Young people need to be warned about the link between cannabis use and psychosis, a conference on drug use was told this morning.
Dr Des Corrigan, chairman of the National Advisory Committee on Drugs, also warned delegates at Chilling Out or Numbing Out, of the dangers of a "free gaff".
Organised by the Dublin North East Drugs Task Force, the conference focused on the ambivalence surrounding cannabis use in young people.
Dr Corrigan said frequent users of cannabis double their chances of developing psychosis, including schizophrenia. But for people who used cannabis and are genetically susceptible to schizophrenia the risks increased 10 fold.
The kinds of cannabis used also affected outcomes. While grass and marijuana contained lower levels of euphoriant compounds alongside anti-psychotic compounds, hash contained more euphoriants and hash oil contained the most. Studies showed that users of cannabis with higher euphoriant levels had more mental health symptoms.
Mr Corrigan also warned parents that most young people obtain cannabis from a friend. "There was no mysterious pusher or dealer," he said.
"Young people's friends are crucial. Do you know who your children's friends are and do you know who their parents are?" he asked. He also warned of the dangers of a free house. "The "free gaff" is a disaster," he said.
Gerry McMahon, chairman of the task force, said people needed to put to bed the myth that cannabis use is of little or no harm. Denial and ambivalence featured strongly and persistently among all age groups, but particularly among adolescents.