Cannabis and other illegal drugs could help speed up the onset of psychotic illnesses in young people.
This is according to research published in the latest edition of the Australian and New Zealand Journal of Psychiatry, which found that those at risk of schizophrenia could suffer from the condition a year earlier for every illicit drug they take.
The Sydney Morning Herald reports that heavy users of cannabis, cocaine and amphetamines experienced their first psychotic symptoms at a younger age than those who abstained or took one of these.
This is the first evidence that taking additional drugs could further accelerate the development of such illnesses.
The mean age of onset of schizophrenia for non-drug using males was 23.3, compared to 22.5 for those who had smoked cannabis and 19.6 years old if they had used cannabis, amphetamines and cocaine.
With such startling findings, many people are calling for greater health campaigns to warn those who are using or addicted to drugs to be more aware of the risks to their physical and mental health.
Professor Jon Currie, head of addiction medicine at Melbourne's St Vincent's Hospital, told the newspaper that early use of drugs was a risk for all young people, as the brain is still developing until the early 20s.
"The drugs can derail that normal development, which also means derailing the normal protective mechanisms, which stop you getting these mental health problems," he explained.
They can affect the brain's neurochemical systems, Professor Currie said, before adding that "they may actually alter the plasticity of the brain and the wiring and connections and have physical effects, which can be long-standing".
He was firm in his beliefs that reality-based education campaigns should be run, warning of the risks of drug use and addiction.
"The message we give is simple, it's your brain, you need it, later in life you'll really need it, don't damage it now," he urged.