Cardiac Vagal Control in Depression and Attention Deficit/Hyperactivity Disorder

The importance of the vagus nerve in the two way communication between the brain and the heart has been known for over 100 years. Recently, integrative theories that link central nervous system structures to cardiac vagal regulation, such as the polyvagal theory, have of late emerged. Based on the polyvagal theory, the respiratory sinus arrhythmia (as an index of cardiac vagal control) is considered as a psychophysiological marker of many aspects of behavioural functioning and emotion regulation in both children and adults. Although a lack of sensitive heart rate autonomic control likely reflects impaired cardiac nervous system regulation, the sophisticated brain-heart interactions are incompletely understood. Importantly, cardiac vagal dysregulation is associated with the increased risk of cardiovascular morbidity reflecting various pathophysiological states. Thus, we believe that the identifying of cardiac vagal control changes in mental disorders should represent an initial step towards the understanding of a potential pathomechanisms leading to later cardiac adverse outcomes; especially in children and adolescents.