POT smokers suffering from the early stages of schizophrenia are stuck in a vicious cycle of drug abuse and psychotic attacks, an Australian study has found.
Research by the University of Melbourne found that the more marijuana a psychotic person used, the worse their condition got.
And once they suffered a relapse in delusions and hallucinations they were more likely to turn to marijuana to cope.
The work, published in the latest British Journal of Psychiatry, tracked 81 Queenslanders who had developed a psychotic mental illness in the past six months.
The subjects were typically male, aged in their early 20s, single, unemployed and addicted to marijuana.
Researcher Dr Leanne Hides monitored their drug use and mental condition weekly over six months, discovering that almost all were caught up in a vicious cycle that was impossible to escape.
"We found that cannabis use contributes to a relapse in psychotic episodes and then as a result of that they are more likely to use cannabis," Dr Hides said.
"Basically, they're going around in circles and they can't really win."
Statistically, the study found that for each day a psychotic person used cannabis during a week, the chance of a relapse increased by seven per cent.
And for each new low in their condition, the chance of self medicating with marijuana also rose.
"So the message is: if you smoke cannabis and have psychosis you're going to stay very unwell," she said.
Dr Hides said the problem stemmed from the fact that many relied on cannabis to lift them out of depression and anxiety caused by their condition.
"The trade off for them is they're more likely to have a serious relapse in their illness," she said.
"As far as they're concerned it's worth it, but it comes at a serious cost."
The researchers have called for early intervention for substance abuse in young people to break the cycle before it becomes ingrained.