Objective: This study describes the developmental changes and individual stability in autonomic nervous system (ANS) resting and challenge responses for a cohort of primarily Latino, low-income children during the first 5 years of life.
Methods: ANS measures of the parasympathetic nervous system (respiratory sinus arrhythmia [RSA]) and sympathetic nervous system (preejection period [PEP]) were collected on a representative sample of the full cohort at 6, 12, 42, and 60 months of age (N = 378). The children participated in a standardized protocol to elicit ANS responses during resting and challenging states. Reactivity profiles were created to summarize each child's combined RSA and PEP reactivity (i.e., change in response to challenges compared to a resting state).
Results: Results showed developmental changes in ANS measures from 6 to 60 months: heart rate decreased, RSA increased, PEP increased, and frequency of classic reactivity profiles of reciprocal sympathetic activation and parasympathetic withdrawal increased. Correlations showed moderate stability for resting and challenging conditions but not reactivity.
Conclusions: These findings suggest that low-income Latino children, from 6 to 60 months of age, showed ANS developmental changes and moderate individual stability for resting and challenge responses but not for reactivity. There was a significant shift in the frequency of children with the classic reactivity profile from 6 by 60 months of age. This is the first cohort study to show the developmental changes in ANS and young children's increase in their biologic sensitivity to the environment during the first 5 years of life.
From the *Department of Family Health Care Nursing, School of Nursing, University of California, San Francisco, California; †College for Interdisciplinary Studies and Faculty of Medicine, University of British Columbia, Vancouver, Canada; ‡Center for Environmental Research and Children's Health, School of Public Health, University of California, Berkeley, California.
Received May 2011; accepted August 2011.
The contents of this publication are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS and NIH.
This study was funded by the National Institute of Environmental Health Sciences, (NIEHS) 2 P01 ES009605 and National Institute of Child Health and Development (NICHD) ARRA 445211-33252-01 HD058091.
Disclosure: The authors declare no conflict of interest.
Address for reprints: Abbey Alkon, RN, PhD, Department of Family Health Care Nursing, School of Nursing, University of California, San Francisco, 2 Koret Way Box 0606, San Francisco, CA 94143; e-mail: firstname.lastname@example.org.