Stress reactivity in childhood functional abdominal pain or irritable bowel syndrome.

Background: Frequent abdominal pain (AP) in childhood has been shown to be associated with elevated experience of stress and with deficits in stress coping, but psychophysiological stress reactivity has been studied rarely. Methods: We examined whether children with frequent AP show altered reactions of the parasympathetic nervous system and the hypothalamic-pituitary-adrenal (HPA) axis during and following an afternoon laboratory social stress task in comparison to healthy children and children with anxiety disorders. Twenty-four children with frequent AP (18 with functional AP and six with irritable bowel syndrome; M = 9.9 years), and 24 healthy controls underwent stressful free speech and arithmetic tasks. Twelve children with anxiety disorders served as second comparison sample. Groups were compared regarding parasympathetic reaction and saliva cortisol concentration. Results: We found no differences in parasympathetic withdrawal between the groups. Concerning the HPA axis, we detected an attenuated cortisol reactivity in children with AP compared to both other groups. Conclusions: This study provides preliminary evidence that childhood AP is not associated with altered parasympathetic withdrawal during stress. It seems to be related to a down-regulated reactivity of the HPA axis. This pattern was ascertained in comparison to healthy children and also in comparison to children with anxiety disorders. Significance: Childhood abdominal pain could be related to down-regulated HPA axis reactivity to stress but not to altered parasympathetic reaction. Children with abdominal pain and children with anxiety disorders exhibit a divergent stress-related HPA axis reaction.