The Age AU, April 16, 2007
CANNABIS users who started smoking as teenagers
are more likely to suffer long-term harm, including poor mental health, than
drinkers who started using alcohol as adolescents, a major study has found.
Heavy users of marijuana are also more likely to
graduate to other drugs such as amphetamines and ecstasy than are teenage
Involving nearly 2000 Victorian high school
students aged 14 or 15, the landmark study has traced their progress since
1992, and provides the first comparison of the consequences of the two
substances commonly used in teenage social situations.
Researcher George Patton, who conducted the
study for Melbourne University's Centre for Adolescent Heath, said that while
both alcohol and cannabis carried health risks, the overwhelming evidence was
that cannabis was "the drug for life's future losers".
"It's the young people who were using cannabis
in their teens who were doing really badly in terms of their mental health,"
Professor Patton said.
"They were also less likely to be working or be
qualified or in a relationship and more likely to be using other substances
such as ecstasy, amphetamines, cocaine and even tobacco.
"Effectively, for a substantial number of
high-risk users in our sample, cannabis was the drug that was preferred as
Broadly, the study confirms alcohol and cannabis
are commonly first used in the vulnerable adolescent years.
Of the 1943 survey participants, from 45 private
and public schools around the state, 80 per cent said they had used alcohol or
cannabis by the age of 17.
Almost two-thirds had tried cannabis before they
Strikingly, those defined as heavy users from
the age of 15 or 16 had by then selected one substance — alcohol or cannabis —
over the other and tended to stick with their drug of choice into their 20s.
Professor Patton said the findings reflected the
changing use and attitudes to cannabis by teenagers.
"Twenty or 30 years ago, cannabis was uncommonly
used by teenagers," he said. "Alcohol use is still more prevalent, but
cannabis use has become widespread … in many countries."
While patterns of use intensified as they grew
older, only one in 25 survey participants were classified as taking either
alcohol or cannabis at "very high risk levels" in their teens.
This was defined as using cannabis every day or
in the case of alcohol, exceeding 43 standard drinks per week for boys or 28
for girls — more than the guidelines for very risky drinking by adults.