Children who smoke cannabis are more likely to behave anti-socially and to have mental health problems, according to new Irish research.
Boys who use cannabis tend to turn to vandalism and theft and get into fights, while girls who use the drug are likely to misbehave at school, a four-year study of of over 4,000 pupils aged between 11 and 15 carried out at Queen's University Belfast has found.
Young males are twice as likely to have committed delinquent acts such as vandalism or carrying a knife.
Teenage cannabis users also have an increased risk of developing emotional and psychiatric problems in later life, the study found.
By the age of 15, more than 40 per cent of the schoolchildren studied had tried cannabis - a five-fold increase on four years earlier, the British Psychological Society's annual conference in Dublin heard.
Cannabis had different effects on boys than on girls, with boys more likely to engage in anti-social activities than girls who took the drug.
Discussions on this topic are now closed.