title: Placebo effects in idiopathic and neuropathic pain conditions.
abstract: The magnitude of placebo analgesia effect appears to be large in chronic pain patients experiencing hyperalgesic states. So far, placebo effects have primarily been investigated in idiopathic pain conditions, such as irritable bowel pain syndrome, but more recently they have also been investigated in neuropathic pain patients, in which the underlying nerve injury is known. Expected pain levels and emotional feelings are central to placebo effects in both types of pain. They appear to help patients to engage in a mindset for pain relief and activate the pain-modulating system. Furthermore, expectations, emotional feelings, and the experience of pain seem to interact over time, thereby maintaining or enhancing the pain-relieving effect. Expectations and emotional feelings also contribute to the effect of active drugs, and recent studies indicate that drug effects and placebo effects interact in ways that may complicate the interpretations of the findings from clinical trials. It is suggested that expectations and emotional feelings may act as additional or alternative measures in the testing of new pharmacological agents, thereby improving the understanding of the interaction between pharmacological effects and placebo effects, which may have far-reaching implications for research and clinical practice.
authors.affiliation: Department of Psychology and Behavioral Sciences, School of Business and Social Sciences, Aarhus University, Aarhus, Denmark, lenevase@psy.au.dk.
authors.forename: Lene
authors.initials: L
authors.lastname: Vase
authors.forename: Gitte Laue
authors.initials: GL
authors.lastname: Petersen
authors.forename: Karen
authors.initials: K
authors.lastname: Lund
mesh_terms: D004644:Emotions; D006801:Humans; D009437:Neuralgia / Q000188:drug therapy / Q000523:psychology*; D064786:Nocebo Effect; D010146:Pain / Q000188:drug therapy / Q000523:psychology*; D015990:Placebo Effect; D016032:Randomized Controlled Trials as Topic