Introduction For centuries physicians and healers have noted the relationships between psychological well-being and physical health, between various kinds of psychological stress and physical ailments and diseases. Quotes from great physicians, and the enduring medical literature from ancient times to the present, abound with stories and pronouncements about these relationships, some well documented, all reflecting the observations and thinking of their time In modern medicine, the relationship between stress and immune system suppression has been well established by both animal and human research; psychological, physiological and environmental stress can lead to a breakdown in immune resistance, and many of the mechanisms and pathways of action are well understood. In the presence of stress, a large and complex number of mechanical, chemical, and immune changes take place as the body attempts to defend itself or restore homeostasis. Until recently, however, the relationship between stress management and enhancement of immune function was not as easily demonstrated in scientific, neurohumoral terms. Now, however, with the huge leap in technological medicine, in microchemistry and neurobiology and immunology, the pathways of action of immune enhancement are coming into focus. The Rationale of Psychoneuroimmunology The role of the autonomic nervous system, of the limbic/hypothalamic/ pituitary axis, and of the neuropeptides and other neurotransmitters and neuromodulators in mind-body interactions is being intensely studied, and is providing the rationale for self-regulation of the immune system. Many communication links between the central nervous system and the immune system exist; up to the present time, whenever a unique neuropeptide is discovered, receptors are subsequently found for the new neuropeptide on immune system cells. Not only do immune system cells receive messages from the central nervous system via neuropeptides, but aome immune cells actually secrete neuropeptides themselves, sending chemical messages back to the central nervous system. The same chemicals in the brain that control moods, perceptions and actions are also made by the immune system. Thus the basis for a cybernetic feedback loop between the central nervous system and the immune system is clearly established. Not only do psychological states effect the immune system, but also the immune system influences brain, behavior, and mood states. The same rationale Elmer Green proposed for psychophysciologic self-regulation is also emerging as the modus operandi of psychoimmunologic self regulation. According to this rationale, perception (or imagery) elicits mental and emotional responses, generating limbic, hypothalamic, and pituitary responses which bring about physiologic changes which are again then perceived and responded to, completing a cybernetic feedback loop. In fact, clinical psychoneuroimmunology may be seen as a subcategory of psychophysiologic self-regulation. Immune System Correlates of Emotional States Of great interest for the psychoneuroimmunology clinician is the fact that in animal research the greatest modifier of the immune response to stress has been the amount of control the animal is allowed to exert over the stressor. In human research control (or the absence of control) has appeared most often as the dominant factor in the outcome, or process, being measured. The exceptional cancer patient, the hardy personality, the participative patient, a fighting spirit, are some of the characteristics cited in study after study associated with positive outcome and enhanced immune function. Conversely, helplessness and hopelessness, passivity, depression, inability to express emotion, the uncomplaining and compliant patient are characteristics often cited as associated with negative outcomes and lowered immune competence. Some variation of these themes can be found in essentially every cancer study, providing mounting evidence for the influence of emotional (limbic) factors in clinical psychoneuroimmunology. We
are gradually developing an understanding of how volitional mechanisms
determine physiologic response, and of how mentation gets translated
into action. By now the mechanisms of walking, talking, and serving
a tennis ball via the sensory-motor cortex and the striate musculature
are quite thoroughly understood, although the exact relationships
between image, volition, and eventual behavioral response may be
as yet undefined. Supported by the concepts of Claude Bernard, Flanders
Dunbar, W. B. Cannon, and Hans Selye, an understanding of how mind
influences and controls the autonomic nervous system, affects cardiovascular
behavior and gastrointestinal responses, is now widely recognized
and systematically investigated. Only in the last decade, however,
are specific mechanisms being discovered whereby visualization (volitional
mental imagery) can have a direct physiological effect on the immune
system. It is becoming evident that the central nervous system and
the immune system are "hard wired" together, and what some physicians
and others have known intuitively, and empirically, for hundreds
of years is being validated. |
