Adrenal function in aging:

Age-related changes of the adrenal secretory pattern: possible role in pathological brain aging

The biosynthetic dissociation of the adrenocortical secretion occurring with age may have a pathogenetic role in the pathophysiology of brain aging. We studied cortisol and DHEAS secretion in healthy old and young subjects, in senile dementia, in major depression of elderly subjects and in healthy centenarians. A clear age-related decline of DHEAS secretion was well evident in healthy centenarians, and a further decrease in DHEAS concentration was found in old depressed patients and moreover in the demented ones, by comparison with age-matched controls. The circadian profile of serum cortisol was clearly flattened in old subjects, due to the selective increase in the cortisol nocturnal levels, particularly evident in demented subjects; on the other hand, the morning serum cortisol levels were not significantly different among centenarians, young and old controls. The molar ratio between cortisol and DHEAS showed a significant age-related increase; the occurrence of senile dementia and of major depression played an additive role, by comparison to physiological aging. The qualitative and quantitative modifications of the adrenocortical secretion occurring with aging seem mainly dependent on age itself, but the occurrence of pathological conditions may amplify these changes. Since cortisol and DHEAS play opposite effects on the central nervous system, the evaluation of the ratio between cortisol and DHEAS seems to be a good marker of the neuroendocrine features in old subjects.

The process of aging changes the interplay of the immune, endocrine and nervous systems

The immune, endocrine and nervous systems interact with each other by means of cytokines, hormones and neurotransmitters. Interaction is dependent on specific receptors and respective signaling pathways in target cells. During aging, changes occur on many levels of these global systems which depend on oxidative damage, non-enzymatic glycosylation, mitochondrial mutations, defects in cell cycle control, mitotic dysregulation, genome instability, telomere shortening and other chromosomal pathologies. An alteration of the numerical value of a parameter of one system can lead to changes of the numerical value of a variable of another system. In a non-linear dynamic process these changes can contribute to the aging phenotype. Although it is extremely difficult to dissect linear interrelations of three global systems during aging, this review attempts to identify some simple linear pathways. Furthermore, it is demonstrated that chronic inflammatory diseases may accelerate the aging process. This review also reveals that new statistical and computational methods are necessary to unravel the complexity of the aging process.