Pubdate: Fri, 21 Feb 2014
Source: Globe and Mail (Canada)
Copyright: 2014 The Globe and Mail Company
Contact:  http://www.theglobeandmail.com/
Details: http://www.mapinc.org/media/168
Author: Erin Anderssen

NOT UNTIL YOU'RE OLDER

As the legalization debate quickens, scientists warn there is a lot 
we don't know about marijuana and brain development. Erin Anderssen 
examines why teens should wait to smoke up

Parents seeking direction on what to tell their teens about pot might 
take some pointers from the President of the United States, who 
explained in a recent New Yorker profile how he'll put it to his two 
daughters: "It's a bad idea, it's a waste of time, not very healthy."

Barack Obama went on to express thoughtful support for legalization, 
and described his own youthful dope smoking as "a bad habit, a vice," 
one not that different than the cigarettes he has more recently given 
up, and not more dangerous than alcohol. Many mothers and fathers of 
his boyhood would have passed out at such presidential admissions: a 
powerful, anti-pot parent movement in the 1970s had brought an abrupt 
halt to any substantive debate over decriminalization, both in the 
United States and Canada, with exaggerated worries of weed-happy, 
zombie-like offspring unable to compete in the economy.

But even with the debate over marijuana shifting rapidly - with 
decriminalization or straight legalization heavily favoured in public 
surveys, new laws in several states and endorsed by Liberal Leader 
Justin Trudeau - some scientists working in the relatively new 
research area of pot and the teenage brain say young people need more 
specifics than "not very healthy."

Researchers also worry that with the focus on eliminating overzealous 
prosecutions, easing access to medicinal marijuana and regulating 
supply to reduce the black market, a public-service message about the 
health consequences for adolescents, who make up the bulk of users, 
has been overlooked. In Canada, for instance, although rates have 
fallen in the last decade and only 10 per cent report being regular 
users, teens have the highest level of dope-smoking in the developed 
world, according to 2013 Unicef report; using data from the World 
Health Organization, the study suggested that 28 per cent of children 
between age 11 and 15 had tried marijuana within the past year. 
Having gotten the nicotine message, many have tossed the cigarettes 
in favour of weed, which, surveys suggest, they are increasingly 
likely to view as safe, even beneficial.

When it comes to marijuana, adults and teenagers have different 
risks, a burgeoning field of research suggests. A 30-year-old can 
smoke up relatively safely, researchers say, but there's a crucial 
neurological window in adolescence - and for some young users, 
getting high can have potentially, life-changing long-term consequences.

Selling a "wait till you're older" message will make most teens roll 
their eyes. Considering the deaths that result from binge drinking, 
and the highly addictive, cancer-causing effect of nicotine, pot is 
comparatively benign. Obama, after all, was simply reflecting the 
views of many parents, who toked up, moved on, and are just fine. For 
most teenagers - especially occasional users who try it later in high 
school - the pattern will likely be similar.

But scientists point out that the pot today is more potent than what 
was smoked in the seventies. For a small group of adolescents, those 
who start sooner and use more heavily, research suggests that 
marijuana may alter brain development at a pivotal time, causing 
long-term damage to working memory and even potentially trigger a 
gene that causes schizophrenia.

"It is a disservice not to give [teenagers] the knowledge that it is 
not the panacea of all positives," says Yasmin Hurd, a neuroscientist 
at New York's Mount Sinai School of Medicine who studies marijuana. 
"Some of them will be very much affected and it will change the 
trajectory of their lives.... And how do you know if you're going to 
be that person who is more vulnerable?"

For a drug that's been around for centuries, there's a lot scientists 
don't know about marijuana. Most studies, both animal and human, look 
at heavy users, and many of the effects are subtle, so it's still 
unclear how much those findings translate to more occasional use. It 
is known, however, that adolescence is an important period of brain 
development, when cross brain connections are cemented with the 
temporal lobe, a central hub for working memory and reasoning. A 
recent review of 120 Canadian and U.S. studies on the effect of 
cannabis found that early marijuana use altered brain development. A 
McGill University study found a link between daily consumption in 
teens and depression and anxiety. The connection to mental health 
issues such as schizophrenia isn't conclusive - teenagers with early 
symptoms may use marijuana to self-medicate - but many scientists 
theorize that pot smoking, early and in high doses, interacts with a 
genetic predisposition for the illness.

The role marijuana plays as a gateway drug is also the subject of 
debate. A U.S. study published last year suggested that it was 
alcohol that really started the path to such hard drugs as cocaine 
and heroin, with pot a pit stop along the way. Many teenagers never 
leave that pit stop. But in studies of juvenile rats, argues Hurd, 
the neurological link with addiction is beyond dispute.

Still, as Hurd points out, animal studies reveal the neurological 
effects in a lab. Human beings are more complex - environmental and 
social factors, as well as genes, go a long way to protecting a 
teenager from the risks of marijuana. But, says Hurd, "is there a 
potential for early marijuana exposure to change the brain in a way 
that will last into their adulthood [and] make them more susceptible 
to other drugs? Hands down, absolutely, the results shows that."

Decriminalization, however, would also make the drug scene safer for 
teenagers. A 2012 U.S. study based on national survey data found that 
the legalization of medical marijuana did not increase use among 
teenagers; European countries with more lax marijuana laws report 
lower rates of teenage use than Canada. Benjamin Hansen, co-author of 
the 2012 paper, suggests that while a lower price might make pot more 
affordable to teens, and there would be some third party sales to 
minors, regulated suppliers would restrict their sales to minors and 
reduce demand on the street. "Right now, the best person [for a 
dealer] to sell to is a 15-year-old kid," Hansen says. "How likely is 
that kid to be an undercover cop?"

Decriminalizing marijuana would also, experts say, make it more 
likely for teenagers to seek help if they run into trouble with the 
drug, and it would foster more research into addiction treatment, for 
which there are currently few options. According to Dr. Didier 
Jutras-Aswad, a researcher at the University of Montreal, who worked 
on the cross-generational rat study, only about 10 per cent of 
marijuana users will become addicted - compared to roughly 32 per 
cent of those who use nicotine or cocaine. But since pot is by far 
the most widely used illegal drug, the actual number of people 
struggling with addiction may be higher.

As the legalization debate moves forward, Jutras-Aswad suggests that 
society can learn from its history with alcohol, in which it took 
decades to develop standards for healthy use, controls on impaired 
driving and clear public-health messaging. "We can learn what to 
avoid with cannabis, and not wait for problems to happen and then 
react." For teenagers, that means clearing away the politics and the 
rhetoric, and giving them a balanced take on the best science available.
- ---
MAP posted-by: Jay Bergstrom