Thursday March 13 2014
Anorexia usually develops a few years after puberty
“A kiss to 'cure' anorexia: 'Love hormone' can help reduce sufferers' obsession with food and weight,” is the unsupported claim on the Mail Online.
This story involved the media’s favourite hormone, oxytocin which, depending on what pop-science source you read, has been dubbed as the “love”, “cuddle” or “kissing” hormone, as it is associated with intense emotions (both positive and negative).
The study found that 31 South Korean women with anorexia given an intranasal spray containing the hormone oxytocin paid less attention to images of food and fatter body shapes, but not to other weight-related images, 45 minutes later. Oxytocin had no effect on how much fruit juice the women could drink at the end of the study.
It is at best unclear whether these short term effects would lead to any improvement in the symptoms of anorexia. The results also may not be indicative of what would be found in a more diverse and larger group of people with anorexia.
This is far from convincing evidence that oxytocin could offer a treatment or “cure” for anorexia as implied by the headlines.
And even if oxytocin was effective, it doesn’t necessarily mean patients would use it.
From the current evidence, the mainstay of effective anorexia treatment involves psychological therapies.
Where did the story come from?
The study was carried out by researchers from Inje University and other universities in the Republic of Korea as well as King’s College London.
It was funded by the National Research Foundation of Korea and the Ministry of Education in the Republic of Korea, with the UK author being part funded by the National Institute for Health Research.
The study has been accepted for publication in the peer-reviewed journal Psychoneuroendocrinology.
A similar study, carried out by some of the same researchers, looked at the effect of oxytocin on attention to images of faces showing different emotions, has been published in the open access journal PLoS One.
This study also found some effect of oxytocin on attention to faces showing disgust and anger.
The media’s interest in this story may owe more to an interest in being able to use the phrase “love hormone” than the strength of the study findings, which the headlines over-state.
These findings are of a short term effect in a very small group of women on an outcome of, at best, unclear clinical relevance.
Any mention of a possible “cure” is arguably irresponsible journalism as it may give false hope to those who are concerned about family members or friends affected by anorexia.
What kind of research was this?
This was a randomised crossover study looking at the impact of an oxytocin nasal spray on response to food and weight related images in people with anorexia.
Oxytocin is a hormone released in high levels during childbirth. The drug is also released during sex, and is thought to be involved in helping people to form bonds.
Its role in these areas has led to it being called various things in the popular media, such as the “bonding hormone” or “love hormone”. However, there is also evidence that it is associated with less “cuddly” emotions such as envy and hostility to strangers.
The hormone also has effects on appetite, and fear and reward pathways in the brain, so the researchers wanted to test whether the hormone might have a beneficial effect on anorexia.
Drugs based on this hormone are already used medically to help induce labour, and it has been tested as a possible treatment in some mental health conditions, such as generalised anxiety disorder, postnatal depression and autistic spectrum disorder.
What did the research involve?
The researchers tested oxytocin in women with or without anorexia. They gave them a nasal spray containing the hormone or an inactive solution (placebo), and then tested their responses to pictures of food and weight related images and offered them a fruit drink. The researchers then assessed whether responses and drink consumption differed after oxcytocin or placebo, and if this depended on whether the women had anorexia or not.
The study enrolled 31 women with anorexia from South Korea, who were inpatients and outpatients at an early stage of treatment for the condition. The control group were 33 healthy female university student volunteers without anorexia.
The women all received oxytocin and placebo four to seven days apart. The order in which they received the drugs was randomly selected. The women self-administered a nasal spray containing either oxytocin or placebo, and the doctors and women did not know which the nasal spray contained.
Forty five minutes after administering the spray, the women took part in an experiment to test which of two alternative images gained their attention. They were shown paired photos on either side of a screen that either related to food and weight or an unrelated subject.
The food related images were:
- Food: High or low calorie foods, or neutral foods (not specified).
- Body shape: Parts of women’s bodies (such as thighs or stomach) of different shapes – some fatter, some slimmer, and some neutral (images of eyes or elbows that are not associated with body shape).
- Weight: Women weighing themselves, weighing scales or other weight related images.
Each of these photos was matched with an image expected to have a similar effect (positive, negative or neutral) but not relating to food, weight, or body shape. For example, this could include photos of kittens (positive), snakes (negative), or birds (neutral).
The images were displayed on either side of a screen for a second, then a symbol flashed on one side of the screen. The women had to press a button to identify which symbol they had seen as quickly as they could. The idea is that the women will get the question right more quickly when the symbol is on the side of the screen with the picture they were focusing on. So the experiment aimed to see whether they were focusing on the food and weight picture or the unrelated subject.
The implication being that if women with anorexia, who were in the oxytocin group focused less on food, weight and body shape related images, compared to placebo, then the hormone may be having a beneficial effect on their mind-set.
At the end of these tests, the women were asked to drink as much as they could of a 190ml carton of apple juice. The researchers compared the effects of oxytocin and placebo on their experiments, as well as various psychological measures taken during the day.
What were the basic results?
Women with anorexia and those without the condition showed similar responses to the images after placebo.
The women with anorexia paid less attention to the food images (negative, positive, or neutral) and negative shape images after the oxytocin nasal spray than after the placebo spray. Oxytocin did not have an effect on the women’s responses to the weight images.
The healthy women showed some slight differences in some responses to oxytocin to the women with anorexia, but these did not reach statistical significance.
Oxytocin had no effect on how much juice the women allowed themselves to drink at the end of the day.
How did the researchers interpret the results?
The researchers concluded that the effects they saw with oxytocin suggested that it could potentially reduce anorexia symptoms. They say that a study evaluating oxytocin as a treatment for anorexia is needed.
The study found that oxytocin nasal spray may reduce the short term attention to food and body shape images in women with anorexia.
This study was a small study including 31 South Korean women being treated for anorexia. While it showed some potential effect on the women’s attention to food and negative body shape images in the very short term, it is not clear whether this would result in an alleviation of their anorexia symptoms. Oxytocin did not have an impact the women’s consumption of a fruit juice at the end of a study, so any potential to affect (either in a negative or positive way) eating behaviour in these women remains unproven.
The small size and very select sample used in the study (women from one centre in South Korea) means the results may not be representative of the wider population with anorexia, particularly in other countries. Risk factors for anorexia are thought to be highly culturally specific and may vary from country to country.
Also, the study carried out multiple statistical tests, and this may mean that some are likely to find significant effects by chance.
This study presents far from convincing evidence that oxytocin could offer a treatment or “cure” from anorexia as implied by the headlines.
The current evidence suggests that the most effective treatments are talking therapies such as cognitive behavioural therapy.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.