Human Studies

Influential theoretical accounts take the position that classical conditioning can induce placebo effects through conscious expectancies. In the current study two different conditioning procedures (hidden and open) were used to separate expectancy from conditioning in order to reveal the role of expectancy in the formation of nocebo hyperalgesia. Eighty-seven healthy females were randomly assigned to three groups (hidden conditioning, open conditioning, and control). Participants were selected according to the Fear of Pain Questionnaire scores and assigned to two subgroups: high and low level of fear of pain (trait). They received electrocutaneous pain stimuli preceded by either an orange or blue color. During the conditioning phase, one color was paired with pain stimuli of moderate intensity (control stimuli) and the other color was paired with pain stimuli of high intensity (nocebo stimuli) in both hidden and open conditioning groups. Only participants in the open conditioning group were informed about this association, however just before the testing phase the expectancy of hyperalgesia induced in this way was withdrawn. In the control group, both colors were followed by control pain stimuli. During the testing phase all participants received a series of stimuli of the same intensity, regardless of the preceding color. Participants rated pain intensity, expectancy of pain intensity and fear (state). We found that nocebo hyperalgesia was induced by hidden rather than open conditioning. The hidden conditioning procedure did not produce conscious expectancies related to pain. Nocebo hyperalgesia was induced in participants with low and high fear of pain and there was no difference in the magnitude of the nocebo effect between both groups. Nocebo hyperalgesia was not predicted by the fear of upcoming painful stimuli.

Recent research has highlighted a need for the psychometric evaluation of instruments targeting core domains of the pain experience in chronic pain populations. In this study, the measurement properties of SF-36, EQ-5D, and HADS were analyzed within the item response-theory framework based on data from 35,908 patients. To assess the structural validity of these instruments, the empirical representations of several conceptually substantiated latent structures were compared in a cross-validation procedure. The most structurally sound representations were selected from each questionnaire and their internal consistency reliability computed as a summary of their precision. Lastly, questionnaire scores were correlated to each other to evaluate their convergent and discriminant validity. Our results supported that SF-36 is an acceptable measure of two independent constructs of physical and mental health. In contrast, although the approach to summarize the HRQoL construct of EQ-5D as a unidimensional score was valid, its low reliability rendered practical model implementation of doubtful utility. Finally, rather than being separated into two subscales of anxiety and depression, HADS was a valid and reliable measure of overall emotional distress. In support of convergent and discriminant validity, correlations between questionnaires showed that theoretically similar traits were highly associated whereas unrelated traits were not. Our models can be applied to score SF-36 and HADS in chronic pain patients, but we recommend against using the EQ-5D model due to its low reliability. These results are useful for researchers and clinicians involved in chronic pain populations, as questionnaires' properties determine their discriminating ability in patient status assessment.

To investigate mental and physical health comorbidity with chronic back or neck pain in the Chinese population, and assess the level of disability associated with chronic back or neck pain.

Pain catastrophizing is linked to a range of negative health and treatment outcomes, although debate continues about how best to define and treat it, since most interventions produce only modest benefit. This study aimed to contribute to theory-driven development of these treatments by exploring the role of perseverative thinking in pain catastrophizing, along with the higher order beliefs, called metacognitions, that might shape it.

Psychological interventions designed to enhance positive affect are promising ways to promote adaptive functioning in people with chronic pain. However, few studies have addressed the efficacy of positive affect interventions in chronic pain populations and examined which patients can benefit more from them. The aim of the present study was to identify mediators and moderators of the best possible self intervention (BPS) in fibromyalgia patients.

Abdominal pain is common and is associated with high disease burden and health care costs in pediatric acute recurrent and chronic pancreatitis (ARP/CP). Despite the strong central component of pain in ARP/CP and the efficacy of psychological therapies for other centralized pain syndromes, no studies have evaluated psychological pain interventions in children with ARP/CP. The current trial seeks to 1) evaluate the efficacy of a psychological pain intervention for pediatric ARP/CP, and 2) examine baseline patient-specific genetic, clinical, and psychosocial characteristics that may predict or moderate treatment response.