A big stick is not the only way to fight cannabis use

What is the real dope on cannabis? Over the past year, the prime minister and other federal ministers have been calling for a tougher criminal approach to cannabis.

The PM talks of "tolerant and absurdly compromised" attitudes towards marijuana use, saying marijuana had “caused a rise in mental illness” and was “a classic case of chickens coming home to roost”.

The South Australian cannabis laws, using civil rather than criminal penalties, were an issue in the recent state election, with the opposition reported as saying it will re-criminalise the growing or possessing of cannabis for personal use.

On the other hand, the Australia Institute's recently released report, Drug Law Reform: Beyond Prohibition, calls for a shift from law enforcement to treatment and prevention strategies, claiming far too much of the funds for illicit drugs such as cannabis are spent ineffectively on law enforcement at the expense of treatment and prevention.

Are we right to be concerned about the harms of cannabis in our community? Absolutely. And one thing we can be sure of is the polarised views about cannabis in our community.

Myths seem to abound at both ends of the spectrum. They range from the notion that any use will result in certain mental illness, to others who say there is no harm whatsoever associated with any level of use.

Well, who is correct?

The truth, not surprisingly, lies between the two. About 10 per cent of those who try cannabis will become dependent on it at some point in their lives, while nine in ten don't.

The earlier you start, the more frequently you smoke it, and the more of the active ingredient (THC) you take in, then the greater the harms.

Daily users, for example, have a one-in-two chance of becoming dependent and showing a diverse range of physical and psychological symptoms, such as anxiety, depression, irritability, poor appetite and disrupted sleeping.

One in five teenagers have smoked cannabis in the past 12 months, with boys out-smoking girls. The good news is that recent cannabis use among 14 to 19-year-old Australians has almost halved from 1998 to 2004, and has dropped from 44 per cent among 20 to 29-year-olds in 1998 to 32 per cent in 2004.

Regular cannabis use appears to increase the likelihood of psychotic symptoms occurring if the user also has a personal or family history of mental illness. Susceptible individuals who avoid cannabis have a 25 per cent chance of developing psychosis, whereas susceptible individuals who smoke cannabis have a 50 per cent risk.