Pain
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Comparative Study
Sympathetic skin response following painful electrical stimulation is increased in major depression.
Patients with major depressive disorder have repeatedly been described to exhibit increased thresholds upon experimentally applied pain stimuli to the skin as compared to respective controls. Since the sensory-discriminative component of stimulus perception, e.g. for warmth, cold and vibration, appears to be unaltered in depression, higher central nervous centres have been assumed to cause this phenomenon. To date, hardly any attention has been paid to the efferent components of the noxious reflex loop. ⋯ Intriguingly, the noxious stimuli were still perceived less painful in the patient group. Pain perception weakly correlated with disease severity. From these data, we conclude that despite the diminished pain perception, the autonomic reflex loop following noxious stimulation is not affected in patients with major depressive disorder, and that the increase in sympathetic outflow is not directly related to the perceived pain as in controls, but might rather be attributed to the autonomic dysfunction known for the disease.
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Elevated resting blood pressure (BP) is hypoalgesic in healthy individuals, but this effect is absent in adults with chronic somatic pain. This study tested whether BP-related hypoalgesia is similarly altered in individuals with a history of chronic visceral pain in childhood. Resting BP was assessed in 94 adolescents and young adults with a known history of childhood functional abdominal pain (FAP) and 55 comparable healthy controls. ⋯ Subgroup analyses indicated that BP-related hypoalgesia (in healthy controls) and FAP-linked absence of this hypoalgesia was observed only among females. Result suggest that childhood visceral chronic pain may be associated with relatively long-lasting dysfunction in overlapping systems modulating pain and BP that persists even after FAP resolves. Potential implications for later hypertension risk are discussed.
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It is widely assumed that distraction reduces pain. Similarly, it is assumed that pain distracts from concurrent, unrelated cognitive processing, reducing performance on difficult tasks. Taken together, these assumptions suggest pain processing and cognitive function engage an overlapping set of domain-general, capacity-limited mental resources. ⋯ Path analyses showed that variations in pain completely mediated this effect, and that even within a given heat level, trial-by-trial fluctuations in pain predicted decrements in performance. In sum, these findings argue that overlapping cognitive resources play a role in both pain processing and executive working memory. Future studies could use this paradigm to understand more precisely which components of executive function or other cognitive resources contribute to the experience of pain.
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More than 1 in 10 adults in the general population experience chronic widespread body pain (CWP), which lies at one end of a continuous spectrum of pain ranging in both severity and duration. Neuroendocrine factors can modify the effect of known psychological and psychosocial risk factors for progression along the spectrum of pain and development of CWP, and genetic variants that affect neuroendocrine and neural processing potentially affect susceptibility to chronic pain development. We have examined variants across genes encoding the beta2-adrenergic receptor (ADRB2) and catecholamine-O-methyltransferase (COMT) - key neuroendocrine signalling factors - in a large population-based sample to determine whether these may be involved in pain progression and CWP development. ⋯ There were no associations of either CWP or pain status with COMT genotypes or haplotypes. These results are the first to suggest that functional ADRB2 variants are involved in regulating pain status at a population level. A role for COMT in chronic pain development was not identified, though could not be excluded.
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The Quantitative Sensory Testing (QST) protocol of the German research network on neuropathic pain (DFNS) encompassing all somatosensory modalities assesses the functioning of different nerve fibers and of central pathways. The aim of our study was: (1) to explore, whether this QST protocol is feasible for children, (2) to detect distribution properties of QST data and the impact of body site, age and gender and (3) to establish reference values for QST in children and adolescents. The QST protocol of the DFNS with modification of instructions and pain rating was used in 176 children aged 6.12-16.12years for six body sites. ⋯ Girls were more sensitive to thermal detection and pain stimuli, but not to mechanical detection and pain stimuli. Reference values differ from adults, but distribution properties (range, variance, and side differences) were similar and plausible for statistical factors. Our results demonstrate that the full QST protocol is feasible and valid for children over 5years of age with their own reference values.