structural:scholar_edition, stylistic:tone
Markers

See also: DNA damage theory of aging

Three unique markers of frailty have been proposed: (a) loss of any notion of invincibility, (b) loss of ability to do things essential to one's care, and (c) loss of possibility for a subsequent life stage.

Old age survivors on average deteriorate from agility in their early retirement years (65-79) to a period of frailty preceding death. This deterioration is gradual for some and precipitous for others. Frailty is marked by an array of chronic physical and mental problems which means that frailty is not treatable as a specific disease. These problems, coupled with increased dependency in the basic activities of daily living (ADLs) required for personal care, add emotional problems: depression and anxiety. In sum, frailty has been depicted as a group of "complex issues", distinct but "causally interconnected", that often include "comorbid diseases", progressive weakness, stress, exhaustion, and depression.

Healthy humans after age 50, accumulate endogenous DNA single- and double-strand breaks in a linear fashion in cellular DNA. Other forms of DNA damage also increase with age. After age 50 a decline in DNA repair capability also occurs. These findings are in accord with the theory that DNA damage is a fundamental aspect of aging in older people.