Some temperament characteristics of personality seem to be modulated by oxytocin. Patients suffering from eating disorders (EDs) display aberrant personality traits.

We investigated the relationships between plasma oxytocin levels and personality dimensions of patients with anorexia nervosa (AN) and bulimia nervosa (BN) and compared them to those of healthy controls.

Plasma oxytocin levels were measured in 23 women with AN, 27 women with BN and 19 healthy controls and assessed their personality traits by means of the Cloninger's Temperament and Character Inventory-Revised (TCI-R).

AN patients showed plasma levels of the hormone significantly lower than BN and healthy controls. In healthy women, plasma oxytocin levels resulted significantly correlated negatively with novelty seeking scores and positively with both harm avoidance (HA) scores and the attachment subscale scores of the reward dependence: these correlations explained 82% of the variability in circulating oxytocin. In BN patients, plasma oxytocin resulted negatively correlated with HA, whereas no significant correlations emerged in AN patients.

These findings confirm a dysregulation of oxytocin secretion in AN but not in BN and show, for the first time, that the association of circulating oxytocin to patients’ temperament traits is totally lost in underweight patients with AN and partially lost or even inverted in women with BN. These findings suggest a role of oxytocin in certain deranged behaviours of ED patients, which are influenced by the subjects’ personality traits.

The authors have not supplied their declaration of competing interest.