This dissertation covered several relevant cycles of placebo research with the main aim to optimize placebo effects in medical contexts. Firstly, a literature review described how the immune system... Show moreThis dissertation covered several relevant cycles of placebo research with the main aim to optimize placebo effects in medical contexts. Firstly, a literature review described how the immune system can be impacted by placebo effects and their underlying learning theories. In the following chapter, these learning theories were integrated to form an optimal research design by means of pharmacological conditioning to fit a specific patient group: children with juvenile idiopathic arthritis. Secondly, this dissertation focused on developing placebo information strategies to harness placebo beliefs and educate persons about the relevancy of placebo effects in practice. These insights are valuable because treatment expectations can have a positive or negative effect on treatment outcomes. Finally, insights from placebo learning theories and placebo information strategies were combined in an integrative experimental research design. This research design employed a more ethical form of placebo use because participants were made aware of placebos, called open-label placebos. In this last study we demonstrated that open-label placebo analgesia can be induced by combining learning theories and placebo information strategies. Altogether, this dissertation provided insights in learning mechanisms, communication strategies, and research paradigms that involve the optimization of placebo effects in medical context. Show less
Placebo effects are health improvements, for example pain reduction, due to an inert treatment. These effects are typically ascribed to a person’s expectations about the beneficial outcomes of... Show morePlacebo effects are health improvements, for example pain reduction, due to an inert treatment. These effects are typically ascribed to a person’s expectations about the beneficial outcomes of the placebo. The literature and experimental research in the current dissertation shows that expectancies, and thereby placebo effects, can be induced via verbal suggestion, conditioning, and mental imagery. Especially verbal suggestions may enhance analgesic treatments for patients. We found, for the first time, that mental imagery of reduced pain can induce analgesia via its effects on pain expectancies. We also observed that people’s expectations about the effectiveness of medications depend on the route of administration and targeted symptom. These findings suggest that harnessing placebo effects by targeting expectancies is promising for enhancing standard clinical care of physical symptoms. Show less