2010

Objective. Why is low resting heart rate (HR) associated with antisocial behavior (ASB: aggression and rule-breaking) in adolescence? Theory suggests that personality traits mediate this relationship but differently with age. In the present study this age-effect hypothesis is tested; we expected that the relationship between HR and aggression would be mediated in preadolescence by the personality trait behavioral inhibition, but not by sensation seeking. However, the relationship between HR and rule-breaking in adolescence was predicted to be mediated by sensation seeking, but not by behavioral inhibition. Hypotheses were tested separately for boys and girls. Method. HR in supine position was assessed in TRAILS respondents (N = 1752; 48.5% boys) at age 11. Rule-breaking and aggression at age 16 were assessed with two subscales from the Youth Self Report (YSR) questionnaire. Personality (i.e., sensation seeking and behavioral inhibition) was measured at age 11, 13.5, and 16 with the Early Adolescent Temperament Questionnaire-Revised (EATQ-R), Behavioral Inhibition System/ Behavioral Activation System (BIS/BAS) scales, or NEO Personality-Index Revised (NEO-PI-R). Results. In boys, lower HR was associated with aggression and rule-breaking in adolescence. The association between HR and rule-breaking was mediated by sensation seeking in adolescence, but not in preadolescence. Girls’ HR was not associated with ASB and no mediating effects were found. Conclusions. Our findings support the age-effect hypothesis in boys’ rule-breaking behavior. This shows that the association between HR and ASB depends on age, gender, and subtype of ASB.

Despite their extensive use, the reproducibility of cardiac autonomic measurements in children is not well-known. We investigated the reproducibility of short-term continuous measurements of heart rate (HR), heart rate variability (HRV, time and frequency domain), and spontaneous baroreflex sensitivity (BRS, frequency domain) in the supine and standing position in 57 children (11.2+/-0.7 yrs, 52.6% boys). Reproducibility between two sessions within a two-week interval was evaluated by intraclass correlation coefficients (ICCs), standard error of measurement, coefficients of variation (CVs), limits of agreement, and Bland–Altman plots. HR and HRV were moderately-to-highly (ICC=.63–.79; CV= 5.7%–9.7%) and BRS moderately (ICC=.49–.63; CV=11.4%–14.0%) reproducible. While the BRS measurements were slightly less reproducible than the HR and HRV measurements, all can be reliably applied in research, thus implicating sufficient capacity to detect real differences between children. Still, clinical studies focusing on individual changes in cardiac autonomic functioning need to address the considerable random variations that may occur between test-retest measurements.

Effortful control is thought to foster adaptive action in defensive contexts, and may thereby protect individuals against anxious inhibition and focus on their own distress. We examined if effortful control predicted adolescents’ perceived arousal, unpleasantness, and control as well as autonomic (HR) and HPA-axis (cortisol) responses during social stress. The data came from a focus sample of TRAILS (TRacking Adolescents’ Individual Lives Survey), a prospective population study of Dutch adolescents (N = 715; mean age 16.11, SD = 0.59; 50.9% girls), who participated in a laboratory session including a social stress task (public speaking and mental arithmetic). Perceived and physiological stress measures were assessed before, during, and after the social stress task. Effortful control was measured using various questionnaires and informants, as well as by means of a reaction time (RT) task assessing response inhibition. Overall, adolescents with high questionnaire-based effortful control tended to feel more relaxed, pleasant, and in control during the laboratory session than adolescents with lower levels of control, and had stronger HR responses to the stress test. Adolescent girls with high inhibitory control as measured by the RT task also had strong HR responses, but inhibitory control was associated with high rather than low perceived arousal. Our results suggest that both questionnaire and RT measures of effortful control predict strong HR responses to challenging situations, but associational patterns diverge with regard to perceived stress measures.