background The autonomic nervous system is one of the main stress axes in the body. It has been suggested that alterations in its function are involved in the etiology of psychopathology.
aim To investigate whether externalizing and internalizing problems are related to autonomic function, as measured by heart rate (hr), respiratory sinus arrhythmia (rsa) and baroreflex sensitivity (brs). In addition, to study whether problems already present at pre-school age show stronger associations with autonomic function than problems not present at that age.
method In a population cohort of 10- to 13-year-old children (N=931; 11.6+/-0.5 yrs; 47% boys), autonomic measurements were performed at school. rsa and brs were determined by spectral analysis. Current externalizing and internalizing problems were assessed by means of the Child Behavior Checklist and problems at age 4-5 retrospectively by the Preschool Behavior Questionnaire.
results Current externalizing problems were associated with lower hr and higher rsa, but not with brs; current internalizing problems with higher hr and lower rsa, but not with brs. These results were particularly evident in children with problems that were already present at preschool age.
conclusion Externalizing and internalizing problems are associated with divergent autonomic patterns, suggesting autonomic underarousal and overarousal, respectively. Problems that start early in life may specifically account for this.