POT USE DAMAGES TEEN BRAINS, STUDY FINDS

Smoking pot every day can permanently alter a teenager's brain, new
research from McGill University says.

The results of the study at the Research Institute of the McGill
University Health Centre so surprised the scientists, they redid it
twice. "We didn't believe in our results, so we did it three times.
We always had the same results. All of the subjects responded in the
same manner," Dr. Gabriella Gobbi, a psychiatric researcher and
McGill professor, told the Star.

Those results showed that long-term use of marijuana by a teenager
decreased the compounds serotonin and norepinephrine in the brain,
which in turn sapped the subjects of motivation and the ability to
handle stress while increasing depression. The study suggests the
long-term effects are irreversible.

"It means cannabis is more dangerous than we thought for
adolescents," Gobbi said.

"It's not an easy message to transmit. In the last 10 to 20 years,
marijuana was perceived as a safe drug. It's not easy to change this culture."

In the short-term, Gobbi said, there was evidence that marijuana in
low doses increases serotonin, giving an "antidepressant effect." The
long-term effect, however, was the opposite.

"This doesn't mean adults are not affected," said Gobbi. "But we
didn't expect to see this strong an effect on adolescence" when
brains are still in development.

Previous studies have tracked changing attitudes in teenagers who
smoke pot, but Gobbi said this is the first to nail down the impact
on "the neurobiology mechanism," or chemistry of the brain, when
tracked against consumption.

The McGill study used rats, which have a 20-day adolescence, said
Gobbi. They were exposed to marijuana for all 20 days.

"The implications are that there should be a warning about the
consumption of cannabis during adolescence because of the long-term
effects in the brain devoted to the regulation of emotion."

The study was funded by the Canadian Psychiatric Research Foundation
and published in Neurobiology of Disease.