Development of cardiac autonomic balance in infancy and early childhood: A possible pathway to mental and physical health outcomes

Cardiac autonomic balance (CAB), defined as the relative influences of the sympathetic (SNS) and parasympathetic (PNS) nervous systems on the heart at rest, is a well-established biomarker of mental and physical health in adulthood (Kemp & Quintana, 2013). SNS and PNS functioning that, jointly, determine CAB, mature and stabilize between gestation and age five (Alkon, Boyce, Davis, & Eskenazi, 2011), co-developing with capacity to regulate distress during challenge and social engagement (Porges & Furman, 2011). This review integrates existing work in developmental, clinical, and medical sciences to propose a theoretical model of CAB development from gestation through early childhood and its putative relations with later functioning. By age five, CAB may reflect biological embedding of regulatory strategies that lay the groundwork for risk or resilience: The same profiles of SNS and PNS functioning associated with limited regulatory support in infancy and exposure to early adversity predict poor mental and physical health problems in adulthood (e.g., Beauchaine, 2001; Oosterman et al., 2010; Suurland, van der Heijden, Smaling, et al., 2017). In three key questions, we identify areas of consensus and remaining gaps in existing work to guide the next generation of research on early CAB development as a possible pathway from early experiences to mental and physical health outcomes.