EARLY MARIJUANA SMOKING TIED TO LATER DRUG USE

Teenagers who smoke marijuana before the age of 17 are far more likely to
progress to harder drugs and to become dependent on drugs or alcohol later
in life, according to a new study.

The research, published in Wednesday's edition of the Journal of the
American Medical Association, found that access to pot at a relatively
young age "may reduce perceived barriers against the use of other illegal
drugs and provide access to these drugs."

While the study, by a group of Australian and U.S. researchers, lends
credence to the gateway theory (that holds that marijuana, while rather
innocuous in itself, opens a gateway to far more addictive and harmful
substances), the scientists caution that Reefer Madness-like behaviour --
an allusion to the classic antimarijuana movie -- is far from inevitable.

"I think one important thing to say to the parents of a 16-year-old using
marijuana is that the majority of kids who use cannabis do not go on to
experience problems with drugs or alcohol, but it's important that we, as
parents and as a society, recognize that there is an increased risk," said
Andrew Heath, director of the Missouri Alcoholism Research Center, and lead
author of the study.

He said marijuana use is so commonplace today among teenagers and their
parents that they have lost sight of the fact that pot smoking can lead to
problems down the road.

The study, which was conducted on 311 pairs of Australian twins who were
monitored over decades, found distinct differences between the behaviour of
those who smoked marijuana before the age of 17 and those who did not.

Among the early pot smokers, 48 per cent went on to snort cocaine, 35 per
cent to use hallucinogens and 14 per cent to inject heroin. Forty-three per
cent of the early users later became drug or alcohol dependent. These rates
were between 2.1 and 5.2 times higher than among their twins who did not
experiment with marijuana at an early age.

Michael Lynskey, a senior research fellow at the Queensland Institute of
Medical Research in Brisbane, Australia, and co-author of the study, said
that by studying twins raised in identical circumstances, researchers were
able to rule out that these differences in drug use were explained solely
by genetic or environmental factors.

He said lifestyle and personal choices -- such as whether to smoke
marijuana or not -- clearly play a role in risky behaviours and the
development of dependencies, and so does access at an early age.

"It is often implicitly assumed that the association between cannabis and
other drugs is somehow pharmacological, that using cannabis changes your
brain or makes you crave other drugs," Dr. Lynskey said. "But there are a
number of other potential mechanisms, including access to drugs,
willingness to break the law and likelihood of engaging in risk-taking
behaviours."

An estimated 1.5 million Canadians smoke marijuana recreationally on a
regular basis, according to earlier research published in the Canadian
Medical Association Journal.

Pot has been outlawed in Canada since 1923, though the federal government
is planning to decriminalize possession of small amounts for personal use.