Would you push someone in front of a train if that would save five others? Probably not if you’re on an antidepressant that raises your serotonin levels. Increased serotonin makes us less willing to hurt or punish other people, even if it’s for the “greater good”, a study has found.
To test the effect of antidepressants on moral judgements, Molly Crockett and her team at the University of Cambridge presented 24 healthy volunteers with a moral dilemma while they were under the influence of the antidepressant citalopram – a selective serotonin reuptake inhibitor (SSRI), which increases brain serotonin levels.
The participants given citalopram were about 10 per cent less willing to inflict harm on someone in order to benefit others compared with those given a placebo.
The volunteers also played a game in which they were asked to accept or decline another player’s offer of a share of a sum of money. If they accepted the offer, each player kept their share. If they refused, both players were left empty-handed.
People with raised levels of serotonin were more likely to accept a stingy offer, rather than punishing the other player’s greed by refusing it.
Crockett points out that antidepressants are the most widely prescribed class of drugs in the US and that it is therefore important to investigate their effects on users’ social behaviour and moral judgement.
Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1009396107
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