Sex Moderates the Relationship Between Nausea Severity and Heart Rate Variability in Adolescents and Young Adults.

BACKGROUND: Nausea is a common complaint among children and is particularly prevalent in children with functional abdominal pain (FAP), with nearly half of children with FAP also endorsing nausea. Dysfunction of the autonomic nervous system, which can be indexed by heart rate variability (HRV), leads to abnormalities in gastric electrical activity that are associated with GI symptoms. AIMS: To evaluate that relationship between nausea severity and HRV in adolescents and young adults with a history of FAP and to assess for sex differences. METHODS: Participants were pediatric patients with a diagnosis of FAP who were recruited from a pediatric GI clinic between 1993 and 2007 for a prospective study of the course of FAP. Study analyses focused on the cross-sectional relationship between HRV, indexed by standard deviation of the R-R interval (SDRRI) and high-frequency (HF) power, and nausea severity collected during a follow-up visit in late adolescence and young adulthood. RESULTS: Controlling for age and BMI, a significant nausea by sex interaction emerged for both SDRRI and HF power. Tests of conditional effects of nausea by sex showed that the inverse relation between nausea severity and both SDRRI and HF was significant for females but not for males. CONCLUSIONS: This is the first study to evaluate the relationship between nausea severity and HRV. Greater nausea severity was associated with lower HRV in females but not in males. Further validation of these results may provide insight into novel treatment approaches for females with nausea that target vagal tone.

"My Body Hates Me": A Qualitative Analysis of the Experience of Functional Nausea in Adolescent Girls and Their Mothers.

Nausea is a somatic sensation typically associated with the need to vomit in order to remove a toxin from the body. When nausea occurs in the absence of a specific structural cause or toxin, it is classified as a functional gastrointestinal disorder (FGID). Functional nausea was newly recognized in 2016 as a FGID in children and little is known about its prevalence, course or patient experiences. Nausea co-occurring with functional abdominal pain in childhood has been associated with long-term risk for anxiety and ongoing somatic symptoms into young adulthood. However, few studies have focused uniquely on the experience and impact of nausea on youth. The present study aimed to qualitatively understand the experiences of adolescent girls with functional nausea and their parents. Five mother-daughter dyads were recruited from a specialized pediatric gastroenterology clinic focused on nausea and completed semi-structured interviews. Interviews were transcribed and coded using interpretive phenomenological analysis (IPA). Four main themes emerged: nausea interference, body frustration, misunderstanding of symptoms, and maternal helplessness and guilt. These themes were similar to prior studies on the experiences of youth with chronic pain but also indicated unique challenges due to nausea, such as significant food restriction and subsequent weight loss.