IQ BOUNCES BACK AFTER SMOKE CLEARS

No Lasting Effects -- Even for Those Teenagers Who Smoked an Average 37
Joints a Week for Three Years, Say Researchers

The notion that heavy marijuana smokers permanently fry their brains may be
a myth, suggests a study by a team of psychologists at Carleton University.

By comparing IQ results of 70 young people, a third of whom were heavy
cannabis users, the researchers found there were no lasting effects on
intelligence -- even among people who smoked an average of 37 joints a week
for three years in their teens.

The findings will be published today in the Canadian Medical Association
Journal, the publication of the group that represents Canada's 50,000 doctors.

The study found that IQ scores dropped while the subjects were on their
smoking sprees; but after they stopped, the numbers quickly bounced back to
the intelligence levels of their pre-marijuana days.

The teens had smoked an average of 5,793 joints each over 3.2 years before
they were tested for their smarts.

"This lack of a negative impact among former heavy users is striking," said
Peter Fried, the Carleton psychologist who led the study.

The teens were first tested between the ages of nine and 12. They were
tested again during the time they were smoking marijuana. A third IQ test
was done three months after they had quit smoking dope.

"One can say if they have recovered at three months, that recovery is for
real, as long as they don't start smoking again."

Worldwide, study results are split on the long-term effects of marijuana,
which an estimated 1.5 million Canadians smoke for recreational purposes.

The novel element of the Carleton study is that it compared subjects with
their own earlier IQ scores, unlike other studies that have compared dope
smokers with non-smokers.

"The controversy about whether there have been long-term effects or not is
roughly split down the middle," said Mr. Fried.

"To my mind, one of the major problems is not knowing how these folks were
before they ever heard the word marijuana."

The Carleton researchers also waited several months to measure subjects
after they quit smoking, while other studies have dealt with tests done
only after a day or two of abstinence, Mr. Fried said.

The Carleton subjects were mainly from middle-class families in the Ottawa
area. IQ tests showed that during their heavy smoking years, they dropped
an average of four points below their scores of a decade earlier. The more
they smoked, the more their results tumbled.

But Mr. Fried cautioned that his study does not deal with memory or
attention, so it is not known whether his subjects will experience any
long-term problems in those areas.

A controversial Australian study published last month suggested that heavy
and chronic marijuana users suffer memory loss and attention problems that
can affect their work, learning and life.

While Mr. Fried said he supports decriminalization of marijuana, he does
not believe his study will necessarily help the growing movement.

"There's no question the laws have to be changed as far as
decriminalization goes. I don't think there's any question about that," Mr.
Fried said.

"But it's not an easy thing. Should pregnant women be forbidden or warned?
If you had to fly, would you want your pilot to smoke up just beforehand?
If not just beforehand, how long? Unlike alcohol, which has a rapid rate of
getting out of the body, marijuana does not."

Mr. Fried said he was inspired to conduct his study after the Canadian
Medical Association Journal, in an editorial last May, said there are
minimal negative health effects of moderate marijuana use. (Mr. Fried found
his subjects in 1978, when he began a study testing drug use on expectant
mothers. He has been tracking their offspring since then.)

"The argument that marijuana is either innocuous, or for that matter
dangerous, is very often based on feelings or general moral attitude. The
implication is we've got all the scientific information we need when we
really do not."