Oxytocin changed responses to food, emotions in anorexia nervosa

Two recent studies showed that doses of the hormone oxytocin modified attentional responses to emotional stimuli in patients with anorexia nervosa, potentially providing new treatment options for patients diagnosed with the disorder.

Patients with anorexia nervosa who were given intranasal oxytocin exhibited reduced fixations on high-calorie foods and larger body shapes; additionally, the oxytocin moderated study participants’ avoidant reactions to images of faces showing negative emotions.

Janet Treasure

Janet Treasure, FRCP, FRCPsych, PhD, and Valentina Cardi, PhD, of King’s College London, worked with researchers from Korea to construct two trials that compared the effects of intranasal oxytocin with a placebo when study participants viewed images that researchers predicted would act as attentional stimuli.

Researchers cited previous studies that noted oxytocin’s efficacy in increasing sensitivity to emotive facial expressions. Earlier research also provided evidence for low and abnormal oxytocin levels in patients with anorexia nervosa, especially when the body is in starvation mode.

“Patients with anorexia have a range of social difficulties which often start in their early teenage years, before the onset of the illness. These social problems, which can result in isolation, may be important in understanding both the onset and maintenance of anorexia,” Treasure said in a press release. “By using oxytocin as a potential treatment for anorexia, we are focusing on some of these underlying problems we see in patients.”

Food, Body Shape Stimuli

The double-blind, placebo-controlled study, published in Psychoneuroendocrinology, examined the effect of oxytocin on attentional processes related to eating, body shape and weight in patients with anorexia nervosa. The study included 64 female participants, 31 of whom were identified as having anorexia nervosa based on a self-report questionnaire. Participants also responded to a self-report questionnaire about autism spectrum behaviors.

Participants self-administered 40 IU of oxytocin via an intranasal spray. Each study participant received a dose of the oxytocin spray before responding to a visual probe detection test. On a different occasion, participants inhaled a placebo spray before responding to a similar visual test.

Participants responded to visual stimuli including photos of food, which researchers rated as positive, neutral or negative. Participants were also shown positive, neutral and negative images related to body shape and fat, including close-ups of body parts and images of women weighing themselves, compared with control images unrelated to body weight.

Researchers measured participants’ attentional biases by the response time it took a participant to press a key in response to an image on the screen. A quicker response under target circumstances was interpreted as a response to a threat.

Statistical analysis demonstrated that the oxytocin doses showed significant reductions in negative attentional biases toward eating-related stimuli (P=.030) and toward negative shape stimuli (P=.015) in the anorexia nervosa group. Oxytocin was most helpful in easing negative reactions to food and body fat stimuli for patients who displayed more communication traits associated with autism spectrum conditions, according to data.

“Our findings suggest the potential for oxytocin nasal spray to reduce anorexia nervosa symptoms. A future evaluation of oxytocin as a treatment for anorexia nervosa is merited,” the researchers wrote.

Social Responses

The second study used data gathered from the same participants and examined the effect of oxytocin when participants reacted to photographs of different facial expressions including anger, disgust and happiness. Participants were given the same dosage of oxytocin spray identified in the first study and were asked to perform a visual probe detection task. They also completed the task on a different occasion after administration of a placebo spray.

Photographs from a clinically validated collection of facial expressions showed adult faces expressing 15 positive (happy) and 30 negative (angry and disgusted) emotions, along with images of the same faces wearing a neutral expression.

Data from statistical analysis showed that oxytocin moderately reduced attentional bias reactions to disgusted facial expressions in both the anorexia nervosa group and the control group. After administration of placebo, participants showed avoidant behavior toward angry expressions and the control group showed vigilance; both of these responses were moderated by oxytocin, producing greater vigilance to angry expressions in the anorexia nervosa group and lowering vigilance in the control group. Happy expressions did not did elicit changes in response after oxytocin or placebo exposure for both groups.

Because oxytocin raised vigilance to anger in the anorexia nervosa group and lowered vigilance to anger in the control group, researchers saw an essential difference in how the study groups processed some negative emotions.

“We conclude that patients with anorexia nervosa appear to use different strategies/circuits to emotionally process anger from their healthy counterparts,” researchers said.

For more information:

Kim Y-R. Psychoneuroendocrinology. 2014;doi:10.1016/S0140-6736(13)62629-X.

Kim Y-R. PLoS ONE. 2014; doi:10.1371/journal.pone.0090721

Disclosure: The researchers report no relevant financial disclosures.