New research by the Government’s drug advice website, FRANK, has found 42 per cent of teenagers know someone who has had mental health problems caused by cannabis.
The figures come after an Institute of Psychiatry study showed healthy people who try cannabis only once are at risk of showing behaviour linked to schizophrenia.
64% of the 27,000 young people questioned in the FRANK study were aware that cannabis could cause panic attacks.
41% knew it could bring on paranoia and 38% said it could result in memory loss.
More than half said cannabis was linked to losing motivation and doing badly at school or college.
However, the FRANK service has itself been the subject of fierce criticism from anti-drug campaigners over its drug advice.
FRANK’s information page on cannabis says: “If the recent increase in availability of stronger forms of cannabis does lead to an increase in total use by some people, this might also lead to an increase in their future risk of developing mental health problems. Nobody knows the answer to this question yet”.
But Mary Brett of Europe Against Drugs said: “FRANK has been stuck in a time warp. Their website still isn’t up to date.”
“They have always said you should steer clear of cannabis if you have a history of mental illness. It doesn’t seem likely that the damaged people known to 42 per cent of teenagers all had a history of mental illness.”
Tests from the Institute of Psychiatry at King’s College, London, in July are the first to investigate the impact of exact doses of cannabis.
Researchers injected 22 healthy students and academics with Delta-9-tetrahydrocannabinol (THC), the main active ingredient of the drug.
The results revealed that half the subjects showed an “acute psychotic reaction”.
In April, FRANK was criticised for telling young people that cannabis is less harmful than alcohol.
A reporter posing as a 13-year-old worried about a friend using cannabis was told: “If you just keep it at weekends, I don’t think it’s likely to cause him any major problems.”
At the time Neil McKeganey, professor of drug misuse research, called the advice “misplaced, pro drug propaganda, targeted at young people and dressed up as advice and support”.
Cannabis was reclassified to the class B category of illegal drugs in January 2009.
The drug was controversially moved down to class C in 2004 by former Home Secretary, David Blunkett.
Police, parents and mental health experts called for a tightening of the law because of the risks associated with using the drug.