The Effect of Oxytocin on Placebo Analgesia: an Experimental Study in Healthy Volunteers

Placebo responses contribute to medical treatment outcome. The purpose of this study is to determine whether a single intranasal application of oxytocin can increase the placebo response in an experimental model of placebo analgesia in healthy volunteers.

The rationale to study the effects of oxytocin on placebo analgesia is based on previous studies showing that oxytocin fosters processes such as empathy, trust and social learning, which are key elements of the patient-physician relationship that is pivotal to placebo responses. In this experimental mechanisms study we used oxytocin as a tool to modulate these factors.

Placebo analgesia is induced verbal instruction. Therefore two identically looking placebo ointments were applied to two sites of the participants' volar forearm. The ointments were introduced as a local anesthetic that could reduce or even abolish pain (placebo) and a control cream (control), respectively.

Inclusion criteria

• healthy volunteers, male and female
• being German-speaking
• Agreeing to participate, verified by completion of informed consent

Exclusion criteria

• acute or chronic pain condition
• use of any concomitant medication except contraceptives
• currently pregnant (verified by urine pregnancy test) or lactating
• major mental disorder
• Inability to comply with the study procedures
• abnormal pain sensitivity as indicated by pain threshold
• alcohol intake within last 24 hours