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 in Preadolescents ANDREA DIETRICH, M.A., HARRIE ¨ TTE RIESE, PH.D., FROUKE E.P.L. SONDEIJKER, M.A., KIRSTIN GREAVES-LORD, M.A., ARIE M. VAN ROON, PH.D., JOHAN ORMEL, PH.D., JAN NEELEMAN, M.D., AND JUDITH G.M. ROSMALEN, PH.D. ABSTRACT 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; Ortiz and Raine, 2004). One of the best-replicated biological correlates of child psychopathology is a lower resting heart rate (HR) in children with externalizing problems (Lorber, 2004; Ortiz and Raine, 2004). This Accepted October 12, 2006. Ms. Dietrich and Drs. Riese, Ormel, Neeleman, and Rosmalen are with the De- partment of Psychiatry and Graduate School of Behavioral and Cognitive Neurosciences, and Dr. van Roon is with the Department of Internal Medicine, University Medical Center Groningen, University of Groningen; Ms. Sondeijker and Ms. Greaves-Lord are with the Department of Child and Adolescent Psychi- atry, Erasmus Medical Center Rotterdam; Drs. Ormel, Neeleman, and Rosmalen are with the Graduate School for Experimental Psychopathology, University of Groningen; and Dr. Neeleman is with the Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, The Netherlands. This research is part of the Study of Allostatic Load as a Unifying Theme (SALUT), in cooperation with the Tracking Adolescents_ Individual Lives Survey (TRAILS). SALUT is a collaboration between various departments of the University Medical Center Groningen and the University Medical Center Utrecht, the Netherlands. SALUT is financially supported by The Netherlands Organization for Scientific Research (Pionier 900-00-002) and by the participating centers. Participating centers of TRAILS include various departments of the University of Groningen, the Erasmus University Medical Center of Rotterdam, the Radboud University of Nijmegen, the University of Leiden, and the Trimbos Institute, The Netherlands. TRAILS is financially supported by grants from The Netherlands Organization for Scientific Research (GB-MW 940-38-011, GB-MAGW 480- 01-006, GB-MAGW 457-03-018, GB-MAGW 175.010.2003.005, ZonMw 100-001-001 BGeestkracht[ Program, and ZonMw 60-60600-98-018), the Sophia Foundation for Medical Research (projects 301 and 393), the Ministry of Justice, and by the participating centers. The authors thank all of the children, their parents, and their teachers who willingly participated. Correspondence to Andrea Dietrich, Department of Psychiatry, Hanzeplein 1, 9713 GZ Groningen, The Netherlands; e-mail: A.Dietrich@med.umcg.nl. 0890-8567/07/4603-0378Ó2007 by the American Academy of Child and Adolescent Psychiatry. DOI: 10.1097/chi.0b013e31802b91ea 378 J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 46:3, MARCH 2007