Cannabis Raises The Risk Of Psychosis
Aug 24, 2007 by Andrew Hull
A team from Bristol University, writing in the Lancet said that cannabis users are 40% more likely than non users to suffer a psychotic illness such as schizophrenia and that young people need to be made aware of the dangers which they said increase with heavier use.
The Bristol team looked at 35 studies on the drug and mental health and concluded that most frequent users of cannabis have twice the risk of non users of developing psychotic symptoms such as hallucinations and delusions. They added however that a link to depression and anxiety was less clear.
The authors said that the risk of any individual developing schizophrenia remained low overall but because cannabis use was so common they estimated that it could be a factor in 14% of psychotic problems amongst young adults in the U.K. and that because all the studies found an association it seemed appropriate to warn members of the public about the possible risks.
They said that they could not rule out the possibility that people at a higher risk of mental illness were more likely to use the drug and the
study’s author, Professor Glyn Lewis a professor of psychiatric epidemiology said, "It is possible that the people who use cannabis might have other characteristics that themselves increase risk of psychotic illness”.
There are an estimated 2 million regular cannabis users in the U.K. and its class C rating means that its possession is in most cases a non-arrestable offence.
This month however Prime Minister Gordon Brown announced a consultation on reclassifying cannabis as class B, following reports that more potent strains such as "skunk" are becoming widely available.
Marjorie Wallace, chief executive of the mental health charity SANE, said, "This analysis should act as a serious warning of the dangers of regular or heavy cannabis use. The headlines are not scaremongering but reflect a daily, and preventable, tragedy”.
In a separate article experts said that up to 800 schizophrenia cases a year in the U.K. could be linked to cannabis use.