Frailty of older age: the role of the endocrine--immune interaction.

The so-called demographic transition has changed the age structure of the population worldwide, with profound effects on societal organization. The growing number and percentage of old and very old people has compelled the scientific community to focus on age related diseases and peculiar consequences of aging itself such as disability and frailty. Understanding the pathophysiology of frailty, a syndrome characterized by a reduced functional reserve and impaired adaptive capacity that results from cumulative declines of multiple subsystems, and causes increased vulnerability to adverse outcomes, is a major topic in aging research. Aging processes induce multiple changes in the hormones network (menopause, andropause, somatopause and adrenopause), in the immune system, and can modulate their efficiency and effectiveness in determining a response to stressors. These triggering events can unmask frailty in older people. Starting from these assumptions, we analyzed the relationship of the endocrine and immune networks in aging and in the different domains that are characteristically associated with the frailty syndrome, such as disability and sarcopenia, as well as in diseases related to aging such as Alzheimer's dementia and Congestive Heart Failure.