Experimental social fear: immunological, hormonal, and autonomic concomitants

The aims of the two studies were to investigate the relationship between emotions and immune responses in an experimental setting by inducing social fear and to broaden our understanding of bodily reactions by examining both cardiovascular and hormonal responses. Seventy-nine healthy subjects were confronted with a situation in which relatively strong social fear was induced in the laboratory. Social fear was induced by having to prepare and give an oral presentation in front of an audience. Thirty additional healthy subjects formed a control group; they followed exactly the same procedure, but, instead of the "public speaking situation," they were subjected to a nondemanding task of the same duration. The results indicate that public speaking evoked fear as shown by both elevated feelings of tenseness and negative bodily sensations. Moreover, the data clearly show enhanced cardiovascular activity, elevated plasma hormone levels, and changes in immunological parameters (natural killer cell number and T helper/inducer cells). The control group reported significantly less feelings of tenseness and negative bodily sensations and showed a decrease in cortisol, prolactin, and beta-endorphin levels. Although some variation on immune responses was present, no variation on cardiovascular activity occurred in the control group during the experiment. The results show that there is indeed a relationship between emotion and immune responses. In addition, the data collected on body responses point to a direct mediating effect of sympathetic-adrenal medulla activity and an indirect mediating effect of hypothalamo-pituitary-adrenal axis activity.