Possible mechanisms of psychogenic fever in human subjects

Among those who develop episodic or persistent high core body temperature (Tc) without any inflammatory causes, there are patients whose high Tc is associated with psychological stress. Some patients develop a high fever (up to 40 °C) when they are exposed to emotional events, whereas others show a persistent low-grade fever (37–38 °C) during situations of chronic stress. Their high Tc has been called “psychogenic fever”. Psychogenic fever is a stress-related, psychosomatic disease especially seen in young adults. The mechanisms underlying how psychological stress causes acute or persistent increases in Tc in these patients are still poorly understood. However, studies have demonstrated that psychogenic fever is not attenuated by antipyretic drugs but by psychotropic drugs that have anxiolytic and sedative properties, relaxation training or psychotherapy. In this symposium, I would like to give a historical overview of psychogenic fever first. Then, I would like to discuss the possible mechanisms of psychogenic fever based on the findings obtained by stress interviews. Some patients develop high Tc during a stress interview, e.g. 1.0 °C increase within one hour. Increase in Tc is not associated with blood levels of prostaglandin E₂ or pyrogenic cytokines such as IL-1β or IL-6, but with increase in blood catecholamine. Furthermore, psychogenic fever patients show heightened heart rate response to orthostatic stress compared with healthy subjects. These findings suggest that psychogenic fever in humans is induced by different mechanisms from infection/inflammation-associated fever, where proinflammatory mediators play a pivotal role. Rather, heightened sympathetic activity may be involved in this phenomenon.