How to define the old age?

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There is no generalized acceptance to define old age. The World Health Organization acknowledges that 65 years old is the commonly accepted definition in most advanced nations, but it suggests a limit somewhere between 50 and 55 years old for developing nations (WHO, 2012). In any case, the limits of grouping the elderly according to chronological age are obvious. A crucial aspect to consider here is the component of social construction in the way individuals and nations define who is elderly; the shared meaning of the concept is created through interactions among people in society and may therefore vary in different cultures. This is exemplified by the cliché that you are only as old as you feel. Still, it is obvious that both from the physical and the psychological point of view, the life experience of a 65-year-old is very different from that of a 90-year-old. In relation to this, it is now common to divide the elderly population into three subgroups: the young-old (approximately 65–74 years), the middle-old (ages 75–84 years), and the old-old (over age 85 years).

WHO (2012) Definition of an older or elderly person. In: Health statistics and information systems. World Health Organization. http://www.who.int/healthinfo/survey/ageingdefnolder/en/