Children who smoke cannabis are twice as likely to offend
Children who smoke cannabis are twice as likely to get into trouble – both in the classroom and outside the school gates.
Boys turn to vandalism, theft and fights, while girls misbehave at school, a four-year study of thousands of pupils aged between 11 and 15 found.
Young males are also up to twice as likely to have committed “delinquent” acts such as vandalism or carrying a knife.
And teenage cannabis users have double the chance of developing emotional and psychiatric problems in later life.
The finding was released as Gordon Brown comes under pressure to reverse Labour’s downgrading of cannabis.
Calling on the Government to do more to combat drug use in teenagers, researcher Laura Grant said: “Cannabis has been regarded as potentially being a gateway drug to harder drug use, leading to mental health issues, leading to memory loss or impairment and having an impact on learning and social behaviour.
“I have spoken to kids that smoke cannabis every single night, they get up and go to grammar school and get good grades.
“This really is a hidden issue that needs to be tackled.”
She added: “These young people are still attending school and are at odds with the general perception of what the typical young person is like who engages in these acts.
“It is no great leap to imagine that this school-attending high risk group may be a further risk of later life problems as a result of their early drug use: mentally, socially and emotionally.”
Miss Grant, a sociologist at Queen’s University Belfast, studied data tracking the health and habits of almost 4,000 Northern Irish schoolchildren.
By the age of 15, more than 40 per cent had tried cannabis – a five-fold increase on four years earlier, the British Psychological Society’s annual conference in Dublin heard. She added it was unclear why cannabis had different effects on boys and girls.
A fifth of those studied were judged to be at risk of developing mental health problems in later life, with cannabis users running up to double the risk of other children.
Cannabis use in British teenagers has increased tenfold in the last 20 years. By the age of 16, almost four in ten will have tired cannabis and almost one in ten is a regular user.
In 2005, 10,000 youngsters aged between 11 and 17 were treated for cannabis use.
Previous studies have shown a clear link between cannabis use in the teenage years and mental illness in later life.
It is thought that used during the developmental years, the drug may do permanent damage to the developing brain.