2009

Background: Respiratory sinus arrhythmia (RSA) has been proposed as a physiological marker of emotion-regulation capacity, and shown to be cross-sectionally associated with
depression. Little is known about the role of RSA as a predictor of (subclinical) depressive symptoms over time and as a modifier of the depressogenic effect of stressful life events (SLEs).
Methods: In a longitudinal population-based study with data collected in 1653 adolescents twice (at age 11 and 13.5, respectively), RSA was assessed in supine position at the first assessment wave. Depressive symptoms were assessed at both waves and SLEs experienced between the two waves at the last wave. Results: Low levels of RSA were not associated with oncurrent or future depressive symptoms, and did not enhance the depressogenetic effects of SLEs. Conclusions: In a normal population of young adolescents, a low level of RSA does not identify adolescents at risk for depressive symptoms when confronted with SLEs. In post-hoc analyses, among those reporting high exposure to stressful life events, higher RSA tended to predict less self-reported anxiety and more self-reported somatic symptoms as compared to those with lower RSA.

Objective: Depression is a well-known risk factor for cardiovascular disease and mortality. Dysregulation of the autonomic nervous system (ANS) and the hypothalamic-pituitary-adrenal (HPA-) axis have been proposed as underlying mechanisms. Several studies suggest that only a subset of the depression symptoms account for associations with cardiovascular prognosis. This study examined the possibility that somatic and cognitive-affective depressive symptoms are differentially related with the ANS and the HPA-axis in a large non-clinical sample of preadolescents. Methods: Self-reported somatic and cognitive-affective depressive symptoms were examined in relation to heart rate variability (HRV), spontaneous baroreflex sensitivity (BRS), and the cortisol awakening response (CAR) in 2049 preadolescents (mean age 11.1 years, 50.7 % girls) from the general population cohort TRAILS. Results: Physiological measurements were not associated with the overall measure of depressive symptoms. Somatic depressive symptoms were negatively related to HRV and BRS, and positively to the CAR; cognitive-affective depressive symptoms were positively related to HRV and BRS, and negatively to the CAR. Associations with the CAR pertained to boys only. Conclusions: Somatic and cognitive-affective depressive symptoms differ in their association with both cardiac autonomic and HPA-axis function in preadolescents. Particularly somatic depression symptoms may mark cardiac risk.