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
Placebo and nocebo effects are positive or negative treatment effects respectively, unrelated to the treatment mechanism, which are induced by patients’ expectations. Placebo and nocebo effects are... Show morePlacebo and nocebo effects are positive or negative treatment effects respectively, unrelated to the treatment mechanism, which are induced by patients’ expectations. Placebo and nocebo effects are known to play a role in treatment effects for various symptoms and conditions, especially in the field of pain. The aim of the current disseration was to increase understanding of placebo and nocebo effects on itch.The results of the studies presented in this thesis further underline that placebo and nocebo effects play a role in itch perception. We found that itch is highly susceptible to suggestions and placebo and nocebo effects can be induced on itch by verbal suggestion and conditioning. Most notably, our findings show for the first time that particularly the combination of conditioning with verbal suggestion is most promising for inducing both placebo and nocebo effects on itch, which is in accordance with placebo research on pain. Moreover, a new and promising finding is that counterconditioning has shown to reverse nocebo effects on itch. Future research may build upon the findings of this thesis to further enlarge our knowledge on placebo and nocebo effects on itch and how to maximize or minimize them, respectively, also in a clinical setting, to eventually optimize available interventions for patients suffering from chronic itch. Show less
The present thesis deal with the diagnostic boundaries between hypochondriasis and obsessive compulsive disorder and between hypochondriasis and another somatoform disorder called non-cardiac chest... Show moreThe present thesis deal with the diagnostic boundaries between hypochondriasis and obsessive compulsive disorder and between hypochondriasis and another somatoform disorder called non-cardiac chest pain. These studies showed that hypochondriasis and both other disorders are valid disorders based on diagnosis-specific symptoms. Furthermore, in the thesis the first randomized controlled trial comparing the efficacy of cognitive behavioural therapy, and a double-blind SSRI (paroxetine) and pill-placebo is described. The short term effects (4 months) and the long term (5 years) of both treatments were compared to each other and to the placebo. It can be concluded that both are effective treatments for hypochondriasis compared to the placebo in the short term, but the significant differences between both active treatments in ameliorating hypochondriacal symptoms disappears during the follow-up, although CBT is more effective in ameliorating comorbid depressive and psychoneurotic symptoms during the follow-up period than the placebo. Furthermore, CBT results in less use of additional psychological or medical help during the follow-up. Finally, the psychometric properties of the first clinician-administered semi-structured interview, the hypochondriasis Y-BOCS, were described. This interview seemed reliable and valid addition to the assessment arsenal measuring hypochondriacal symptoms. Show less
