Cardiac sympathetic activation and parasympathetic withdrawal during psychosocial stress exposure in 6‐month‐old infants

Abstract

Infant autonomic reactivity to stress is a potential predictor of later life health complications, but research has not sufficiently examined sympathetic activity, controlled for effects of physical activity and respiration, or studied associations among autonomic adjustments, cardiac activity, and affect in infants. We studied 278 infants during the repeated Still-Face Paradigm, a standardized stressor, while monitoring cardiac activity (ECG) and respiratory pattern (respiratory inductance plethysmography). Video ratings of physical activity and affect were also performed. Respiratory sinus arrhythmia (RSA) and T-wave amplitude (TWA) served as noninvasive indicators of cardiac parasympathetic and sympathetic activity, respectively. Responses were compared between infants who completed two still-face exposures and those who terminated after one exposure due to visible distress. Findings, controlled for physical activity, showed robust reductions in respiration-adjusted RSA and TWA, with more tonic attenuation of TWA. Infants completing only one still-face trial showed more pronounced autonomic changes and less recovery from stress. They also showed elevated minute ventilation, suggesting hyperventilation. Both reductions in adjusted RSA and TWA contributed equally to heart rate changes and were associated with higher negative and lower positive affect. These associations were more robust in the group of distressed infants unable to complete both still-face trials. Thus, cardiac sympathetic activation and parasympathetic withdrawal are part of the infant stress response, beyond associated physical activity and respiration changes. Their association with cardiac chronotropy and affect increases as infants' distress level increases. This excess reactivity to social stress should be examined as a predictor of future cardiovascular disease.

Exposure to antenatal corticosteroids and infant cortisol regulation

“…The ‘Repeated Still Face Paradigm’ ( Mesman et al, 2009 ; Tronick, 2003 ) was used as the ‘stressor’ at 6 and 12 months of infant age. The ‘Still Face Paradigm’ is a well-established ethical ‘stressor’ shown to reliably elicit a physiologic stress response in infants ( Lester et al, 2018 ; Ritz et al, 2020 ). During this procedure, mother and infant sat facing each other about 18–24 in.…”

Risk for internalizing symptom development in young children: Roles of child parasympathetic reactivity and maternal depression and anxiety exposure in early life

“…Therefore, to adjust for these respiration related variables, we calculated the transfer function of RSA per liter V T and performed a within‐subject regression of this index, after natural log transformation to normalize the distribution (ln[RSA/V T ]), on T TOT . We then added each child's resulting residual value for a given task to the grand mean of the unadjusted lnRSA/VT across participants and tasks to obtain the respiration‐adjusted natural‐log transformed RSA value (lnRSA/VTc, hereafter called “RSA c” ) for each participant for each task (Ritz et al, 2020). Adjustments for both V T and T TOT have been shown to improve the expected prediction of stress‐related changes in PNS tone in adults (Grossman et al, 1991; Ritz, 2009; Ritz & Dahme, 2006; Wilhelm et al, 2004) and in young children (Ritz et al, 2012).…”

RSA instability in mothers of preschoolers and adolescents is related to observations of supportive parenting behaviors

“…To isolate the effect of RSA instability and in line with recommendations from prior work, respiration was controlled (Ritz et al, 2020).…”

“…RSA is considered an indirect index of readiness to cope with one's environment, with higher RSA at rest reflecting a greater readiness to respond to environmental challenge. Conversely, heightened RSA in the context of acute stress or social interaction may indicate ineffective efforts to cope with environmental demands (Grossman & Taylor, 2007; Ritz et al., 2020).…”