Robert Ader and Nicholas Cohen
Department of Psychiatry and Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642


During the past 10-15 years, psychoneuroimmunology–the study of the interactions among behavior, neural and endocrine function, and immune processes–has developed into a bona fide field of interdisciplinary research
(Ader 1981a, 1991a). Previously unknown and unsuspected connections between the brain and the immune system provide a foundation for the now numerous observations both (a) that the manipulation of neural and endocrine functions alters immune responses, and the antigenic stimulation that induces an immune response results in changes in neural and endocrine function and (b) that behavioral processes are capable of influencing immunologic reactivity and, conversely, the immune status of an organism has consequences for behavior. This new research indicates that the nervous and immune systems, the two most complex systems involved in the maintenance of homeostasis, represent an integrated mechanism contributing to the adaptation of the individual and the species. Psychoneuroimmunology emphasizes the functional significance of the relationship between these systems–not in place of, but in addition to the more traditional disciplinary analysis of the mechanisms governing functions within a single system.

The range of phenomena that bears on the relationship between behavior
and immunity is quite broad, and no attempt will be made to provide even a cursory summary of all this literature. We focus here on animal studies of the effects of conditioning and stress in the modulation of immune function. There are several more or less programmatic lines of research in humans that the reader may wish to explore. These deal with the immunologic correlates of emotional states (primarily depression), personality traits as modulators immune function, and the effects of stress on immune function. Few generalizations are possible based on currently available data. Although there is no definitive evidence for the implied chain of events, the hypothesis that immune function may mediate the effects of psychosocial factors on the susceptibility to or progression of some disease processes remains tenable. We confine this review, however, to the experimental literature on the modulation of immunity by stress and conditioning. Other recent reviews (e.g.S. Cohen Williamson 1991; Geiser 1989; Kemeny et al 1992; O’Leary 1990) have dealt with personality and emotional factors and immunity and/or disease. Some of these have included an introductory outline of the immune system; an extensive treatment of immune function can be found in any of several recent texts
(e.g. Stites & Ten” 1991).Psychoneuroimmunology: Conditioning and Stress (