The Moderating Role of Baseline Oxytocin on Its Psychotherapy-facilitating Effects Among Patients With Eating Disorders

Introduction: Oxytocin (OT) is a nine-amino acid neuropeptide known to play a vital part in social behaviors and has also been found to be involved the social manifestations of mental illnesses, such as social manifestations and social cognition. it has been suggested that OT administration may serve as an add-on treatment for individuals with mental illnesses.

One group of patients affected by social are patients with eating disorders (EDs). Studies of OT administration among individuals with EDs have shown an inconsistent pattern of findings, which might be associated with the differential baseline level of OT dysregulation. Thus OT dosing needs to be optimized, while considering patients baseline OT levels prior to administration. Patients with ED are also known to have lower OT levels at baseline. It is possible that OT's administration will affect interpersonal behavior through the increase of lowered OT levels, thus leading to overall improvement of ED symptoms.

This study aims to examine the effects of OT administration among patients with EDs, while focusing on baseline OT levels and interpersonal abilities as potential moderators and/or mediators of its effects. The research addresses the following questions: (1) is OT administration associated with increased therapeutic gains among patients with ED? (2) what are the moderators and mediators of these effects, and specifically, do baseline levels of OT and baseline interpersonal abilities moderate these effects? (3) what is the mechanism underlying OT's therapeutic effects, and specifically do changes in interpersonal abilities and changes in OT levels serve a mediating role? Methods: This study aims to assess the differential effect of OT administration among patients with varying levels of baseline saliva OT and to explore the effects of optimizing frequency and dosage of administration of OT, based on baseline characteristics.

Participants: Female and male Individuals (N=90) with verified diagnosis of EDs, age 16 and above, will participate in at least four weeks of treatment at the EDs unit. Subjects will be recruited at the Teradion Eating Disorder Clinic, an outpatient unit in North Israel.

Procedure: Patients and caregivers will sign an informed consent form. Baseline saliva OT will be measured four times during consecutive days. At week 1 patients will be assessed for general distress, ED symptoms, cognitive rigidity, interpersonal abilities, as well as patients and therapists reported working alliance. At week 2 patients will be randomized at a ratio of 2:1 with 60 patients receiving OT and 30 receiving placebo. Patients will receive 24 IU of OT or placebo, once a week, prior to therapy sessions, for a period of 4 weeks. During these weeks (2-5), they will be assessed for levels of OT, general distress, interpersonal abilities, working alliance and cognitive rigidity. All measurements will be performed finally at week 6.

Novelty: This study is the first to assess the effectiveness of OT as an add-on for patients with EDs, during clinical treatment, as well as to explore modulators such as baseline OT levels, and mediators such as social abilities and cognitive rigidity, on the overall improvement of ED patients in therapy.