Mechanisms of Psychogenic Fever

Abstract

Psychogenic fever is a psychosomatic disease especially seen in young adults. However, the mechanisms explaining how psychological stress increases core body temperature (Tc) in these patients are not yet fully understood. Therefore, this article reviews the current understanding of the mechanisms of stress-induced hyperthermia and the distinctive effects of acute, repeated, or chronic stress on Tc in laboratory animals. Acute exposure to anxiety-provoking stress induces a transient, monophasic increase in Tc. In contrast, repeated stress either induces anticipatory hyperthermia, reduces diurnal changes in Tc, or slightly increases Tc throughout the day. Chronically stressed animals also show depressive-like behaviors and display an enhanced hyperthermic response to a novel stress. A fearful experience in the past induces conditioned hyperthermia to the fear context. The high Tc that psychogenic fever patients develop may be a complex of many kinds of hyperthermic responses previously modeled in animals. Animal studies also show that psychological stress increases Tc via mechanisms distinct from infectious fever, which requires proinflammatory mediators. However, psychological stress and immune insults may increase Tc via a common efferent pathway, i.e., the rostral medullary raphe region-sympathetic nervous system circuit.