THE PSYCHOPHYSIOLOGY OF ANXIETY

Abstract

The recent and remote literature on the psychophysiology of anxiety was reviewed and re-evaluated on the basis of recent advances in clinical and experimental psychiatry, physiology and learning theory. Operational hypotheses have been set forth relating the experimental data to the clinical phenomena, with special attention to the role of epinephrine. The first section reviewed the evidence that anxiety responses produce a relatively higher proportion of epinephrine than norepinephrine from the adrenal medulla. The next section cited literature concerning the response of "normal" and "neurotic" subjects to the injection of epinephrine. Apparently conflicting data are accounted for by 2 variables: first, the strength of the subject''s previously learned association between acute anxiety and sympathomimetic symptoms, and second, the degree of current anxiety reinforcement in the experimental setting. It was suggested that the sympathomimetic symptoms produced by epinephrine during anxiety further reinforce the individual''s anxiety, evoking a self-generating, spiraling anxiety reaction. A third section presented some very recent experiments which demonstrate sedative-like and parasympathetic effects following the systemic administration of epinephrine. It is postulated that epinephrine may function as a hormonal feedback mediator to the trophotropic function of the hypothalamus (Hess), producing the sedative-like and parasympathetic symptoms found in intense or prolonged anxiety. Thus the initial adrenal medullary secretion during anxiety may evoke sympathomimetic symptoms or cues which further reinforce the anxiety response, while more prolonged secretion may evoke parasympathetic and fatigue or sedative-like effects which compensate for the initial stages of the anxiety. Since epinephrine is a more prominent secretion in anxiety than in other responses, such as anger, and since it is more potent in producing sympathomimetic and subsequent sedative-like effects, epinephrine may account for many of the clinical phenomena characteristic of anxiety.