Children exposed to institutional rearing exhibited reduced SNS activation to social
stressors, blunted vagal withdrawal to a nonsocial
stressor, and blunted cortisol reactivity, indicating a consistent pattern of reduced engagement of stress response systems to
environmental challenges following
early psychosocial deprivation.
In humans, both the HPA system and the autonomic nervous system show developmental changes in infancy, with the HPA axis becoming organized between 2 and 6 months of age and the autonomic nervous system demonstrating relative stability by 6 to 12 months of age.63 The HPA axis in particular has been shown to be highly responsive to child - caregiver interactions, with sensitive caregiving programming the HPA axis to become an effective physiological regulator of stress and insensitive caregiving promoting hyperreactive or hyporeactive HPA systems.17 Several animal models as well as human studies also support the connection between caregiver experiences in
early postnatal life and alterations of autonomic nervous system balance.63 - 65 Furthermore, children who have a history of sensitive caregiving are more likely to demonstrate optimal affective and behavioral strategies for coping with stress.66, 67 Therefore, children with histories of supportive, sensitive caregiving in
early development may be better able to self - regulate their physiological, affective, and behavioral responses to
environmental stressors and, consequently, less likely to manifest disturbed HPA and autonomic reactivity that put them at risk for stress - related illnesses such as asthma.