Pubdate: Fri, 18 Dec 2015
Source: Globe and Mail (Canada)
Copyright: 2015 The Globe and Mail Company
Contact:  http://www.theglobeandmail.com/
Details: http://www.mapinc.org/media/168
Author: Erin Anderssen
Page: L7

TEENS AND TOKING: IT'S NOT DOING THEM ANY FAVOURS

Legalizing marijuana is now an official goal of the federal 
government, and not just a campaign promise. Ontario's Premier even 
suggested this week that the province's liquor stores could sell weed 
next to wine. The natural worry for parents and policy-makers is what 
this might mean for teenagers. Erin Anderssen outlines what you need to know

What does science say about a teenager's brain on pot?

Researchers have definitely found some worrisome links. A University 
of Ottawa study found an increase in brain activity when performing 
cognitive tasks in teenagers who smoked pot at least once a week for 
three years - in other words, their brains had to work harder on 
tests measuring areas such as working memory and sustained attention. 
A 2014 study published in the Journal of Neuroscience also found 
structural changes in brain regions affecting emotion and reward 
processing in teens who smoked up at least once a week. A New Zealand 
study published in 2012 that followed subjects from birth into their 
40s, linked long-term marijuana use to lower IQs - particularly for 
teens who continued using into adulthood. Experiments with rats have 
also found memory deficits in rodents given marijuana extract in 
adolescence. Other research has suggested a link, especially in 
teenaged boys, between marijuana use and schizophrenia. And compared 
with their non-stoner peers, teenagers who smoked pot daily, 
according to a 2014 study published in the Lancet medical journal, 
were 60 per cent less likely to finish high school or get a 
university degree than those who didn't smoke. They were also eight 
times more likely to use other illicit drugs as adults, and seven 
times more likely to attempt suicide.

That sounds pretty conclusive. Is it?

It's safe to conclude that marijuana isn't doing the teenage brain 
any favours - and, in some cases, it's at least a factor in serious 
harm. Still, a shortcoming of many of these studies is that they 
reveal a "correlation" between pot and certain deficits, but not 
whether pot directly "caused" the brain changes, or whether those 
differences existed before the pot use. Further confounding the 
studies is the fact that teenaged pot smokers - especially chronic 
users - often differ in many ways from their weed-averse teens; for 
one, they typically drink more alcohol and use other illicit drugs. 
Scientists also speculate that the negative effects of marijuana may 
be influenced by genetics, potentially explaining, for instance, the 
connection to schizophrenia. For years, one theory has been that 
teens starting to experience the symptoms of schizophrenia were 
self-medicating with marijuana. That's been largely debunked by new 
scientific research. But it is still unclear whether mar! ijuana 
changes the brain in ways that lead to schizophrenia, or whether it 
triggers schizophrenia in teenagers already genetically disposed to 
the mental illness.

Will legalization lead to a nation of teenaged stoners?

In the summer, an American study analyzed the self-reported pot use 
among one million teenagers in 48 states between 1991 and 2014. In 
the 21 states that had passed a medical-marijuana law, researchers 
found that, while the teens in those states tended to be higher users 
in general, there was no increase in use after the law was passed. If 
legalization did translate into higher teen use, you might expect 
states such as Colorado and a country such as the Netherlands to have 
the world's most stoned adolescents. But, based on 2013 data, the 
percentage of Colorado teens who reported using pot in the previous 
month fell slightly since the law changed. And according to the 
United Nations, 17 per cent of Dutch teenagers said they had smoked 
pot in the past year - compared with 28 per cent in Canada.

So what's the Canadian story?

Teenagers here already have the highest rate of cannabis use in the 
developed world. According to the Canadian Centre on Substance Abuse, 
about 10 per cent of Grade 12 students smoked up daily. It's pretty 
clear that motivated teenagers have figured out a way to score an 
illegal joint long before politicians were talking about selling pot 
in liquor stores. What's more, the street pot they're smoking is a 
lot stronger than the kind that made the rounds at Woodstock. In the 
1960s, marijuana contained 1 per cent tetrahydrocannabinol, the 
psychoactive ingredient. Today's weed has a THC concentration of at 
least 10 per cent and, according to Health Canada, as much as 30 per 
cent. Regulating marijuana would arguably make a safer product.

So what should I tell my teenager?

Quote the science. Adolescence is a critical stage of development for 
the brain, which continues to build new connections even into 
adulthood. Parents can tell their kids that, given the preponderance 
of evidence suggesting negative and possibly permanent effects, and 
the fact that science cannot yet predict who may be most vulnerable 
to harm, smoking pot during a brain-boosting time of life is not a 
good idea. (Incidentally, parents should share the same message about 
binge drinking.) In the New Zealand study, for instance, while 
subjects who started smoking only as adults didn't show IQ deficits, 
teenagers who eventually gave up pot did not restore their IQs to the 
level of their nonsmoking peers. Many researchers suggest that 
educating teenagers about the scientific findings may be the biggest 
deterrent to drug use - whatever the law of the land.
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