Original Abstract of :
Placebo Effects on Gastric Motility – Earlier Results Can only Partially Be Replicated

The specific effect of placebo therapies on organs has rarely been studied using experimental approaches. However, as early as 1964, Sternbach had reported that healthy subjects (n= 6) show increased stomach activity (compared to control condition) following the administration of a presumed stimulant and decreased activity when the placebo was presumed to be a relaxant. We tried to replicate this study as closely as possible by using cutaneous electrogastrography (EGG). In three randomized conditions, 18 healthy volunteers (ages 21-34) received a lactose pill. They were told to receive a drug that either stimulates or relaxes stomach activity, or has no effect (stimulant, relaxant, or control condition). Stomach activity was recorded during 30 minutes before and 30 minutes after placebo administration. Raw EGG-signals were bandpass-filtered and half periods of gastric slow waves determined as mean intervals between successive zero-crossings. The averages (n= 17) of the half periods increased significantly by 0.22 sec for the stimulant condition and decreased by 0.12 sec for both, the relaxant and the control condition, when compared to the corresponding pre-intervention values (single-factor ANOVA, p< 0.05). The pair wise Bonferroni/Dunn post hoc test indicated significant (p< 0.05) differences between stimulant and relaxant as well as stimulant and control conditions. Thus, compared to the control condition, the dominant frequency of the gastric slow wave decreased for the stimulant condition but did not change for the relaxant condition. Although our results generally confirm Sternbach’s report of placebos affecting gastric slow wave activity, we found such changes only in the stimulant condition, and in the direction opposite to Sternbach’s findings.
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Original Abstract of :
Placebo Effects on Gastric Slow Wave Frequency

The susceptibility of inner organs to placebo administration and the issue of response specificity have rarely been addressed experimentally. We have attempted to induce placebo effects on gastric motility while measuring the electrogastrogram (EGG) and the ECG at the same time. In three randomized conditions 18 volunteers received a lactose pill pretending to either stimulate, or relax stomach activity, or have no effect (stimulant, relaxant, or control condition). Recordings were taken during 30 min before and 30 min after placebo administration. The frequency of the dominant spectral component of the EGG was estimated by using the mean intervals between successive zero-crossings of the suitably band-filtered raw EGG. In addition, relative spectral power within the normal frequency band of the EGG was calculated. As cardiac autonomic measures, heart rate (HR) and respiratory sinus arrhythmia (RSA) were derived from the ECG. Change scores of each variable were tested using 2 x 3 ( order x  condition) ANOVAs. There was a significant main effect of condition on EGG frequency, but not on 3/min power of EGG, on HR, or RSA. Compared to the control condition, EGG frequency decreased significantly during the stimulant condition but did not change during the relaxant condition. This suggests a sympathetic gastric response to the stimulant condition. The observed lack of concomitant changes in HR or RSA indicates that this effect may be organ-specific.
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