Autonomic nervous system development and its impact on neuropsychiatric outcome

Abstract

The central autonomic nervous system (ANS) is essential for maintaining cardiovascular and respiratory homeostasis in the newborn and has a critical role in supporting higher cortical functions. At birth, the central ANS is maturing and is vulnerable to adverse environmental and physiologic influences. Critical connections are formed early in development between the ANS and limbic system to integrate psychological and body responses. The Polyvagal Theory, developed by Stephen Porges, describes how modulation of the autonomic vagal impulse controls social responses and that a broad range of neuropsychiatric disorders may be due to impaired vagal balance, with either deficient vagal tone or excessive vagal reactivity. Under additional circumstances of prematurity, growth restriction, and environmental stress in the fetus and newborn, the immature ANS may undergo "dysmaturation". Maternal stress and health as well as the intrauterine environment are also quite important and have been implicated in causing ANS changes in the infant and neuropsychiatric diseases in children. This review will cover the aspects of ANS development and maturation that have been associated with neuropsychiatric disorders in children.

Figure 1.. Factors Influencing Autonomic Nervous System (ANS) Development

Multiple factors influence autonomic nervous system development during the preconceptional and fetal periods, as well as during infancy and childhood. Acting through developmental plasticity of the limbic system these factors may influence the development of neuropsychiatric disorders in childhood.

Figure 2.. Anatomy of the Central Autonomic Nervous System (ANS) and Limbic System Connections

Together, the limbic and brain stem ANS centers regulate emotional, learned, and physiological body responses to the environment. The limbic system includes the amygdala, thalamus, fornix, hippocampus, hypothalamus, and cingulate gyrus. Parasympathetic tone and vagal activity is generated from the dorsal motor nucleus of the vagus (DMV) and from the nucleus ambiguus (NA). The nucleus of the solitary tract (NTS) is an important brainstem ANS center with both sympathetic and parasympathetic system functions. It receives peripheral afferent input from peripheral chemoreceptors and pulmonary mechanoreceptors to control cardiovascular and respiratory system functions. A behavioral response or stress triggers the limbic system to affect ANS tone which results in physiologic effects on heart rate, respiratory rate, and blood pressure.