Abstract
There is increasing evidence that verbal suggestions accompanying placebo interventions
can alter autonomic functions. The underlying mechanisms of these changes are not
well understood. However, previous studies point at the specificity of such effects.
The aim of the experiment was to lower blood pressure by a placebo intervention and
to investigate the specificity of autonomic changes. Forty-five healthy participants
received a single administration of an active drug (a homeopathic remedy), an identically-looking
placebo drug, or no drug. Active drugs and placebo drugs were administered in a double-blind
design and were accompanied by verbal suggestions of a blood-pressure lowering effect.
Systolic and diastolic blood pressure, the electrocardiogram, electrodermal activity,
and the electrogastrogram were recorded during 30 min before and after the intervention, and changes in situational anxiety were assessed.
Results indicated a decrease of systolic blood pressure in the placebo group, as compared
to the control group. Diastolic blood pressure levels, heart rate, respiratory sinus
arrhythmia, skin conductance, gastric slow-wave frequency and situational anxiety
did not change differentially between groups. In conclusion, the reduction in systolic
blood pressure following the placebo intervention could not be attributed to stress
relief or anxiety reduction. Rather, results suggest that the placebo intervention
specifically reduced systolic blood pressure.
Keywords
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Article info
Publication history
Published online: July 15, 2011
Accepted:
June 20,
2011
Received in revised form:
May 24,
2011
Received:
December 29,
2010
Identification
Copyright
© 2011 Elsevier B.V. Published by Elsevier Inc. All rights reserved.
