title: Placebo/nocebo symptom reporting in a sham herbal supplement trial.
abstract: The present study examined reports of placebo and nocebo symptoms in a college sample. The study was presented under the guise of a clinical trial to evaluate the effectiveness of an over-the-counter herbal supplement intended to enhance cognitive performance. Participants were informed they would be receiving either an herbal supplement or a placebo, and each was provided with a mock list of possible beneficial and adverse effects of the "supplement." In fact, all participants received placebo. Symptoms were endorsed by a significant majority of participants following placebo ingestion. More important, results indicated that the few participants who believed they received an herbal supplement endorsed (via self-report) significantly more symptoms than those who believed they received a placebo. Neither anxiety nor social desirability was significantly related to symptom reporting. Results suggest that beliefs concerning treatment received may subsequently affect the degree of placebo response in a no-treatment group. Implications for clinical trials and future research are discussed.
authors.affiliation: University of North Texas, TX, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Link
authors.forename: Rob
authors.initials: R
authors.lastname: Haggard
authors.forename: Kimberly
authors.initials: K
authors.lastname: Kelly
authors.forename: Dan
authors.initials: D
authors.lastname: Forrer
mesh_terms: D000293:Adolescent; D000328:Adult; D001007:Anxiety / Q000523:psychology*; D003071:Cognition; D005260:Female; D006801:Humans; D008297:Male; D010919:Placebos; D028321:Plant Preparations / Q000009:adverse effects / Q000627:therapeutic use; D012928:Social Desirability
chemical_list: D010919:Placebos; D028321:Plant Preparations