Autonomic nervous system status and responsiveness and the levels of anxiety in a normal population.

173 We live in times of deadlines and information overload. Many individuals are mentally and emotionally overextended with conscious-or subconscious-feelings of apprehension and worry chronically present. The increased heart rate associated with certain psychological states and disorders has, until recently, primarily been ascribed to increases in the activity of the sympathetic nervous system. However, it is now accepted that decreases in parasympathetic control, that is, decreases in the autonomic 'brake' on heart rate, are much more important than previously assumed. 1,2 Perhaps of greater concern with regard to anxiety disorders are indications of an autonomic inflexibility or decreased responsiveness in the face of a challenge. 1,2 In view of the importance of the autonomic nervous system (ANS) to instantaneously regulate many functions in line with mental and physical needs, lower responsiveness could have a significant influence on physical and psychological well-being. The question is whether anxiety, within the normative range, has an impact on resting ANS functioning and on the ANS responses to moderate everyday challenges. This is a report on the association between resting ANS status and responsiveness, and the levels of anxiety in a group of healthy volunteers. Eight adult volunteers, without previous complaints of anxiety or burnout and not on antidepressants or any medication that influences cardiovascular functioning, took part in the pilot study. Clearance was obtained from the Ethics Committee, Faculty of Health Sciences, University of Pretoria and all volunteers signed informed consent. ANS function was assessed by heart rate variability (HRV) techniques. 3,4 Tachogram recording sessions consisted of a stabilization period of 10 minutes, a 5 min baseline recording, a 5 min recording during a cognitive challenge and a 5 min recording over a recovery period after the cognitive challenge. Focussed attention, elicited and monitored by means of Infinity biofeedback equipment, was employed as the cognitive challenge. It involved an activity screen with a bowling ball animation, with the movement of the ball determined by the extent to which the subject increased the relative power of his/her sensorimotor rhythm. Anxiety was assessed by the State-Trait Anxiety Inventory for Adults. 5 Mean state and trait anxiety for the group fell within the normal range with mean state anxiety at the 48th and mean trait anxiety at the 79th percentile of normal. Negative correlations were seen between parasympathetic control of the heart and levels of state anxiety in the baseline recordings (HF ms 2 : r =-0.714, …