Long-term marijuana users are dopey if they think their habit is harmless because they will suffer a range of health issues including premature ageing, a new study has found.
Long-term use of cannabis increased the biological age of those studied by 11 per cent, said co-author of the study, Stuart Reece from University of Western Australia School of Psychiatry and Clinical Neurosciences.
A 30-year-old long-term cannabis user would have a similar biological age of a 33-year-old due to the impact of the hardening of arteries, he said.
The study, which was published in the British Medical Journal Open, compared 11 cannabis-only users, 504 tobacco users, 114 combination tobacco and cannabis smokers and 534 non-smokers over a five-year period.
"We found that for those who used cannabis over a long time, not only does it age you, it increases ageing at an exponential rate over time which is alarming," Prof Reece said.
He said it was concerning that this was the first study to look at the long-term effects of smoking cannabis on the cardiovascular system.
"It is important to the health of populations worldwide that such research be continued, with the study highlighting the large-scale costs to the health system from cannabis use," he said.
Health sectors should conduct further studies on cannabis, he said, saying there would be cost implications down the track when the health system was lumbered with heavy cannabis smokers who were sicker than they should be for their age.
Prof Reece strongly opposes the recent legalisation of medicinal cannabis use in Australia saying the federal government was "putting the cart before the horse", as the health benefits on medical cannabis were still inconclusive.
"They cannot regard the benefits as proven, there's a rumour that is proven but the rumour comes from the drug companies and the drug companies' trials," he said.
"It's driven by media hype, it's not driven by the science. People are buying into an illusion and the illusion will shatter in time."
Clinical trials have shown some evidence of cannabis having health benefits for treating epileptic seizures and reducing chemotherapy related nausea.
Three US states: California, Nevada and Massachusetts voted to legalise the recreational use of marijuana during last week's election.
