Source: The Australian STUDIES of chronic cannabis users were reinforcing the belief that daily marijuana smoking could cause depression and possibly suicide in young adults, mental health group beyondblue said. Beyondblue spoke out today after Melbourne's Royal Children's Hospital released an outline of a seven-year study research program on 2,000 young adults. The director of the hospital's Centre for Adolescent Health, Professor George Patton, said the research produced strong evidence that heavy marijuana users were more prone to depression and mental problems. Details of the study will be published in an international medical journal next month. Beyondblue chief executive, Professor Ian Hickie, said depression and anxiety were the most common mental health problems encountered by young Australians, affecting 10 per cent of children and up to 20 per cent of adolescents. Prof Hickie said there was growing evidence, compiled by Australian and international research groups, that linked marijuana use and depression. Cannabis smokers who were depressed had impoverished social lives, fared badly with their education and had trouble with work, beyondblue said in a statement today. Gus Lee, 39, was now building a home renovation business, a venture he said was impossible during 21 years as a heavy marijuana smoker. "I'd get stoned and have a good idea of doing something and a few hours later I'd still be on the couch," he told ABC television. "I wore out a couch and a remote control unit from lying there daydreaming about all the things I was going to do. "I certainly had suicidal thoughts a lot of the time and acted on it a couple of times." Mr Lee said after a serious suicide attempt five years ago which landed him in a psychiatric ward he stopped smoking cannabis and began developing his home renovation business. Dr Jane Burns, manager of beyondblue's youth agenda, said research was confirming theories that regular marijuana use, like regular alcohol consumption, heightened sensitivity to depression and anxiety and placed young people at greater risk of suicide and suicidal behaviour. Prof Patton said the Royal Children's Hospital study was the best evidence yet that cannabis was a health risk which led to mental illness and depression. It has not so far been proven that cannabis use causes depression. Rather, it is thought that depressed people might have turned to it for relief or that some personality types could be prone to both cannabis dependence and depression. He said occasional or experimental use probably had no effect on mental health at all.