Physiological Effects of Placebo Interventions to Increase or Decrease Blood Pressure

A relevant reduction of blood pressure (BP) in placebo-treated control groups is a phenomenon often observed in pharmacological studies of hypertension. This effect was shown to differ from spontaneous remission tendencies and regression to the mean effect by comparing placebo groups with untreated controls. However, it is not fully understood whether these effects are due to a global reaction of the autonomous nervous system (affecting the overall organ systems of the body) or a specific reaction (affecting the cardiovascular system only). We therefore aim to differentiate specific effects (reduction of blood pressure) from global effects (e.g. changes in electrodermal and gastric activity).

In our study we aim to test the following hypotheses:

1. Placebo administration leads to a significant changes of blood pressure compared with untreated controls.
2. The direction of blood pressure change depends on the type of suggestion (either decrease or increase)
3. This effect is specific for blood pressure; changes in electrodermal and gastric activity do not differ between groups.
4. The placebo response can be enhanced by a prestige intervention (information about the suggested drug action given by doctor or in written form).