Psychoneuroimmunology and aging.

<bold>Background: </bold>The senescence of the immune system is a complex phenomenon, characterized by impairment of several lymphocyte activities and generally considered a state of immune dysregulation. Aging is a condition associated with many social changes likely to induce psychological stress, which is often perceived as uncontrollable and can lead, in some cases, to clinically relevant depression. In the recent years a growing interest has been raised for the study of bidirectional interactions between the central nervous system and the immunological network (psychoneuroimmunology).<bold>Objective and Methods: </bold>We analyzed the possibility that chronic psychological distress and depression could worsen some immune functions in the aged. We postulate the neuroendocrine mechanisms of psychoimmune interaction, analyzing both the human and animal studies focused on aging.<bold>Results: </bold>The data from the literature reviewed suggest a significant impact of affective disorders on immune functions in the elderly subjects. This psychoimmune imbalance appears particularly important when the studies are carried out in otherwise healthy aged people.<bold>Conclusions: </bold>Here we reviewed the relationships between psychological stress and depression and immunological functions, with particular regard to those aspects pertinent to the aging process. The clinical relevance of these interactions remains to be elucidated, but the high frequency in the aged of autoimmune, infectious, and neoplastic diseases suggests to focus on the psychoneuroimmune interactions in the old age. We also propose some outlines for future studies concerning psychoneuroimmunology and aging. [ABSTRACT FROM AUTHOR]