This PhD research dealt with neurobiological and behavioral aspects of pain. Previous research has demonstrated that pain sensitivity can be worsened as a result of learned negative expectations, a... Show moreThis PhD research dealt with neurobiological and behavioral aspects of pain. Previous research has demonstrated that pain sensitivity can be worsened as a result of learned negative expectations, a phenomenon termed nocebo hyperalgesia –a counterpart to placebo analgesia. This PhD dissertation describes neuroimaging and biobehavioral experimental studies as well as a review and a meta-analysis concerned with such learned effects on pain. The research adds to a growing literature that has been challenging antiquated understandings of pain as a bottom-up process. We conducted a series of biobehavioral studies to further our understanding of how bottom-up pain signaling can be influenced by top-down processing. We examined the types of experiences, such as receiving negative information or experiencing a negative effect first-hand, that may lead to stronger nocebo effects. Behavioral paradigms were used to model real-life pain experiences, through validated methods, novel learning manipulations, as well as a close examination of emotional correlates such as fear. Concurrently, innovative neuroscientific methods –including pharmacological manipulations– were used to examine the biobehavioral underpinnings of learned nocebo responses. Our findings add to the growing knowledgebase from the field of nocebo hyperalgesia, demonstrating that learning by experience can decisively influence the processing and perception of noxious stimuli. Show less
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
This thesis deals with emotional and social influences on childhood somatic complaints. Strong support is provided for the idea that negative affect contributes to the development of somatic... Show moreThis thesis deals with emotional and social influences on childhood somatic complaints. Strong support is provided for the idea that negative affect contributes to the development of somatic complaints in childhood. In addition, the studies described give information about the type and levels of negative affect associated with somatic complaints in childhood. When appraisal is characterized by the experience of little control over negative situations and emotions, this is likely to directly cause more feelings of negative affect and also to contribute to a more negative processing of emotions: children who feel little control evidently use more maladaptive emotion regulation strategies. This negative emotional processing further contributes to negative affect and subsequent somatic complaints. These relationships between negative affect and somatic complaints are even present at subclinical levels of emotional problems. With regard to social problems, it is found that they have an effect on somatic complaints that is fully mediated by aspects of children’s emotional functioning: self-perceived social problems indicate lower feelings of control and more maladaptive emotion regulation. Show less
