Comorbid depression and heart rate variability as predictors of aggressive and hyperactive symptom responsiveness during inpatient treatment of conduct-disordered, ADHD boys

The primary objective of the present study was to assess the utility of (1) comorbid depression and (2) parasympathetic influence on cardiac function as markers for treatment response among aggressive preadolescent males. Inpatient records of 53 patients with conduct disorder and attention deficit hyperactivity disorder (17 with a comorbid depressive disorder) were examined, including an intake electrocardiogram and daily tallies of several indices of aggressive behavior across 3 weeks of stay. The relations of comorbid depression, heart rate variability, and residualized heart rate (primarily of sympathetic origin) to treatment response were assessed through analyses of linear growth functions. Significant vagal tone by diagnostic status interactions were obtained for both frequency and duration indices of aggression, whereby nondepressed patients with high vagal tone deteriorated and depressed patients with high vagal tone improved during hospitalization. No such relation was found for attention deficit hyperactivity disorder symptoms. Patients in the comorbid group also exhibited greater heart rate variability than their nondepressed counterparts. Furthermore, residualized heart rate was predictive of maternal substance use and paternal incarcerations. These findings suggest complex relations among treatment response, comorbid depression, and emotion regulation in male preadolescents with severe behavior disorders. Additionally, the differential prediction afforded by vagal tone and residualized heart rate underscores the importance of assessing both parasympathetic and sympathetic indices of cardiac function as distinct physiological markers. Aggr. Behav. 26:425–441, 2000. © 2000 Wiley-Liss, Inc.