Placebo analgesia is not due to compliance or habituation: EEG and behavioural evidence.
This study was designed to resolve whether experimental placebo responses are due to either increased compliance or habituation. We stimulated both forearms and recorded laser-evoked potentials from 18 healthy volunteers treated on one arm with a sham analgesic cream and an inactive cream on the other (treatment group), and 13 volunteers with an inactive cream on both arms (controls). The treatment group showed a significant reduction in the pain ratings and laser-evoked potentials with both the sham and inactive creams. The control group showed no evidence of habituation to the laser stimulus. The results indicate that the reduction in pain during experimental placebo response is unlikely to be due to sensory habituation or compliance with the experimental instructions.
Watson
Alison
A
Human Pain Research Group, University of Manchester, Institute of Neuroscience, Hope Hospital, Salford, UK. alison.watson@manchester.ac.uk
El-Deredy
Wael
W
Vogt
Brent A
BA
Jones
Anthony K P
AK
D000328:Adult; D000698:Analgesia; D001931:Brain Mapping; D004311:Double-Blind Method; D004569:Electroencephalography; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D005260:Female; D005542:Forearm / Q000294:innervation; D006185:Habituation, Psychophysiologic; D006801:Humans; D007834:Lasers / Q000009:adverse effects; D008297:Male; D010146:Pain / Q000188:drug therapy* / Q000209:etiology; D010147:Pain Measurement / Q000379:methods; D010349:Patient Compliance; D010919:Placebos / Q000627:therapeutic use*
D010919:Placebos