Measurement of brain age: Conceptual issues and neurobiological indices

Alterations in brain function are increasingly thought to play a role in the impaired regulation of endocrine-autonomic systems during the aging process. 1-3 Such age-dependent endocrine imbalances, in turn, have been suggested gradually to induce widespread physiological decline in peripheral organ systems. Support for this view of the brain as a “pacemaker” of aging derives from findings which show that age-related changes occur in neuroendocrine regulatory mechanisms 1,2 as well as in peripheral endocrine functions. 1,4,5 Thus, current evidence indicates that the study of altered brain mechanisms should prove of major importance in attempts to understand the causes and implications of hormonal changes during mammalian aging.