Non-linear Heart Rate Variability as a Discriminator of Internalizing Psychopathology and Negative Affect in Children With Internalizing Problems and Healthy Controls

Abstract

Background: Internalizing psychopathology and dysregulated negative affect are characterized by dysregulation in the autonomic nervous system and reduced heart rate variability (HRV) due to increases in sympathetic activity alongside reduced vagal tone. The neurovisceral system is however, a complex nonlinear system, and nonlinear indices related to psychopathology are so far less studied in children. Essential nonlinear properties of a system can be found in two main domains: the informational domain and the invariant domain. sample entropy (SampEn) is a much-used method from the informational domain, while detrended fluctuation analysis (DFA) represents a widely-used method from the invariant domain. To see if nonlinear HRV can provide information beyond linear indices of autonomic activation, this study investigated SampEn and DFA as discriminators of internalizing psychopathology and negative affect alongside measures of vagally-mediated HRV and sympathetic activation.Material and Methods: Thirty-Two children with internalizing difficulties and 25 healthy controls (aged 9–13) were assessed with the Child Behavior Checklist and the Early Adolescent Temperament Questionnaire, Revised, giving an estimate of internalizing psychopathology, negative affect and effortful control, a protective factor against psychopathology. Five minute electrocardiogram and impedance cardiography recordings were collected during a resting baseline, giving estimates of SampEn, DFA short-term scaling exponent α1, root mean square of successive differences (RMSSD), and pre-ejection period (PEP). Between-group differences and correlations were assessed with parametric and non-parametric tests, and the relationships between cardiac variables, psychopathology and negative affect were assessed using generalized linear modeling.Results: SampEn and DFA were not significantly different between the groups. SampEn was weakly negatively related to heart rate (HR) in the controls, while DFA was moderately negatively related to RMSSD in both groups, and moderately positively related to HR in the clinical sample. SampEn was significantly associated with internalizing psychopathology and negative affect. DFA was significantly related to internalizing psychopathology.Conclusions: Higher invariant self-similarity was linked to less psychopathology. Higher informational entropy was related to less psychopathology and less negative affect, and may provide an index of the organizational flexibility of the neurovisceral system.

Sex differences in adolescents’ cardiac reactivity and recovery under acute stress: The importance of nonlinear measures

“…Entropy, therefore, was useful to detect anticipated, exposure‐, and math‐related stress. This is in accordance with growing evidence supporting the importance of measuring HR entropy: SampEn was a significant predictor of internalizing psychopathology and negative affect in a study with children with internalizing problems and healthy controls (Fiskum et al, ). A previous study (Fiskum et al, ) concluded that SampEn was a potential marker of dysregulation in the underlying neurovisceral processes vital for emotion regulation.…”

Lower resting cardiac autonomic balance in young adults with current major depression

“…First, ANS function was measured only at rest and not also in response to a physical and/or psychological stressor, which may provide more nuance to the analyses. Although a large body of research has examined resting levels of cardiac vagal control (e.g., Rottenberg, ), and to a lesser extent sympathetic activity (Fiskum et al, ), this study adds to the extant literature by examining a broader pattern of potential autonomic dysfunction in depression within a bivariate autonomic space. More recent research has examined autonomic flexibility in response to physical and psychological stressors (Bylsma et al, ; Daches et al, ).…”

Autonomic complexity and emotion (dys-)regulation in early childhood across high- and low-risk contexts

“…The limited available studies of children suggest similar differences. In middle childhood, children rated by their parents as displaying heightened levels of temperamental negative affect and/or internalizing problems have been shown to demonstrate lower levels of resting cardiac entropy, relative to their lower internalizing peers (Fiskum et al, 2018). Comparable associations have been noted with adolescents in more ecologically valid settings.…”