Effects of stress on pain threshold and tolerance in children with recurrent abdominal pain.

Models of stress-induced hyperalgesia state that exposure to stress can exaggerate subsequent pain experiences. Studies using both animal and human subjects have shown evidence for hyperalgesia as a function of stress [e.g., Jorum E. Analgesia or hyperalgesia following stress correlates with emotional behavior in rats. Pain 1988;32:341-48; Peckerman A, Hurwitz BE, Saab PG, Llabre MM, McCabe PM, Schneiderman N. Stimulus dimensions of the cold pressor test and the associated patterns of cardiovascular response. Psychophysiology 1994;31:282-90; Gameiro et al. Nociception and anxiety-like behavior in rats submitted to different periods of restraint stress. Physiol. Behav. 2006;87:643-49; Lucas et al. Visceral pain and public speaking stress: neuroendocrine and immune cell responses in healthy subjects. Brain Behav. Immun. 2006;20:49-56]. However, the role of stress in pediatric pain is not well understood. This study examined stress reactivity and pain tolerance and sensitivity in a population of children with Recurrent abdominal pain (RAP). Forty-nine children meeting criteria for RAP (28 female; mean age 13years; range 9-17years) were randomly assigned to either a condition in which they completed an experimental stressor paradigm (stress interview, serial subtraction task) followed by a pain task (cold pressor) or a condition in which they received the pain task prior to the stress tasks. Children who underwent the stress tasks before the pain task exhibited lower levels of pain tolerance than those who received the pain task first (p<.01); no differences were found between the two groups in pain threshold or pain intensity ratings. Further, pain tolerance was not related to individual differences in physiological reactivity (heart rate change) to the stressor. The present research demonstrates the first evidence of the occurrence of stress-induced hyperalgesia in a pediatric pain population.

Attentional biases to pain and social threat in children with recurrent abdominal pain.

OBJECTIVES: To test whether children with recurrent abdominal pain (RAP) exhibit subliminal (nonconscious) and supraliminal (conscious) attentional biases to pain-related words, and to determine correlates of these biases. Previous research indicates that individuals attend to disorder-relevant threat words, and in this study, attentional biases to disorder-relevant threat (pain), alternative threat (social threat), and neutral words were compared. METHODS: Participants were 59 children with RAP who completed a computer-based attentional bias task. Participants and their parents also completed questionnaires measuring pain, somatic complaints, anxiety/depression, and body vigilance. RESULTS: Children with RAP showed attentional biases toward subliminal pain-related words and attentional biases away from supraliminal pain-related words. Participants' attentional biases to social threat-related words were marginally significant and also reflected subliminal attention and supraliminal avoidance. Attentional biases were related to parent and child reports of pain, body vigilance, and anxiety/depression. CONCLUSIONS: Children with RAP show nonconscious attention to and conscious avoidance of threat-related words. Their attentional biases relate to individual differences in symptom severity. Implications for models of pediatric pain and future studies are discussed.

Parent reports of coping and stress responses in children with recurrent abdominal pain.

OBJECTIVE: To examine relationships among coping, stress responses, pain, somatic symptoms, and anxious/depressed symptoms in a sample of children and adolescents with recurrent abdominal pain (RAP). METHOD: We assessed parents' reports of coping and involuntary responses to stress in relation to pain, somatic symptoms, and symptoms of anxiety and depression in a sample of 174 children and adolescents with RAP. RESULTS: Based on parent reports, children's primary control engagement coping (e.g., problem solving, emotional modulation) and secondary control engagement coping (e.g., acceptance, distraction, positive thinking) in response to pain were associated with fewer somatic complaints and symptoms of anxiety and depression; secondary control engagement coping was also associated with less pain. Involuntary engagement (e.g., physiological reactivity, rumination) and disengagement (e.g., escape, inaction) responses to pain were associated with more somatic symptoms and higher levels of anxiety and depression. CONCLUSIONS: We highlight implications of these findings for understanding processes of coping and stress reactivity in children with RAP.