title: Understanding the placebo effect. Part 2: underlying psychological & neurobiological processes.
abstract: Placebo and nocebo effects are interesting and complex phenomena. In this article, I discuss some findings about the psychological and neurobiological processes that may underlie these effects on the basis of studies of pain, Parkinson's disease, and depression. From a psychological perspective, expectancy and conditioning theories have been used to explain placebo and nocebo effects. These psychological processes may be translated into physiological effects through overlapping brain circuits that are important for cognitive information processing, analgesia, and reward expectations. These brain circuits may represent a fundamentally important common underlying pathway that mediates placebo and nocebo effects in many conditions. Understanding these effects is important for designing clinical treatment studies and interpreting their results and is highly relevant for clinical practices.
authors.affiliation: University of Pittsburgh School of Medicine, Western Psychiatric Institute and Clinic, Pittsburgh, PA 15213, USA. HowlandRH@upmc.edu
authors.forename: Robert H
authors.initials: RH
authors.lastname: Howland
mesh_terms: D001294:Attitude to Health; D001923:Brain Chemistry; D002986:Clinical Trials as Topic / Q000451:nursing; D003071:Cognition; D003213:Conditioning, Psychological; D003863:Depression / Q000188:drug therapy / Q000523:psychology; D006801:Humans; D008606:Mental Processes; D009446:Neurobiology; D024802:Nurse's Role; D010146:Pain / Q000188:drug therapy / Q000523:psychology; D010300:Parkinson Disease / Q000188:drug therapy / Q000523:psychology; D015990:Placebo Effect; D011568:Psychiatric Nursing; D011600:Psychopharmacology; D012107:Research Design; D012201:Reward; D012718:Set, Psychology; D016896:Treatment Outcome