Science - June 9, 2005

Commentary / Hormonal trust

Swindlers watch out! Science magazine Nature reports that students who have sniffed a small amount of the hormone oxytocin are more inclined to trust other people. According to the Swiss researchers, oxytocin is responsible for us lowering our guard against strangers. This would suggest that it is easy for evil wishers to manipulate people. Or is there no cause for alarm?

Dr Katja Teerds of the Human and Animal Physiology group:
‘This research was done by the Institute for Empirical Research in Economics in Zurich. They are behavioural scientists, so more on the social side. I don’t think an endocrinologist was involved. The Swiss gave their subjects, recruited from first-year university students, 24 international units of the hormone through a nose spray.

‘Substances administered via the nose are absorbed very quickly. The tiny blood vessels in the nose membrane can transport the substances to the brain within a few minutes. After administering the hormone the researchers observed their subjects in a kind of role-play, and apparently the students showed more trust than before they had sniffed oxytocin.

‘Trust is good, say the researchers. ‘Trust is vital for friendship, love, families and organisations, and plays a key role in the economy and politics. If trade partners do not trust each other, then market relations collapse.’

‘Hmm, this is all very socio. I cannot say a lot about the research, as I’m not a social scientist. I’m an endocrinologist. The researchers say that they have based their work on animal studies, in which for example rats receive direct injections of oxytocin in their brains.

‘Oxytocin is released in large quantities just before giving birth. Women whose labour is not progressing rapidly enough are sometimes given the hormone. Here on PubMed I can see a study in which researchers injected lactating rats with oxytocin. Lactating rats are aggressive towards male rats to protect their young, but in this study the aggression decreased as a result of the oxytocin. The hormone affects parts of the brain that are linked to sexuality and aggression, feelings that are close related to each other.

‘The problem that I have with this kind of study is that the reasoning is simplistic. More oxytocin, more trust. But endocrinology is more complex than that. Endocrinology is not just a question of administering a hormone and looking at the effect it has. Oxytocin, for example, plays a role in aggression, but serotonin and testosterone do as well. Hormone A can also influence the production of hormone B. Administering hormone A often reduces the manufacture of the same hormone. If you introduce a hormone from outside you disturb a balance and the body reacts to this. That is why externally administered hormones nearly always have side effects.

‘For this reason the researchers omitted subjects that used medicines or had a psychiatric history from their study. Oxytocin could exacerbate the symptoms of depression in people with depressive tendencies.

‘This research does not give much indication of the complexity. Once again though, I am an endocrinologist and not a social behaviourist. But I would not like to draw big conclusions from this piece of research.’ / WK