Teenagers who regularly drink alcohol and smoke are just as likely as those who routinely use cannabis to engage in aggressive and delinquent behaviour, research indicates.

The findings, by a team at the Netherlands Institute of Mental Health and Addiction in Utrecht and published today in the British Journal of Psychiatry, suggest that more caution may be needed in interpreting studies linking cannabis use to mental health disorders and antisocial behaviour in the young.

Karin Monshouwer, the lead author of the research, said: “It seems to me that there may be a certain type of child or person who takes these substances in the first place. People seem to think that cannabis is worse than these other substances, but our study suggests that maybe there is no difference.”

It was perfectly possible, Dr Monshouwer added, that cannabis use might simply reflect “a drive among adolescents towards rebellious behaviour”.

The study found no association between cannabis and withdrawn behaviour, such as psychosis, but did not rule out the possibility that there is a group of vulnerable young people using the drug who are at increased risk of depression.

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