The influence of proximal risk on the early development of the autonomic nervous system

In this paper we review the evidence linking the early development of the autonomic nervous system in early childhood to four proximal risk factors: maternal stress during pregnancy, maternal substance use during pregnancy, poor-quality parent-child interactions, and specific disruptions in parenting behavior. A clear pattern of altered autonomic function emerges in children exposed to proximal risk, marked by reduced parasympathetic tone under conditions of both homeostasis and challenge, accompanied by increased sympathetic tone in some cases. This pattern of autonomic activity would support increased vigilance and active defense responses, which, in an environment of high proximal risk, may be adaptive in the short-term. However, in the long-term maintaining such a state may impose a high allostatic load. The current paper reviews and interprets the current literature and discusses future directions. (c) 2013 Elsevier Inc. All rights reserved.