Like DUH... I learnt this in grade 9 health class!! What a waste of research.. we already know this :bash:
http://news.ninemsn.com.au/article.aspx?id=566931Dope smokers have a 40 per cent increased risk of developing schizophrenia, and taking it regularly drives the risk up two-fold, Australian research shows.
A new study by psychiatrists has reviewed the latest evidence of links between cannabis use and mental illness, concluding the association is "stronger and clearer than ever".
A pot smoker is 40 per cent more likely to suffer a psychotic episode than a non-smoker, according to the review of major published international research.
And for people who smoke daily over long periods their risk is 200 per cent higher.
"On the world stage, Australians excel in smoking cannabis, so there are very many people who fit into this category," said lead researcher Dr Martin Cohen, a psychiatrist at the Hunter New England Mental Health Service.
"In fact we're number one in the world.
"We know now more than ever that this bodes badly for our mental health."
The review, published in the latest Australian and New Zealand Journal of Psychiatry, calculates that about 14 per cent of all cases of psychosis would never have occurred had the patient not picked up a joint.
A third of all Australians have smoked at least once in their life, with about 300,000 using daily. And while all had increased their risk to some degree, there was growing evidence that genetics predisposed some people even more.
Scientists have found a gene called COMT that, when faulty, is unable to break down the brain chemical dopamine.
An overload of dopamine triggers psychosis and, as cannabis produces an excess of the chemical, people with this "fault" are vulnerable.
Between 10 and 25 per cent of the population are believed to have the faulty gene, but as yet there is no way to test for it.
The risk is also higher for people who start smoking young and those who use heavily.
A 1998 national drug survey of 14 to 19 year olds showed 20 per cent had smoked in the last week, and 20 per cent of these took their first puff before they turned 12.
"These teenagers are the ones we really need to worry about because their use is changing a developing brain," Dr Cohen said.
Professor Jan Copeland, director of the National Cannabis Prevention and Information Centre, said the levels of cannabis use had declined significantly since the 1998 survey, especially among school-aged Australians.
"But while we're deterring many from ever trying, established regular users are still finding it very difficult to give up, putting them at risk of not just psychosis but depression as well," she said.
Do you believe marijuana is a risk to mental health?