title: Conditioned pain modulation in children and adolescents: effects of sex and age.
abstract: Conditioned pain modulation (CPM) refers to the diminution of perceived pain intensity for a test stimulus following application of a conditioning stimulus to a remote area of the body, and is thought to reflect the descending inhibition of nociceptive signals. Studying CPM in children may inform interventions to enhance central pain inhibition within a developmental framework. We assessed CPM in 133 healthy children (mean age = 13 years; 52.6% girls) and tested the effects of sex and age. Participants were exposed to 4 trials of a pressure test stimulus before, during, and after the application of a cold water conditioning stimulus. CPM was documented by a reduction in pressure pain ratings during cold water administration. Older children (12-17 years) exhibited greater CPM than younger children (8-11 years). No sex differences in CPM were found. Lower heart rate variability at baseline and after pain induction was associated with less CPM, controlling for child age. The findings of greater CPM in the older age cohort suggest a developmental improvement in central pain inhibitory mechanisms. The results highlight the need to examine developmental and contributory factors in central pain inhibitory mechanisms in children to guide effective, age appropriate pain interventions.
  
  
  CONCLUSIONS
  In this healthy sample, younger children exhibited less CPM than did older adolescents, suggesting a developmental improvement in CPM. Cardiac vagal tone was associated with CPM across age. The current findings may inform the development of targeted, developmentally appropriate pain interventions for children.
authors.affiliation: Pediatric Pain Program, Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, California 90095-1752, USA. jtsao@mednet.ucla.edu
authors.forename: Jennie C I
authors.initials: JC
authors.lastname: Tsao
authors.forename: Laura C
authors.initials: LC
authors.lastname: Seidman
authors.forename: Subhadra
authors.initials: S
authors.lastname: Evans
authors.forename: Kirsten C
authors.initials: KC
authors.lastname: Lung
authors.forename: Lonnie K
authors.initials: LK
authors.lastname: Zeltzer
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Naliboff
mesh_terms: D000293:Adolescent; D000375:Aging; D058443:Catastrophization / Q000209:etiology / Q000523:psychology; D002648:Child; D003213:Conditioning, Psychological / Q000502:physiology*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D010146:Pain / Q000150:complications* / Q000209:etiology / Q000523:psychology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D010812:Physical Stimulation / Q000009:adverse effects; D012727:Sex Characteristics
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