title: Are Children the Better Placebo Analgesia Responders? An Experimental Approach.
abstract: There is little information regarding changes in placebo responsiveness with age, although first predictors of placebo responders such as psychological and physiological processes have been identified. Reviews and meta-analyses indicate that placebo response rates in randomized controlled trials (RCTs) are higher in children and adolescents compared with adults. As these studies cannot control for age-dependent differences in the natural course of the disease, biases might contribute to different placebo rates in RCTs. To avoid these biases, this study investigated age-related differences in placebo responsiveness between children and adults in a well-established experimental model of placebo analgesia combining classic conditioning and expectation. Our data confirm placebo analgesic responses in children, which did not differ in magnitude from those of adults. The influence of previous experience on subsequent treatment outcome was stronger in children than in adults, indicating an increased relevance of learning processes for treatment outcomes in children. Further studies are needed to understand the influence of treatment-related learning processes in children and adolescents, which might critically determine treatment responsiveness during adulthood.
  
  
  CONCLUSIONS
  This study is the first to experimentally explore placebo analgesia and influences of previous experience on placebo responses in children compared with adults. We found comparable placebo responses in both groups and an increased relevance of learning processes for treatment outcomes in children.
authors.affiliation: Department of Neurology, University Hospital Essen, Essen, Germany; Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. Electronic address: n.wrobel@uke.de.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Wrobel
authors.affiliation: Department of System Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Tahmine
authors.initials: T
authors.lastname: Fadai
authors.affiliation: Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Department of System Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Sprenger
authors.affiliation: Department of Child and Adolescent Psychiatry and Psychotherapy, University of Duisburg-Essen, Essen, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Hebebrand
authors.affiliation: Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom; Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom.
authors.forename: Katja
authors.initials: K
authors.lastname: Wiech
authors.affiliation: Department of Neurology, University Hospital Essen, Essen, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Bingel
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging; D000698:Analgesia / Q000379:methods*; D000704:Analysis of Variance; D002648:Child; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000523:psychology* / Q000628:therapy*; D008297:Male; D010147:Pain Measurement; D017288:Pain Threshold / Q000523:psychology; D015990:Placebo Effect; D055815:Young Adult
keywords: Placebo analgesia; adolescent; adults; children; experimental pain; learning; placebo effect