The Role of Learning in Nocebo Hyperalgesia

Summary

Nocebo effects are adverse effects induced by patients' expectations. Nocebo effects on pain may underlie several clinical conditions, such as chronic pain. These effects can be learned via classical conditioning mechanisms. In the lab, nocebo effects are commonly studied via conditioning with continuous reinforcement (CRF) during which 100 percent of unconditioned pain stimuli are paired to conditioned stimuli (i.e., the activation of a mock medical device). Partial reinforcement (PRF) provides a more uncertain pairing during conditioning, where less than 100 percent of unconditioned pain stimuli are paired to conditioned stimuli. This method provides a potentially more clinically relevant learning platform to study how nocebo effects on pain are induced. In this study, the efficacy of conditioning with PRF, CRF, and sham-conditioning in inducing nocebo effects on pain will be compared. Furthermore, a counterconditioning method will be compared to an extinction method for the attenuation of nocebo effects on pain. Given the relevance of nocebo effects for patients, it is important to ascertain effective \& clinically relevant methods to understand how nocebo effects may be formed and attenuated. This study is conducted by Leiden University.

Conditions

• Nocebo Effects
• Hyperalgesia
• Chronic Pain
• Pain Syndrome

Interventions

BEHAVIORAL

Conditioning with partial reinforcement

Conditioning with partial reinforcement (PRF) provides an uncertain pairing of unconditioned high pain stimuli and conditioned stimuli (i.e., on-screen messages signaling the activation of a mock medical device). During PRF only 70 percent of unconditioned stimuli are paired to conditioned stimuli. Pain of only moderate intensity is used for control stimuli that are paired to the deactivation of the mock device and are also used in the 30 percent of unreinforced trials.

BEHAVIORAL

Conditioning with continuous reinforcement

During conditioning with continuous reinforcement (CRF) unconditioned high pain stimuli are paired to conditioned stimuli (i.e., on-screen messages signaling the activation of a mock medical device) in 100 percent of conditioning trials. Pain of only moderate intensity is used for control stimuli that are paired to the deactivation of the mock device.

BEHAVIORAL

Counterconditioning

During counterconditioning, the previously conditioned nocebo effects on pain are attenuated by pairing the same conditioned stimuli (i.e., on-screen messages signaling the activation of a mock medical device) to thermal pain stimuli of low intensity.

BEHAVIORAL

Extinction

During extinction, the previously conditioned nocebo effects on pain are attenuated by pairing the same conditioned stimuli (i.e., on-screen messages signaling the activation of a mock medical device) only to control stimuli of moderate intensity (previously paired to the deactivation of the mock device).

BEHAVIORAL

Sham Conditioning

In the sham group, participants receive different instructions (namely, that the activation of the device is not expected to affect their pain sensitivity). Additionally, during sham conditioning unconditioned stimuli are not consistently paired to conditioned stimuli, thereby preventing the formation of an association between high pain stimuli and the activation of the mock medical device. In the attenuation phase participants undergo an extinction procedure.

Sponsors & Collaborators

• Universiteit Leiden

  collaborator OTHER

• Leiden University Medical Center

  lead OTHER

Principal Investigators

• Andrea WM Evers, Prof. Dr. · Leiden University Medical Center

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

DOUBLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

35 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2018-09-20

Primary Completion

2019-04-30

Completion

2019-04-30

Countries

• Netherlands

Study Locations