STUDY: POT SMOKING NOT LINKED TO IQ DECREASE

Smoking pot may leave you stoned, but it apparently won't make you stupid.

Researchers at Carleton University in Ottawa 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.

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.

"I don't want people to read this and think there are no long-term effects
from smoking pot," Fried said.

The new study, published in the current 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.

Fried is director of the Ottawa Prenatal Prospective Study, which, since
1978, has followed a group of people from birth onward. Their IQ was 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.

"A four-point drop in IQ may not seem large for an individual, but it is
significant in a group," said Fried, expressing concern about excessive use.

He said he was surprised both at how many young people smoked marijuana and
the quantities ingested. Almost half had smoked pot. That is considerably
higher than a larger survey conducted by the Center for Addiction and
Mental Health in Toronto, which found that 29.2 per cent of teens smoke
marijuana and 28.3 per cent smoke cigarettes.

In the new study, more than one in five of the young people smoked
marijuana 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.

Fried added, however, that the majority said they quit because they were
suffering from short-term memory loss and concentration problems.

The psychologist said the results of his research are preliminary, but he
published them in direct response to an editorial in the Canadian Medical
Association Journal that advocated decriminalization of marijuana, saying
research shows "minimal negative health effects with moderate use."

The journal said the penalty for marijuana possession should be similar to
a parking infraction.

Fried said that while he agrees laws need to be changed, he is worried that
the debate has been grossly oversimplified. "You can't just say,
holus-bolus, that the drug is innocuous. Despite widespread use, there are
huge gaps in our knowledge."