More hyped nonsense this week about cannabis (whether it is ‘dangerous’ by causing psychosis, whether it should be reclassified to B, and so on). Although based on a Lancet study (a meta-analysis of previous work ), once the media and politicians got hold of the research it became a lot more robust than the study’s authors would hold.
The media:
Cannabis use linked to 40% rise in risk of schizophrenia The Guardian… ‘at least 800 people suffering serious psychosis in the UK after smoking the drug’
‘Cannabis doubles psychosis risk’ ITV
Dope ’causes schizophrenia’ The Sun
The scientists:
‘In conclusion, we have described a consistent association between cannabis use and psychotic
symptoms, including disabling psychotic disorders. The possibility that this association results from confounding
factors or bias cannot be ruled out, and these uncertainties are unlikely to be resolved in the near future.’
And that’s just the questions internal to cannabis use, never mind looking at the issue in the wider context.
Internally, what we don’t know are:
1. are any psychotic symptoms temporary and directly caused by cannabis, as opposed to long-term? If yes, then ceasing use may cause some people to be cured of their problem. (this is, to some extent, addressed by the analysis).
2. what causes what? or are they in symbiosis? Some studies reported try to deal with this by excluding those with psychotic symptoms, but we don’t know about underlying problems. One study assessed kids at 11 for psychotic symptoms but what we can’t know is whether, say at 14, a child starts having symptoms (perhaps caused by family stress) and then self-medicates with cannabis. Self-medication is often behind all kinds of drug use (for cannabis here’s one study). Alcohol is similarly used to alleviate depression. Perhaps there’s a downward spiral, or the drug could be useful: we don’t know. We need a controlled experiment!
3. Why hasn’t the huge rise in cannabis use resulted in a massive increase of people with psychotic illnesses? My theory would be that most people are light users, and the heavy users are probably poly-drug users who may well have been mixing alcohol and amphetamines if they were a generation earlier.
Which brings us to the issues of context. Saying that 800 cases of 18-34 year olds could be avoided if they didn’t smoke dope raises some interesting questions. Is this a lot or only a few? If they hadn’t taken cannabis, would they have taken something else instead? Would there be any other harms?
In particular, the problem of alcohol is highly relevant. It’s legal, yet can cause schizophrenia. 10% of people have anxiety disorders and often alcohol is used to overcome this (perhaps we all do… it’s the social lubricant effect) – that’s a lot of people. Alcohol is implicated in lots of crime – over half of the incidents of stranger violence. And apparently 3.8million people in England and Wales are alcohol dependent – that’s also a lot of people. But for most of us it actually makes are lives a bit better.
Of course any drug taken to excess, or in a dependent way, is going to be bad for us. And even in small doses they may do some harm. However, for most people the personal benefits (relaxing, the joie de vivre, the sociability and so on) outweigh the personal harms. Educating people to not overdo it would be a good approach. And when dealing with the wider harm to society, I think cannabis should be of low priority. The RSA’s report is a good start for some sensible discussion of what to do about the problem of drugs and alcohol in British society.
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