Epidemiologic aspects

Abstract

A common definition (World Health Organization 2011) describes elderly individuals as persons aged 65 and over. A previous definition given by the WHO even defined persons only 60 or more years old as elderly, but this cutoff is not generally accepted. In this context, it is necessary to discuss the definition of age. The definition of an calendarian cutoff for defined age groups merely depends on social consensus and not primarily on physiological changes that may occur even years before. Age-associated physiological changes in the endocrine system or in lens elasticity may start much earlier even in healthy subjects: between age 40 and age 45 for the endocrine system and during puberty for lens elasticity. A reliable and valid threshold value for significant changes in physiology cannot be calculated and applied due to a great variety of interindividual aging patterns and courses.