Pubdate: Tue, 02 Apr 2002
Source: Winnipeg Free Press (CN MB)
Copyright: 2002 Winnipeg Free Press
Contact:  http://www.winnipegfreepress.com/
Details: http://www.mapinc.org/media/502
Author: Helen Branswell

HEY DUDE, WHERE'S MY IQ? TIME TO BUTT OUT

TORONTO  (CP) -- It seems Hollywood isn't wrong when it portrays stoners 
as, well, dumb. Heavy marijuana use does seem to drive down the IQ, by an 
average of four points, researchers from Carleton University report in 
today's issue of the Canadian Medical Association Journal 
(www.cma.ca/cmaj). The good news? The decline appears to right itself if 
the dope smoker butts out.

"A negative effect was not observed among subjects who had previously been 
heavy users but were no longer using the substance," researchers wrote.

"We conclude that marijuana does not have a long-term negative impact on 
global intelligence."

The issue of whether marijuana use has an impact on IQ is a contentious one.

Resolving the issue has been tough, said lead author Peter Fried of 
Carleton's psychology department, because of the difficulty of coming up 
with before and after pictures of each subject's IQ. Fried and his 
colleagues had a neat answer to the problem. Since 1978, they have been 
following a group of children whose mothers -- some marijuana users, some 
not -- enrolled in the Ottawa Prenatal Prospective Study. These children 
are now aged 17 to 20.

To study the effect of marijuana on IQ, they studied a subset of 70 young 
adults, comparing current IQ scores to those on file from the subjects' 
pre-teen days.

Nine were light current users and another nine had smoked regularly in the 
past but hadn't used the drug for at least three months. Fifteen were heavy 
current users and 37 were non-users who had never used the drug on a 
regular basis. Urine samples were analysed to ensure the subjects were 
being honest about their marijuana use.

Current heavy users showed a decline in IQ of 4.1 points, which is in the 
range of the decrease seen among children whose mothers drank three drinks 
of alcohol a day while pregnant or who used cocaine during their pregnancy.

But the decrease was not seen among former heavy users.
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