Stress and biological aging: A double-edged sword.

It is well accepted that aging is the basis of most degenerative diseases in the elderly. Biological aging is characterized by a gradual accumulation of cellular and molecular defects. An important cause of defects is intense stress, such as oxidative or glycotoxic stress. Genes affecting cellular and organismal longevity are frequently associated with the regulation of cellular anti-oxidative defense and/or with repair functions. Damage, combined with an age-dependent decline in defense and repair systems, results in disturbed homeostasis, leading to aging and diseases. Whereas intense stress induces premature aging, mild stress can induce adaptive processes, stimulating the expression of genetic repair/defense systems, which positively influences life span.