title: Trait predictors of placebo responses in itch.
abstract: This study investigated trait predictors of placebo responses in the context of inflammatory skin reactions. This was a randomized, cross-over, experimental study using a deceptive placebo protocol. A healthy sample of volunteers (N = 48) completed online personality measures, then attended two laboratory sessions in which short-term inflammatory skin reactions were induced. One was a control session and the other the 'treatment' session in which a placebo cream was administered with the suggestion of a reduced skin reaction. A placebo response was defined as smaller skin reactions in control vs. treatment sessions. The traits ego resiliency and neuroticism were selected as possible predictors of placebo responses. Traits were selected in consideration of the two-faceted transactional model of placebo responsiveness and in light of empirical and psychometric considerations ego resiliency emerged as a consistent predictor of placebo responses in itch (p < .05). This is the first study to identify trait predictors of placebo responses in inflammatory skin reactions. Ego resiliency may typify greater placebo responsiveness; however, this may only be in certain contexts. Matching treatment approaches to bio-behavioural response tendencies may be useful clinically if the placebo component of traditional treatments can be enhanced.
authors.affiliation: a Faculty of Medical and Health Sciences, Department of Psychological Medicine , University of Auckland , Auckland , New Zealand.
authors.forename: Margot
authors.initials: M
authors.lastname: Darragh
authors.affiliation: a Faculty of Medical and Health Sciences, Department of Psychological Medicine , University of Auckland , Auckland , New Zealand.
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Booth
authors.affiliation: a Faculty of Medical and Health Sciences, Department of Psychological Medicine , University of Auckland , Auckland , New Zealand.
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Consedine
mesh_terms: D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D007206:Individuality; D008297:Male; D015990:Placebo Effect; D011537:Pruritus / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D063465:Skin Cream / Q000008:administration & dosage; D011795:Surveys and Questionnaires
keywords: Placebo effect; individual differences; inflammatory skin reactions; placebo personality; transactional model