Intranasal Oxytocin Diminishes Food Intake, Improves Social Cognition among Bulimic Patients

The hormone had little or no effect on normal controls or patients with anorexia nervosa.

Reprinted from Eating Disorders Review
November/December Volume 26, Number 6
©2015 IAEDP

Oxytocin (Greek for "quick birth") is a mammalian hormone that acts as a neurotransmitter in the brain. Because oxytocin impacts social behavior, appetite, anxiety, and stress, researchers believe oxytocin may also be involved in the pathophysiology of eating disorders.

There is some prior evidence for this. Intranasal administration of oxytocin leads to changes that may be important in AN; for example, an AN patient's attention to food and body image stimuli is reduced by oxytocin administration. Fewer studies have examined the oxytocin system among people with bulimia nervosa (BN), although some of the features of BN or binge eating disorder (BED) also hint of possible dysfunction in the oxytocin systems. For example, the hormone is an important peptide for body weight regulation. Animal studies have added information about the complex effects of oxytocin, particularly its ability to inhibit the appetite for sugars and carbohydrates. Similarly, in humans, when oxytocin was administered to a group of obese men, food intake was reduced.

A study of oxytocin's effect on appetite and emotions

A recent Korean study of 102 women (35 patients with AN, 34 with BN, and 33 healthy controls) tested the effects of a single dose of oxytocin on appetite and emotion recognition. At Seoul Paik Hospital, Seoul, South Korea, neuropsychiatrist Youl-Ri Kim and colleagues designed a double-blind, single-dose, placebo-controlled cross-over study to test the effects of the hormone (PLoS ONE. 10 (9)e13514.9. doi:10.1371/journal.pone.0137514).

Subjects and controls received a single dose (40 IU) of intranasal oxytocin or placebo, and then performed a computerized emotion recognition task, followed by an apple juice drink 90 minutes after the intranasal dose. All subjects' food intake was then recorded for 24 hours after the test. 

 Patients with eating disorders were given meal plans with fixed-size portions during the time of the experiment, to mitigate the drug's effect on calories consumed over the 24 hours before testing. Patients with AN did not have any direct support for eating during the 24 hours after the experiments on the inpatient ward, while patients with BN had meal plans focused on preventing binge eating and purging. The healthy controls were instructed to continue their regular diet during the 24 hours after the experiment.

Some effects were noted among patients with BN

The oxytocin dose produced no significant change in appetite among the healthy controls, but oxytocin modestly diminished 24-hour calorie intake in patients with BN. Oxytocin produced a small increase in emotion recognition sensitivity in healthy controls and in the patients with BN. In contrast, among the patients with AN, oxytocin had no effect on the patients' emotional recognition sensitivity or on food consumption. 

These results are interesting, and emphasize the complex effects of oxytocin on behavior, as well as the potential role of ED diagnosis (for symptoms) in determining response to oxytocin. One potential study limitation not noted by the authors is that subjects received a single dose; perhaps ongoing administration would have made effects last longer.