (2)
The opening sentence: (2)
"Young, casual marijuana smokers experience potentially harmful changes to their brains, with the drug altering regions of the mind related to motivation and emotion, researchers found."
Here is one of the loud mouth authors: "'This study raises a strong challenge to the idea that casual marijuana use isn't associated with bad consequences,' Breiter said." (3)
If you're at all familiar with this blog, you'll know that one thing to watch out for is quoting someone not affiliated with the research.
From another article
"'This study suggests that even light to moderate recreational marijuana use can cause changes in brain anatomy,' said Carl Lupica, PhD, who studies drug addiction at the National Institute on Drug Abuse, and was not involved with this study." (3)
So of course, this was a rigorous, well controlled, experimental study, which shows a causal link between marijuana use and a change in brain structure, as well has highlighting the negatives of these changes.
"The team of scientists compared the size, shape, and density of the nucleus accumbens and the amygdala — a brain region that plays a central role in emotion — in 20 marijuana users and 20 non-users. Each marijuana user was asked to estimate their drug consumption over a three-month period, including the number of days they smoked and the amount of the drug consumed each day. The scientists found that the more the marijuana users reported consuming, the greater the abnormalities in the nucleus accumbens and amygdala. The shape and density of both of these regions also differed between marijuana users and non-users." (3)
Nope, I was wrong. It was a correlation study. You wouldn't know that from the Yahoo! article (or any popular press article) by the use of the word "cause" in the lead title. Here's what we know from this study. The brains of a small sample of participants who casually smoke marijuana are different than non-smokers. Did marijuana cause these changes? maybe, maybe not. This study doesn't come close to showing that, but that doesn't stop people from saying it does.
When dealing with correlational research, always ask, what else could explain this result? One possibility may be that subjects' brains were different before they smoked marijuana. Maybe their nucleus accumbens or amygdala were already different and that made it more likely that they would use marijuana more than once. I'd be interested to know if the non-users ever smoked marijuana, since only a 3 month history was taken.
Fact is, this study doesn't address any of these possibilities. Instead, they take a non-generalizable study (very small sample size & limit age range) and turned it into anti-marijuana propaganda. So a big congratulations to the financial backers of this study: the National Institute on Drug Abuse, the Office of National Drug Control Policy, Counterdrug Technology Assessment Center, and the National Institute of Neurological Disorders and Stroke.
The sad part is, the media machine just regurgitates this garbage verbatim.