ADRIANA BARTON
The
Globe and Mail | Published Thursday,
Oct. 16 2014
As Canadian youth take
advantage of easy access to the street drug, despite law-enforcement efforts,
pot’s reputation as “nature’s medicine” continues to grow, fuelling the debate
over whether to legalize marijuana use.
Politicians are taking
sides on the marijuana issue, with the Liberals championing legalization and
regulation, the NDP favouring decriminalization and the Conservatives holding
the line on enforcement. But do Canadians actually know how the drug affects
users? For teens, whose brains are in a crucial stage of development, is there
such thing as a harmless pot habit?
LEARNING PROBLEMS, OVERTAXED
BRAINS
While cannabis is not the
most dangerous of drugs, as with alcohol “it has a lot of harmful effects,”
said Dr. Harold Kalant, a professor of pharmacology at the University of
Toronto who has conducted research on alcohol and cannabis since 1959.
Marijuana hijacks normal
brain functioning in teens, and many scientists believe the drug may have permanent
effects on brain development.
Dr. Andra Smith, an
associate professor of psychology at the University of Ottawa, used functional
magnetic resonance imaging (fMRI) to compare brain activity in youth ages 19 to
21 who did not smoke pot regularly, and those who had smoked at least one joint
a week for three years or more.
In a series of published
studies, Smith assessed the youth’s decision-making, planning and meeting
long-term goals.
Smith found that the
earlier in life a young person smoked pot, the more harmful the effects on the
brain.
Earlier studies on rats,
conducted by Kalant in the 1980s, suggest cognitive deficits linked to cannabis
use may be long-term. Even after the equivalent of nine human years without
marijuana exposure, young rats given marijuana showed difficulties in learning
and memory that persisted into adulthood. But older rats given marijuana did
not develop long-lasting impairments, Kalant said, adding that the cannabis
receptors in the brains of humans and rodents work “in very similar ways.”
A more recent study,
published in April in the Journal of Neuroscience, found structural changes in
the brains of 18- to 25-year-olds who smoked pot at least once per week,
compared to those of youth with little history of marijuana use.
Using magnetic resonance
imaging (MRI), researchers from Northwestern University detected alterations in
brain regions involved in emotion and reward processing. The heavier the
marijuana use, the greater the changes in both parts of the brain, they found.
“This study really shows
that casual marijuana can be harmful to the brains of young people.” the
researchers wrote.
A BLOW TO INTELLIGENCE
Adolescents with a heavy
marijuana use risk permanent losses in IQ.
The ongoing study has followed
1,037 people born during 1972-73, from birth to their early 40s.
In a 2012 report,
researchers from Duke University analyzed data and found that the earlier and
more frequently a person smoked pot, the greater the loss of intelligence by
age 38. Compared to their IQs measured at age 13, people who had started using
cannabis as teens and maintained a daily pot habit into adulthood had, on
average, lower IQ. The decline was not small: By age 38, their average IQ was
below that of 70 per cent of their peers.
Individuals who began using
cannabis heavily as adults did not show similar losses in IQ, but quitting pot
did not seem to restore intellectual functioning in those who had been chronic
pot users as teenagers, the researchers found.
A HAZY FUTURE?
Teens who smoke pot everyday
are 60 per cent less likely to finish high school or get a university degree
than their marijuana-free peers, according to a high-profile study published in
September in the Lancet.
The researchers, mainly
from Australia, looked at outcomes from three long-term studies conducted in
Australia and New Zealand. They compared participants’ life status at age 30 to
their patterns of marijuana use before age 17.
Compared to people who had
rarely used cannabis, those who were daily users before age 17 had an 18-times
greater chance of becoming cannabis dependent. They were eight times more
likely to use other illicit drugs in adulthood, and seven times more likely to
attempt suicide.
“Delay the use of cannabis in young people is
likely to have broad health and social benefits,” they concluded.
Dr. Andra Smith summed it
up: “I don’t really care if you smoke at age 35,” she said, “but don’t do it
when you’re 13 because you’re just setting yourself up for difficulties.”
QUESTIONS
1. Is this article about
any use of marijuana at all, or heavy, regular use?
2. What do you think regular
use of marijuana means?
3. Is this article about marijuana
use in young people, older people, or people of any age?
4. Is marijuana legal or
illegal in Canada right now?
5. Why might some people
want to make marijuana legal?
6. Why might some people
want marijuana to be illegal?
7. What does Dr. Andra
Smith say about smoking marijuana earlier in life?
8. What happened with Dr.
Kalant's rats?
9. a) In the study in the
Journal of Neuroscience, how often did a person have to smoke marijuana for
there to be "changes" in the brain?
b) How old were the people in the study?
10. What does this sentence
mean: Adolescents with a heavy marijuana
use risk permanent losses in IQ.
11. What does the article
say is the connection between smoking marijuana everyday and finishing
high school?
12. a) What does the
article say is the connection between marijuana use as a young person and
suicide attempts?
b) Why might this be a difficult
connection to prove?
13. Why does the researcher
say "I don’t really care if you smoke marijuana at age 35"?
14. Why does the researcher
say "don’t do it when you’re 13 because you’re just setting yourself up
for difficulties"
