Despite repeated attempts by journalists/interviewers to make a claim otherwise for what the study said, it is NOT the case that if you smoke cannabis once or twice you are 40% more likely to experience mental health problems.
What the study actually said - as far as said journalists/interviewers would allow the authors and commentators to say - was that looking at the group as a whole of those who smoked cannabis (from those imbibing every week, day, hour to those who had had some occasional, irregular or one-off usage), users were 40% more likely to develop some mental health problems. So the impact is averaged out. I would say that suggested that high users were much more likely: a fact that has been well-known for many years, if not decades, and that frankly you'd have to be pretty dense not to have anticipated. Although, there is the issue of whether the propensity of mental ill health comes before the drug use, stimulates the likelihood of drug use, and how it exacerbates the effects of drug use: heck, even the BBC site had to allow them this one -
[the authors] could not rule out the possibility that people at a higher risk of mental illness were more likely to use the drugSo my point is this. We're generally getting muddled on cause and effect here. Also, screaming about classification is misdirection. I don't think it was especially smart to change the classification, but it was changed and despite a lot of shouting by all accounts "the incidence of schizophrenia has not shown any significant change in the past 30 years" despite (any) changes in cannabis usage. I can't find the figures but I'm also pretty sure that cannabis use isn't particularly rising, but what is/may be changing is the type of cannabis generally available.
So, how helpful is the current media attention on this particular study into the existing research on the impact of cannabis use and its association with mental health difficulties? [Note how I'm on about the media coverage more especially than the Lancet's meta-study of existing research].
I would actually say the hoo-ha 'not very helpful at all'. Why? Because it isn't really telling us anything most people didn't already know. Doing something excessively doesn't do you any good. Moreover, the definition of 'excessively' may be difficult to define and could vary across individuals. So it's probably not a great idea to do it at all but mostly the paranoia surrounding an individual's usage is - for most people - going to be much worse than any impact the drug may have. Oh My God! You smoked one spliff! You're obviously now going to be 40% more likely to develop schizophrenia!
The study's public profile has more particularly been linked with the perception/reality that Gordon Brown would like to roll back the Blair government's previous decision to reclassify cannabis. Well, as I have already indicated, I actually think closer review of current figures may reveal classification to be something of a decoy duck problem. Would it be practical to establish particular forms of cannabis as a higher category? Not sure? But if you can't split it - and my sense is it would be a 'mare to do so for all regulatory and policing bodies concerned - then how would raising back up the classification help? Would that discourage (young) users? I don't think so.
Mental health difficulties cause incredible pain and distress to those experiencing them, and to the people around them. I have no wish to dismiss just how painful that can be. But it seems to be a gross misuse of statistics to lay so much blame at the door of one drug and to scaremonger the public's perception of its impact. Having seen first hand the negative impact of any excess on the people around me - cannabis, alcohol, tobacco - I would never allow anyone to think that I am blase about the effects of such habits. But what I do rail against is indiscriminate use of statistics to make crappy soundbite points about such a serious issue as the overall mental wellbeing of human beings.