Autonomic Burnout: Early Coactivation of the Sympathetic and Parasympathetic Systems Predicts Autonomic Downregulation and the Accumulation of Internalizing Symptoms Over Time

• In Event: A Multisystem Perspective for Understanding the Role of Physiological Regulation in Child Development

Abstract

Internalizing symptom development has been associated with lower parasympathetic activation (respiratory sinus arrhythmia; RSA), proposed to reflect limited regulatory capacity (Hinnant & El-Sheikh, 2009), and with heightened sympathetic activation (skin conductance level; SCL), proposed to reflect chronic hypervigilance (Kagan et al., 1987). However, the majority of previous research has investigated these autonomic branches in isolation (Stone et al., 2020). This fails to acknowledge complex patterns of physiological coordination, as activity in one branch cannot be used to infer activity in the other (Berntson et al., 2008). Drawing from previous findings, internalizing risk may be specific to a pattern of reciprocal sympathetic activation in which reduced RSA and increased SCL reflect a tendency toward maximal arousal. This hypothesis would predict that individuals with heightened SCL who also maintain high levels of RSA (coactivation) may be protected from internalizing symptoms, as parasympathetic activation compensates for sympathetic activation to maintain moderate arousal. However, researchers have also speculated that coactivation of both autonomic systems is physiologically taxing, and may result in greater allostatic wear over time. Thus, the present study seeks to examine how patterns of autonomic activity are associated with symptoms of psychopathology and autonomic function concurrently and over time.

Data were drawn from a study of 339 children (64% male; 70% African American) recruited in kindergarten, oversampling for behavior problems. Psychophysiological measures and teacher-reported psychopathology were collected annually from kindergarten to second grade. RSA and SCL during the initial baseline at the kindergarten assessment were standardized and combined in two composite indices of autonomic activity (Berntson et al., 2008). Cardiac autonomic balance (CAB; RSAz–SCLz) reflects the degree of reciprocal activation, with positive values reflecting parasympathetic dominance/lower arousal, and negative values reflecting sympathetic dominance/higher arousal. Cardiac autonomic regulation (CAR; RSAz+SCLz) captured overall autonomic activity, with positive values reflecting coactivation and negative values reflecting coinhibition. Neither index related to age or gender (p>.8).

Correlation analyses indicated that, contrary to expectations, CAB (high SCL and low RSA) was not associated with internalizing symptoms at any time point. CAR at kindergarten was not correlated with concurrent internalizing (p=.8), but was associated with symptoms at second grade (r=.18, p=.02). Thus, a multilevel growth model was conducted, revealing that coactivation was associated with an increase in symptoms over time (b=.11, p=.05), whereas coinhibition was associated with a decrease (b=-.15, p=.003; Figure 1).

Additional multilevel models were run to examine the effect of coactivation on levels of resting physiological activation over time. Results indicated that coactivation was associated with a decrease over time in both baseline RSA (b=-.13, p=.04) and SCL (b=-2.11, p<.001; Figure 2), whereas coinhibition was associated with an increase in RSA (b=.28, p<.001) and stable SCL (b=.06, p=.83).

Results suggest that children with heightened resting SCL may attempt to regulate arousal through increased RSA, but this pattern of coactivation is not sustainable, resulting in a blunting of both sympathetic and parasympathetic systems over time, and an accumulation of internalizing symptoms.

Authors

• Cassidy M. Fry, Pennsylvania State University, University Park
  Presenting Author

• Lisa M. Gatzke-Kopp, Pennsylvania State University, University Park
  Non-Presenting Author