This from The Telegraph (UK):
Drug abuse: Children of 10 and 11 are involved
Last Updated: 1:58am GMT 15/11/2006
Heroin, crack cocaine and cannabis blight huge swaths of Britain's inner cities and sink housing estates.
Drug abuse has become a crucial driver of the family breakdown and under-achievement of a generation of young working-class white boys.
Today's report stresses both parents and their children are taking drugs in many of the poorest housing schemes.
Even so-called "soft" drugs like cannabis can have a major impact on young people. It highlights evidence from Professor Peter Jones, of Cambridge University, a leading psychiatrist, who said cannabis had become a "huge issue".
He warned that children as young as 10 and 11 were taking the drug and, in the process, trebling their risk of developing schizophrenia.
He said that four out of five first episode psychiatric disorders occurred among heavy users of cannabis or people who were dependent on the drug.
"I think this is an iceberg effect. If you were able to measure the toll on GCSE results, A Level results, training and social development, we would have a much bigger number of deleterious effects," said Prof Jones.