Overreactivity of the psyche or the soma? Interindividual associations between psychosomatic symptoms, anxiety, heart rate, and end-tidal partial carbon dioxide pressure.

Current research has all but refuted previous suggestions about the role of hyperventilation as a proximal, common cause of psychosomatic symptoms. As an alternative, it has been proposed that the experience of psychosomatic symptoms is primarily associated with psychological mechanisms, i.e., with enhanced tendencies of distressed individuals to focus their attention on bodily sensations and to evaluate these in a catastrophic manner. Although this hypothesis has received considerable empirical support, physiological influences on symptom reporting have not, as yet, been fully explored. In this study, contributions of psychological and physiological factors were studied among a group of 83 normal healthy male subjects by an assessment of the interindividual relationships between symptom experience in daily life, situational and dispositional anxiety, baseline end-tidal partial carbon dioxide pressure (PCO2), and heart rate. Trait anxiety and end-tidal PCO2 each contributed separately to the prediction of the psychosomatic symptom score. Trait anxiety explained nearly one third of the symptom variance, and an additional 4% was explained by PCO2. Psychological symptoms were more strongly associated with anxiety and somatic symptoms, more strongly with PCO2. Heart rate only tended to be correlated with symptom reporting. Analysis of covariance among subgroups of extreme-symptom reporters supported the correlational findings by demonstrating that the association between hyperventilation and symptom reporting remained intact when psychological influences were factored out. The findings suggest that reports of psychosomatic symptoms represent two distinct components: one that is primarily psychological (and is unrelated to physiological factors) and a second that reflects objective variance in physiological functioning. The influence of the first component is probably greater than that of the second.