HTTP/1.0 200 OK Content-Type: text/html Smoking Pot No Risk To IQ, Study Says
Pubdate: Tue, 02 Apr 2002
Source: Globe and Mail (Canada)
Page: A7
Copyright: 2002, The Globe and Mail Company
Author: Andre Picard, Public Health Reporter


Smoking Pot May Leave You Stoned, But It Apparently Won't Make You Stupid.

Researchers at Carleton University have found that people who smoke 
moderate amounts of marijuana, even over a number of years, do not 
experience decreases in IQ.

And while the IQ of current heavy smokers (more than five joints a week) 
dips slightly, those losses do not seem to last over time. Former pot 
smokers, no matter their intake, show no long-term decreases in 
intelligence quotient.

"Marijuana does not have a long-term negative impact on global 
intelligence," said Peter Fried, a professor of psychology at Carleton 
University in Ottawa.

He cautioned, however, that more research is required to determine whether 
smoking pot affects specific intelligence functions such as short-term 
memory and attention span.

The study, published in today's edition of the Canadian Medical Association 
Journal, is one of the first to look at the long-term impacts of marijuana 
on young people who could be examined before and after they took up the habit.

Dr. Fried is director of the Ottawa Prenatal Prospective Study, which, 
since 1978, has followed a group of people from birth onward. Their IQs 
were tested at ages 9 to 12, and again at ages 17 to 20. For this aspect of 
the research, a group of 74 subjects were questioned about marijuana use, 
and urine tests were conducted to test for the presence of cannabinoids.

As preteens, the group had a mean IQ score of 113.8, and it rose to 116.4 
as adults. Among light users of marijuana, scores rose almost six points in 
that period, while among heavy smokers, scores fell by four points. Among 
former users, IQ rose 3.5 points, regardless of previous levels of 
marijuana use.

In the study, more than one in five of the young people smoked heavily -- 
more than five joints weekly, with an average of 14 joints a week. But 
surprisingly, the former heavy users -- 37 joints weekly on average -- did 
not seem to suffer intelligence impairment.

The psychologist said the results of his research are preliminary.
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