It has always seemed remarkable to me that the ingestion of a single substance can have such complex effects on behaviour. Alcohol does it, in part, by promoting the effects of inhibitory neurotransmitters and suppressing the effects of excitatory ones, while also whacking up a nice surge of dopamine – or so I understand. This messes up co-ordination and can lead to loss of memory and indeed consciousness; but the most interesting effect, and the one for which alcohol is sometimes valued, is that it causes disinhibition. This allows us to relax and have a good time but may also encourage risky behaviour and lead to us saying things – in vino veritas – we wouldn’t normally let out.
Curiously, though, there’s no solid scientific support for the idea that alcohol causes disinhibition, and good evidence that alcohol is blamed for disinhibition it did not cause. One of the slippery things about the demon drink is that its effects are strongly conditioned by the drinkers expectations. It has been shown that people who merely thought they were consuming alcohol were disinhibited just as if they had been; while other studies have shown that risky sexual behaviour can actually be deterred in those who have had a few drinks, if the circumstances are right.
One piece of research suggests that meta-consciousness is impaired by alcohol; drink makes us less aware of our own mental state. But a popular and well-supported theory these days is that drinking causes ‘alcohol myopia’. On this theory, when we’re drunk we lose track of long-term and remote factors, while our immediate surroundings seem more salient. One useful aspect of the theory is that it explains the variability of the effects of alcohol. It may make remoter worries recede and so leave us feeling unjustifiably happy with ourselves; but if reminders of our problems are close while the long term looks more hopeful, the effect may be depressing. Apparently subjects who had the words ‘AIDS KILLS’ actually written on their arm were less likely to indulge in risky sex (I suspect it might kind of dent your chances of getting a casual partner, actually).
A merry and appropriately disinhibited Christmas to you!
(Bonus – some more recent papers on alcohol, providing more detail)