Science Interviews


Fri, 6th May 2016

Myth: The cuddle chemical

Dr Kat Arney, Naked Scientists

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This week, Kat Arney has been getting up close and personal with the so-called Huggingďcuddle chemicalĒ.

Kat - Itís been described as the Ďhormone of loveí, and even Ďnatureís love glueí - a simple chemical that bonds mothers to their babies, is said to be responsible for keeping couples loved up, and has even been claimed to be able to make us all more generous, trustworthy and compassionate. Weíre talking about the molecule oxytocin, and there are research studies of varying size and quality showing that a lack of it might be to blame for problems such as alcohol or drug addiction, while a quick sniff of the stuff can keep men faithful, make you feel more sociable, and even help you lose weight.

But - sadly for anyone whoís hoping that a simple squirt of oxytocin might be the solution to all their problems and help them snare the subject of their dreams - itís a bit more complicated than that.

Back in 2005, a trio of researchers published a paper in the journal Nature entitled ďOxytocin increases trust in humansĒ, based on a small research study asking volunteers to play a game in which they had to trust each other, and were also given sniffs of the chemical. And while thereís no doubt that oxytocin is a very interesting biological molecule, the full picture is more murky than moral.

Oxytocin is made in a part of the brain called the hypothalamus, and transported out across the whole body. Beyond doubt, we know that it plays important roles in birth, breastfeeding and parental bonding. And we also know that itís released in the brain and elsewhere in the body by non-pregnant people. But whatís a bit more tricky to prove is exactly what itís doing, if and how it can change human behaviour, and whether itís acting alone or in concert with all the other chemicals and cues that feed into our thoughts, feelings and actions.

So what do we know?

Some of the strongest evidence for a role for oxytocin in romance doesnít come from humans at all, but from a certain species of prairie vole, Microtus ochrogaster, that pair bonds for life. And giving normally non-monogamous vole species doses of oxytocin and another so-called happy hormone, vasopression, switch them into monogamous behaviour. But, importantly, itís not enough just to dose voles with drugs to make them monogamous lovers - they need to spend time together too, at least six hours of hanging out together to feel bonded. But humans arenít voles, so what else do we know about how oxytocin might affect our brains and behaviours.

One small study of less than 100 participants, published in the Journal of Neuroscience, suggested that a sniff of oxytocin made men in long-term monogamous relationships keep a greater distance from an attractive woman (who wasnít their partner) than single ones.

Oxytocin has also been found to improve peopleís perception of their own personality, in turn making them more outgoing in social situations - again in a small study of in a small study of 100 people. Itís been shown to counteract the feelings of drunkenness induced by alcohol and maybe even cut cravings for booze, and has also been shown to play a role in addiction. Furthermore, a preliminary report from a study of just 10 overweight or obese men reported at a meeting in April this year suggests that a sniff of oxytocin might help to improve their self-control around food.

Itís certainly not all good news though. Giving people oxytocin can actually strengthen bad memories and increase anxiety, or make people oversensitive to the emotions of others.

Meanwhile a 2011 study with 280 Dutch volunteers showed that giving them oxytocin encouraged them to feel more negatively towards those perceived as outsiders, potentially encouraging racism, xenophobia and prejudice. Itís also been linked with an increase in dishonesty in men, as well as other negatively-perceived feelings such as envy and schadenfreude. So much for the Ďlove chemicalí, if it only applies to loving people like youÖ

Another study showed that giving couples sniffs of oxytocin could help boost communication between them. Itís clear that communication is key to good relationships, and even just talking with and touching each other can lead to oxytocin release in the brain. But can adding oxytocin jump-start the communication process and salvage a relationship on the skids? We donít know, because human love-lives are far trickier to unravel in the lab than simple cells or organisms.

There are also big differences between people that affect how they respond to oxytocin in different circumstances. Some of them are down to personality, others are genetic, and yet more come down to sex - men and women respond differently to the hormone.

Regardless of the conflicting scientific evidence, oxytocinís reputation as the love drug is problematic, because the reporting about its loved-up effects has now meant that itís possible to buy oxytocin on the internet, even though thereís no good evidence that itís effective, safe for long-term use, or that itís even what it says on the bottle.

So what does oxytocin actually do, if it isnít fair to call it the Ďlove drugí or Ďcuddle chemicalí? And thereís certainly no good evidence that giving people a whiff of oxytocin will make them fall in love, stop them from straying or make the world a better place - thatís an awful lot to ask of a single molecule in the molecular maelstrom of our bodies and brains. Itís probably safest just to say that itís a molecule that has an influence on our social interactions, but exactly how depends on who we are and our circumstances. And thatís not something a quick squirt from a bottle of oxytocin can change, however much you want to believe the hormone hype.


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