Pubdate: Wed, 22 Jan 2003
Source: Independent  (UK)
Copyright: 2003 Independent Newspapers (UK) Ltd.
Contact:  http://www.independent.co.uk/
Details: http://www.mapinc.org/media/209
Author: Jeremy Laurance, Health Editor

CANNABIS USE BY CHILDREN 'RAISES RISK OF USING HARD DRUGS LATER'

Chlidren who smoke cannabis are up to five times more likely to
progress to harder drugs than those who delay experimenting with
marijuana until they are older, a study has found.

Those who started before the age of 17 were between 2.1 and 5.2 times
more likely to develop problems with drinking or drug addiction,
according to a study of twins.

The findings, published in the Journal of the American Medical
Association, lend weight to the "gateway" hypothesis that
suggests marijuana use leads young people on to harder drugs. But an
editorial said this did not mean that all young people who tried
marijuana would become heroin or cocaine addicts.

Researchers studied 311 pairs of twins of the same sex, where only one
twin had used cannabis before 17. Twins share the same background and
family experiences and identical twins share the same genetic risk.

The study was conducted in Australia between 1996 and 2000, when the
twins were aged 30 on average. The researchers took into account known
risk factors such as early drinking or smoking (of tobacco), divorce,
sex abuse or depression, and found they had little effect on the
results. There was also no difference between fraternal and identical
twins.

The authors said the findings show drug use cannot be solely
determined by genetic and/or shared environmental factors. Peer
pressure and the social context in which cannabis use occurs may also
be factors. "In particular, early access to the use of cannabis may
reduce perceived barriers against the use of other illegal drugs and
provide access to these drugs," they said.

In a commentary on the findings, Denise Kandel of Columbia University
said curbing marijuana use should prevent abuse of other drugs.
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