drug use 'aggression link'
Cannabis use by children increases the
risk of aggressive behaviour, but does not lead to them
becoming withdrawn, a Dutch study says.
Previous research on the drug has linked
it to "internalised" problems such as depression.
But the British Journal of Psychiatry
study of 5,000 children said it was more likely to cause
external problems such as delinquency and aggression.
UK experts said the "jury was still out"
about such an effect.
The findings comes as figures show more UK
children are being exposed to cannabis.
Last year, a report by the Schools Health
Education Unit, a government research team which has been
tracking young people's experience of drugs since 1987,
found over half of 14 and 15-year-olds had been offered
cannabis, with one in four having taken it.
The latest study, by a team at the Trimbos
Institute, a mental health research centre in the
Netherlands, analysed the results of questionnaires filled
in by 5,551 young people aged 12 to 16.
They found 17% had used the drug in the
Researchers found the strength of the link
increased with higher use of cannabis.
However they found children who had used
cannabis, but not in the previous year, were not at higher
risk that those who had never used cannabis.
They also found more heavy cannabis users
- children who used the drug 40 times a year or more -
reported poorer school grades than those who did not use the
And researchers added that, while no link
was found between cannabis and mental health problems such
as depression, that did not mean there was no connection
between the two for some vulnerable people
Previous studies has found that long-term
cannabis use can increase the risk of depression.
Report author Harald Wychgel said the
findings could be even more acute in countries which did not
have such a liberal approach to cannabis - the drug is not
illegal in the Netherlands.
He said: "At young ages the use of
cannabis is already strongly associated with delinquent and
aggressive behaviour even after controlling for strong
confounders such as alcohol and smoking."
Paul Corry, of mental health charity
Rethink, said researchers were beginning to look at the
links between aggression and mental health.
"There have been some studies which have
found similar things, but I would say the jury is still out.
What is not clear is where it is cause or effect. "Are these
children already aggressive and the environment they are in
increases the risk of them using cannabis?
"We have much more evidence that cannabis
use is linked to feelings of anxiety and hallucinations."
Source BBC News