Universiteit Leiden

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Research project

Placebo research: Pain and itch

The major aim is to determine the role of expectancy mechanisms (e.g., verbal suggestion, classical conditioning, and imagery) in placebo and nocebo effects on different psychical sensations (e.g., pain, itch, and fatigue) and how these expectancy mechanisms can be used to optimize health.

NWO Vidi Grant

For highly prevalent chronic pain and itch conditions, treatment effects are usually modest and vary strongly between patients. Expectancy mechanisms are supposed to contribute to the treatment variability. A validated paradigm to experimentally study expectancy mechanisms is the placebo design, with particular evidence in the area of pain. Expectancy mechanisms have been shown to apply even more strongly to physical symptoms of itch. However, the psychophysiological mechanisms are poorly understood.

The research program focuses on the primary role of expectancies in placebo mechanisms and investigates related psychophysiological mechanisms to clarify 1) placebo and nocebo effects for pain and itch, 2) the causal role of expectancy learning and cognitive schemas of placebo-related expectancies, 3) their short-term and longer-term psychophysiological consequences, and 4) training of these expectancy mechanisms.

The program provides a substantial contribution to psychophysiological expectancy models and to therapeutic applications for a highly prevalent health problem, the variability in psychological and pharmacological treatment outcomes (for further placebo projects, see research program ‘Placebo research: Training of the immune and endocrine system’).

This NWO Vidi Grant project is divided into two PhD projects: 

1. Induction of expectancy mechanisms underlying placebo and nocebo effects applied to physical sensations

Placebo and nocebo effects (expectation of symptom reduction and induction) for both pain and itch are induced and trained in healthy controls and patients, using validated and innovative procedures of classical conditioning and placebo-related outcome expectancies. This project examines the mechanisms underlying placebo and nocebo effects with regard to physical sensations, such as itch. Expectancy learning mechanisms of verbal suggestions and conditioning are investigated with regard to inducing and counteracting placebo and nocebo effects. Additionally, the role of cognitive schemas of placebo-related outcome expectancies, and individual differences in placebo responding are investigated.

Supervisors Leiden University: Prof.dr. Andrea Evers & Dr. Antoinette van Laarhoven
PhD student: Danielle Bartels


2. Training of expectancy mechanisms underlying placebo and nocebo effects applied to physical sensations

This project focuses on the comparative and additive effects of various expectancy trainings including imagery and verbal suggestions on physical sensations, such as pain, itch, and fatigue. The effects of expectations on both self-reported and psychophysiological outcomes are examined.

Finished PhD project
These studies were conducted in the context of the PhD project of Kaya Peerdeman, with Prof. dr. Andrea Evers as the first promotor, & Dr. Antoinette van Laarhoven as co-promotor.

This research program is part of the Research Group Psychoneurobiology of Health and Disease (www.andreaevers.nl

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