Oxytocin Studied as a Possible Treatment for Anorexia Nervosa

Results of a series of pilot studies led by Drs. Janet Treasure, of King’s College, London, and Youl-Ri Kim, of Seoul’s Paik Hospital, are beginning to tease out the potential roles of oxytocin, sometimes called “the love hormone,” and its receptor to see if the hormone might provide a new treatment for anorexia nervosa (Plos One. March 2014, e90721).

Why oxytocin?

Oxytocin (from the Greek, “quick birth”) is a hormone produced by the hypothalamus that is stored by and released from the pituitary gland. Oxytocin is released naturally during social recognition, bonding, sex, childbirth, and breastfeeding, and in its synthetic form has been tested as a treatment for numerous psychiatric disorders. Because it is digested in the gastrointestinal tract when taken orally, oxytocin is usually administered as a nasal spray.

Problems in social and emotional development have been linked to the oxytocin systems, and abnormalities in the oxytocin receptor gene have been linked to empathy, trust, and maternal behavior, stress reduction, anxiety and depression. As Dr. Kim and his colleagues have noted, patients with AN experience a range of social difficulties that sometimes occur before the onset of AN. The researchers theorize that oxytocin function might explain some of these changes. Other authors have reported that patients with AN have low cerebrospinal fluid oxytocin levels, and that greater abnormalities are reported as eating disorders symptoms worsen.

The authors designed two studies to chart the effects of oxytocin. In the first double-blind, placebo-controlled study, 31 women with AN and 33 healthy controls were given either a dose of oxytocin, delivered in a nasal spray, or a placebo. The study participants then viewed sequences of images relating to food (high- and low-calorie foods), body shape (fat and thin), and weight, as shown on scales. When the images flashed across the screen, the researchers measured how quickly the women identified the individual images. The women also completed several self-report questionnaires, including the Eating Disorder Examination Questionnaire (EDE-Q). After testing was complete, the women were offered apple juice and asked to drink as much as they could. Receiving oxytocin diminished the degree to which participants focused on eating and shape stimuli, even though the intake of juice was unchanged.

Oxytocin may moderate social difficulties

In the second study, which included the same group of women, a similar test was done before and after oxytocin or placebo was given. However, this time the researchers observed the women’s reactions to facial expressions, such as anger, disgust, or happiness. After receiving a dose of oxytocin, patients with AN were less likely to focus on the expressions of ‘disgust’ and were less likely to avoid angry faces; instead, they became more vigilant to the angry faces.

In a separate survey, the authors also examined the methylation status of the oxytocin receptor gene (OXTR) in patients with AN (PLoS One 9:e88673 doi:10.1371). Methylation is a common epigenetic mechanism that diminishes gene expression. The authors studied average methylation levels between the two groups of women (15 with AN and 46 healthy controls). The researchers found that individuals with AN had methylation at 5 of 6 sites within the OXTR gene. Normal healthy women had low or intermediate levels of methylation. The authors suggest that epigenetic mechanisms in the OXTR gene may play a role in the pathophysiology of AN.