Sickness behavior as a new target for drug development.

Sickness behavior refers to the nonspecific symptoms (anorexia, depressed activity, loss of interest in usual activities, disappearance of body-care activities) that accompany the response to infection. Increasing evidence suggests that these symptoms are part of an organized defense response to antigenic challenge and that they are mediated by the neural effects of cytokines such as interleukin 1. An understanding of the mechanisms involved in these effects should permit development of new drugs aimed at decreasing sickness or promoting recovery processes.