Copyright @ 2007 American Academy of Child and Adolescent Psychiatry. Unauthorized reproduction of this article is prohibited. Externalizing and Internalizing Problems in Relation to Autonomic Function: A Population-Based Study

Objective: To investigate whether externalizing and internalizing problems are related to lower and higher heart rate (HR), respectively, and to explore the relationship of these problems with respiratory sinus arrhythmia (RSA) and baroreflex sensitivity (BRS). Moreover, to study whether problems present at both preschool and preadolescent age show stronger associations with autonomic function than those that were not. Method: In a population cohort of 10- to 13-year-old children (N = 931; 11.6 T 0.5 years; 47 % boys), autonomic measurements in supine and standing position were performed at school. RSA and BRS were determined by spectral analysis. Current externalizing and internalizing problems were assessed by the Child Behavior Checklist and problems at age 4 to 5 retrospectively by the Preschool Behavior Questionnaire.Results: At supine rest, current externalizing problems were associated with lower HR and higher RSA, but not with BRS and current internalizing problems with higher HR and lower RSA, but not with BRS. These results were specifically found in children with problems that were retrospectively reported to have been also present at preschool age. Standing-induced changes in autonomic parameters were unrelated to the behavioral dimensions. Conclusions: Externalizing and internalizing problems are associated with divergent autonomic patterns, suggesting autonomic underarousal and overarousal, respectively. Problems starting early in life may specifically account for this. This should be confirmed in prospective studies. J. Am. Acad. Child Adolesc. Psychiatry, 2007;46(3):378Y386. Key Words: autonomic nervous system, baroreflex sensitivity, psychopathology, respiratory sinus arrhythmia. An extensive literature suggests an association between both externalizing and internalizing psychopathology and autonomic nervous system function in adults as well as in children (Beauchaine, 2001; Lorber, 2004