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Oxytocin has been shown to increase trust, decrease anxiety and affect learning as has been observed in conditioning paradigms. Trust, anxiety and learning are important factors that influence placebo effects. In this study we investigated whether oxytocin can increase placebo analgesia, decrease nocebo hyperalgesia, and influence extinction processes of both. Eighty male volunteers were assigned to a 40 IU of oxytocin nasal spray group, or to a placebo control group. Placebo analgesia and nocebo hyperalgesia were induced by a conditioning procedure in combination with verbal suggestions. The results demonstrate that the conditioning procedure successfully elicited significant placebo analgesia and nocebo hyperalgesia responses (p < .001). Furthermore, extinction was observed (p < .001), although placebo and nocebo responses did not return to baseline and remained significant. Oxytocin did not influence placebo analgesia or nocebo hyperalgesia and had no effect on extinction. This study provides support against the placebo-boosting effects of oxytocin and was the first one to demonstrate that it also did not influence nocebo effects or extinction processes, however, these results pertain to only a male sample. As managing placebo and nocebo effects has widespread clinical implications, further research should investigate other neurobiological or behavioral pathways to boost placebo and decrease nocebo effects. Trial registration: The study protocol was preregistered on the website www.trialregister.nl under the number NTR6506. Perspective: The present study demonstrated that placebo analgesia and nocebo hyperalgesia can be successfully induced by conditioning and verbal suggestions. We could not confirm the hypothesis that oxytocin affects either of these phenomena. Other pharmacological agents and behavioral manipulations for increasing placebo and decreasing nocebo effects should be investigated.
Learn More >The brainstem has been discussed as the main player in the pathogenesis of migraine. Dysfunctional brainstem nuclei and their abnormal connections to other key brain centers may contribute to headache and other symptoms of migraine. In the present study, 32 patients with migraine without aura (MWoA) and 32 age- and sex-matched healthy controls (HCs) underwent resting-state fMRI scans. We used masked independent analysis (mICA) to investigate whether patients with MWoA exhibited abnormal brainstem nuclei-cortical functional connectivity (FC). The mICA can suppress adjacent physiological noise and prevent results from being driven by the much stronger signals of the surrounding structures. Regional homogeneity (ReHo) was used to investigate whether the brainstem regions with abnormal FC to other brain areas exhibited abnormal regional neuronal activity. Patients with MWoA showed significantly weaker FC between the posterior pons and the left superior parietal lobule, the left middle temporal gyrus and the left middle frontal gyrus. Furthermore, patients with MWoA exhibited significantly decreased ReHo values in the posterior pons compared with HCs, and the posterior pons ReHo value was significantly negatively correlated with HIT-6 scores in the MWoA group. Patients with MWoA exhibited functional abnormalities in the posterior pons and weakened connections between the posterior pons and several key cortical brain areas involved in pain processing during the resting state. Perspective: This study provided increased evidence that the pons is involved in pathophysiological mechanism of migraine, and weakened connections suggest that the touch and pain sensation of migraine sufferers may not be properly relayed to cortical processing areas, which may be associated with the pathogenesis of MWoA.
Learn More >Chronic pain affects 1-3 million Canadian children and adolescents and their families. The primary objective of the Partnering For Pain project was to collaboratively identify the top 10 research priorities in pediatric chronic pain.
Learn More >To compare the prevalence of facial pain and headache across various regions in Sweden.
Learn More >Self-reported side effects of pain medication are important determinants of treatment course that can affect patient adherence, medication discontinuation and physician decisions. Yet, few studies have investigated patient-level predictors of self-reported pain medication side effects. The present study sought to fill this gap by exploring the impact of physical or sexual abuse history on self-reported pain medication side effects and considered a mediation model in which those effects are transmitted through a centralized pain phenotype and pain catastrophizing.
Learn More >The hypothalamus plays a key role in both migraine and cluster headache (CH). As brain region-to-region structural correlations are believed to reflect structural and functional brain connectivity patterns, we assessed the structural covariance patterns between the volume of the hypothalamic region and vertex-by-vertex measurements of cortical thickness in patients with migraine and in those with CH relative to healthy controls (HC).
Learn More >Increasing numbers survive cancers in childhood and adolescence. Long-term survivors of cancers in adulthood have increased prevalence of pain and consumption of analgesics. It is not established whether long-term survivors of cancers in childhood and adolescence also have an increased use of analgesics. However, based on increased use of antidepressants and anxiolytics in long-term survivors of cancers in childhood and adolescence, we hypothesized that this group also had increased use of analgesics. Based on data from the two nationwide registers the Cancer Registry of Norway and the Norwegian Prescription Database a cohort of 5585 (52% males) long-term survivors of cancers in childhood, adolescence and early adult life was established. Age and gender adjusted comparisons were made to the general population. The age adjusted one-year periodic prevalence of receiving prescriptions of opioids, benzodiazepines and benzodiazepine-related hypnotics in the study population was increased by 20-50% and the one-year periodic prevalence of receiving prescriptions of gabapentinoids was approximately increased two-fold compared to the general population. For paracetamol and NSAIDs no difference was found. For those survivors, who were persistent or high-dose users of opioids, co-medication with high doses of benzodiazepines and/or benzodiazepine-related hypnotics was far more common than among persistent and high-dose opioid users in the general population. The high prevalence of gabapentinoids may indicate increased prevalence of neuropathic pain in this group. The high degree of co-medication with benzodiazepines and/or benzodiazepine-related hypnotics in survivors on persistent and high-dose opioids might be an indication of problematic opioid use or addiction.
Learn More >Chronic postoperative pain is common and can have a negative impact on quality of life. Recent studies show that genetic risk factors are likely to play a role, although only gene-targeted analysis has been used to date. This is the first genome-wide association study to identify single-nucleotide polymorphisms associated with the development of chronic postoperative pain based on two independent cohorts. In a discovery cohort, 330 women scheduled for hysterectomy were genotyped. A case-control association analysis compared patients without chronic postoperative pain and the 34 who had severe chronic postoperative pain 3 months after surgery. No single-nucleotide polymorphisms reached genome-wide significance, but several showed suggestive associations with chronic postoperative pain (p < 1 × 10 ). Single-nucleotide polymorphisms with significance p < 1 × 10 were followed up in a replication cohort consisting of 203 men and women scheduled for orthopaedic or abdominal surgery. Ten of these patients developed severe chronic postoperative pain. A single-nucleotide polymorphism in NAV3 was significantly replicated with chronic postoperative pain in the replication cohort (p = 0.009). Meta-analysis revealed that two loci (IQGAP1 and CRTC3) were significantly associated with chronic postoperative pain at 3 months (IQGAP1 p = 3.93 × 10 β = 2.3863, CRTC3 p = 2.26 × 10 , β = 2.4209). The present genome-wide association study provides initial evidence for genetic risk factors of chronic postoperative pain and supports follow-up studies.
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