Tonight, I saw a BBC programme, broadcast through Danish National Television on cannabis consumption. The programme must be applauded for it’s open-mindedness and fairness to the facts – with regards to both the benefits and hazards of cannabis use. However, one thing about it annoyed me: the host ended the programme with a remark about the hazards of cannabis use, and was keen to emphasise that cannabis (or rather, THC, the main psycho-active component of cannabis) has no place in a developing brain.
Of course I agree. No euphoriant is appropriate for developing brains or minds. But what does that really tell us about cannabis, per se? Not very much, I think.
One interesting thing about the debate on cannabis is that people tend to emphasise additional consumption, both in terms of consumer groups and consumptive behaviour and to de-emphasise substitution. If we are to have a real idea of the health effects of legalizing cannabis, we need to consider that people might drink a smaller amount of alcohol, because they’re supplementing with a joint. Or – similarly – kids shouldn’t smoke marijuana, just as they shouldn’t drink. But is cannabis a good or bad substitute for alcohol, when considering the impact on a developing brain?
There is some empirical evidence that people substitute cannabis for alcohol under liberalization, based on American data (Anderson, Hansen & Rees, hattip: Marginal Revolution). There is at least one positive health effect directly from this substitution, directly adressed in the paper through reduction of DUIs.
The total health effects of alcohol is the well known J-shape: moderate consumption (1-2 glasses of wine a day) is associated with lower risk than abstention, while consumption in excess of this amount leads to higher risk than either abstention or moderate consumption. Additionally, several clusters of adverse results from alcohol consumption is primarily associated with excessive intake – this goes primarily for accidents, etc.
What is interesting about the Hansen, Andersen & Rees paper is that they show that people substitute most heavily in these circumstances, i.e. by reducing binge drinking. In other words, they smoke cannabis when they would otherwise have gotten pissed, not (to the same extent) when they would have had a glass of Cabernet with the missus. This should inform our decision about legalisation in important ways.