Pain
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The tendency to select threatening over benign interpretations of ambiguous bodily sensations and cues characterises young people with chronic pain. However, previous studies disagree over whether these biases extend to nonbodily harm situations such as social evaluation. Understanding the content of these biases is crucial to the development of pain management strategies seeking to modify such biases. ⋯ Although negative interpretations of bodily harm and social evaluation situations emerged as distinct factors, benign interpretations across situations were best captured by a common factor and 2 situation-specific factors (ie, bifactor model). Group comparisons showed that young people with moderate-to-high pain interference were more likely to endorse negative interpretations across all situations, and less likely to manifest a general benign interpretational style, than youth without interfering pain, although some of these group differences were explained by co-occurring anxiety and depressive symptoms. Replication of these findings is needed.
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Two recent studies suggest that experimental pain sensitivity is associated with low-grade systemic inflammation. However, only 2 biomarkers have been identified, and the studies were conducted in adult individuals where confounding effects of comorbid diseases cannot be excluded. We therefore tested associations between pain sensitivity and 119 inflammation-related serum biomarkers in 827 healthy adolescents (15-19 years) in the population-based Tromsø Study: Fit Futures. ⋯ Results for heat and pressure pain tolerance were remarkably similar, strengthening the generalizability of our findings. In this cohort of young healthy individuals, we found a relationship between inflammation-related biomarkers and pain tolerance and thresholds. Biomarkers with anti-inflammatory and analgesic effects predominated, suggesting that the development of prophylactic dietary or pharmaceutical treatments may be possible.
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Native Americans (NAs) have a higher prevalence of chronic pain than other U. S. racial/ethnic groups, but there have been few attempts to understand the mechanisms of this pain disparity. This study used a comprehensive battery of laboratory tasks to assess peripheral fiber function (cool/warm detection thresholds), pain sensitivity (eg, thresholds/tolerances), central sensitization (eg, temporal summation), and pain inhibition (conditioned pain modulation) in healthy, pain-free adults (N = 155 NAs, N = 150 non-Hispanic Whites [NHWs]). ⋯ There were no group differences on any measure, except that NAs had lower cold-pressor pain thresholds and tolerances, indicating greater pain sensitivity than NHWs. These findings suggest that there are no group differences between healthy NAs and NHWs on peripheral fiber function, central sensitization, or central pain inhibition, but NAs may have greater sensitivity to cold pain. Future studies are needed to examine potential within-group factors that might contribute to NA pain risk.
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Localizing pain is crucial because it allows for detecting which part of the body is being hurt and identifying in its surrounding which stimulus is producing the damage. Nociceptive inputs should therefore be mapped according to somatotopic ("which limb is stimulated?") and spatiotopic representations ("where is the stimulated limb?"). Because the body posture constantly changes, the brain has to realign the different spatial representations, for instance when the arms are crossed with the left hand in the right space and vice versa, to adequately guide actions towards the threatening object. ⋯ Relative to the uncrossed posture, sighted participants' performances were decreased when the hands were crossed, whatever the instruction be. Early blind participants' performances were affected by crossing the hands during spatial instruction, but not during anatomical instruction. These results indicate that nociceptive stimuli are automatically coded according to both somatotopic and spatiotopic representations, but the integration of the different spatial reference frames depends on early visual experience and ongoing cognitive goals, illustrating the plasticity and the flexibility of the nociceptive system.
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Observational Study
Sub-optimal learning of tactile-spatial predictions in patients with complex regional pain syndrome.
In complex regional pain syndrome (CRPS), tactile sensory deficits have motivated the therapeutic use of sensory discrimination training. However, the hierarchical organisation of the brain is such that low-level sensory processing can be dynamically influenced by higher-level knowledge, eg, knowledge learnt from statistical regularities in the environment. It is unknown whether the learning of such statistical regularities is impaired in CRPS. ⋯ This caused greater precision on prediction errors, resulting in predictions that were driven more by momentary spatial changes and less by the history of spatial changes. These results suggest inefficiencies in higher-order statistical learning in CRPS. This may have implications for therapies based on sensory retraining whose effects may be more short-lived if success depends on higher-order learning.