Pubdate: Thu, 19 Feb 2015
Source: Boulder Weekly (CO)
Copyright: 2015 Boulder Weekly
Author: Leland Rucker


One of the main cannabis prohibition memes these days is based around 
some recent studies that suggest that cannabis use produces physical 
changes in the brain. This one really caught fire after The Journal 
of Neuroscience published research last spring from a 
Harvard/Northwestern report that scanned the brains of 40 students, 
half who used cannabis and half who didn't, and found volume, shape 
and density changes in two brain areas involved with emotion and motivation.

This got an enormous amount of press in publications no one should 
ever trust or read again like Time and USA Today, both of which seem 
to have become anti-marijuana mouthpieces. Media outlets greeted the 
Harvard study with the usual, scare-the-shit-outof-you headlines: USA 
Today came up with "Casual marijuana use linked to brain changes"; 
Time went even farther with "Recreational Pot Use Harmful to Young 
People's Brains."

Science being what it is, other researchers try to replicate results 
from other studies. To that end, Barbara J. Weiland, Rachel E. 
Thayer, Amithrupa Sabbineni, Angela D. Bryan and Kent Hutchison of 
the University of Colorado and Brendan E. Depue of the University of 
Kentucky looked at the brains of 158 individuals. They obtained 
high-resolution MRI scans from other studies and did their own 
investigations of differences in brain matter in the same regions.

Their report, "Daily Marijuana Use Is Not Associated with Brain 
Morphometric Measures in Adolescents or Adults," was published in the 
same Journal of Neuroscience this year. It found no statistically 
significant differences between daily users and nonusers on volume or 
shape in the brain regions of interest. "The results indicate that, 
when carefully controlling for alcohol use, gender, age and other 
variables, there is no association between marijuana use and standard 
volumetric or shape measurements of subcortical structures."

Whoa. Wait a minute. There are all these other studies. All those 
frightening headlines.

"Brain studies are difficult. When you look at the studies, one will 
find an effect in one region. The next group doesn't find an effect 
there but finds a different effect. If you take one region across all 
studies, there's no consistency," says Hutchison, a member of the 
research team and the CU Department of Psychology and Neuroscience.

As it turns out, the brain is malleable. Stress can change it. So can 
depression and meditation.

"Learning to play a music instrument changes the brain," Hutchison 
says. "It's possible that a person may have a slightly different 
brain in the first place. Ultimately, we won't be surprised to find 
out marijuana causes changes in the brain."

Hutchison says there is plenty of work yet to be done, but that so 
far, none of the studies have proven that cannabis causes the brain 
changes, especially when alcohol use is factored in. He hopes a 
multi-year U.S. National Institute on Drug Abuse study that will 
examine the brains of 10,000 kids from before they begin using 
marijuana, tobacco and alcohol and follow them through the years will 
answer some of those questions.

Speaking of government studies, a recent one comes up with some 
surprising results for one of the vexing problems of legalization: 
What is the correlation between using cannabis and getting behind the 
wheel of a car?

Colorado and most states that are legalizing treat cannabis 
intoxication much as they do alcohol. Here if you are found to have 
five nanograms of THC per milliliter of blood, you can be considered 
impaired if you're driving. Prohibition organizations scream bloody 
murder about stoned carnage on the highways while advocates argue 
that marijuana is less predictable and works far differently than 
alcohol, it's much more difficult to test and many medical and 
regular users would test positive for five nanograms, whether they 
were impaired or not.

So the Department of Transportation's National Highway Traffic Safety 
Administration's comprehensive study of 3,000 drivers involved in 
accidents over a 20-month period was eagerly anticipated. It found 
that fewer people are drinking alcohol and driving and more people 
are driving under the influence of cannabis. The number of drivers 
with evidence of marijuana in their system grew by nearly 50 percent 
from 2007 to 2014.

For alcohol, the study not surprisingly found the crash risk for 
drivers with a blood-alcohol content of 0.08 percent was twice that 
for sober drivers, and the danger went up dramatically from there - 
up to 12 times as high for a 0.15 reading.

But the cannabis finding was quite different: THC-positive drivers 
were 25 percent more likely to be in an accident, but once the 
researchers adjusted for confounding variables like age, gender, 
race, demographics and alcohol use, they could find no more risk of a 
cannabis user causing an accident than someone who was completely straight.

This is a pretty astounding result and admission, especially for a 
government agency. It's so interesting, in fact, that the official 
paper buries the info in favor of reporting that marijuana use is up 
rather than that its use was statistically not found to be a factor 
in accidents.

None of this is suggesting that people should be driving under the 
influence of marijuana - tests show it can impair driving ability. 
But what it does say is that perhaps the effects of cannabis are not 
as significant as those of alcohol, that cannabis doesn't work in the 
body like alcohol and that we need better ways to study and approach 
the concept of cannabis impairment.

As far as I can find, neither USA Today nor Time covered the CU 
study. I did find the headline for the USA Today government driving 
survey: "Study finds new driving threat from dopers, druggies."

Respond: You can hear Leland discuss his most recent column and Colorado 
cannabis issues each Thursday morning on KGNU.
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MAP posted-by: Jay Bergstrom