BOGART THAT JOINT

Before your 17-year-old waves yesterday's Globe and Mail in your face and
says, "See, man: Marijuana doesn't make you stupid," prepare yourself by
reviewing the evidence. Yesterday's report, of a study by Peter Fried, a
psychology professor at Carleton University in Ottawa, actually found
considerable harm done to intelligence levels among heavy marijuana users.
The key is that the harm exists only during the period that they are using
marijuana regularly, and not over the long term. Provided they stop.

By smoking five or more joints a week, users are lopping four points off
their IQ -- which is roughly the effect felt by children whose mothers
smoked crack cocaine when they were pregnant, or consumed three alcoholic
drinks a day.

As long as they habitually smoke weed, they have every bit as good a jump
on life as a former crack baby, or someone growing up with fetal alcohol
syndrome. Like the rest of this luckless fraternity, they're now at much
higher risk of dropping out of school or being fired from their job. And
they may discover the brutal joys of addiction -- scientists now believe
that today's highly potent marijuana (roughly five times as strong as that
sold on the street 30 years ago) can be psychologically and physically
habit-forming.

Why did any of the heavy users in Dr. Fried's study quit? They told him
that their short-term memory and attention span were suffering. Whether
that effect lasts, Dr. Fried doesn't know. As he stressed in his report, he
didn't measure these other crucial elements of cognition.

Noteworthy, too, is that Dr. Fried's sample of heavy users was small, with
only nine people. Keep in mind that lab tests on rats have found lasting
brain damage in about 5 per cent of those heavily dosed with marijuana.
Regular teenage users, whose numbers have been growing sharply in the past
few years, should know that they are dumbing themselves down, in more ways
than one.