Old age consists of ages nearing or surpassing the average life span of human beings, and thus the end of the human life cycle. Old people have limited regenerative abilities and are more prone to disease, syndromes, and sickness than other adults. The medical study of the aging process is gerontology, and the study of diseases that afflict the elderly is geriatrics

The boundary between middle age and old age cannot be defined exactly because it does not have the same meaning in all societies. People can be considered old because of certain changes in their activities or social roles. Examples: people may be considered old when they become grandparents, or when they begin to do less or different work - retirement.

Physical Changes

There is often a general physical decline, and people become less active. Old age can cause, amongst other things:

Wrinkles and liver spots on the skin

Change of hair colour to gray or white

Hair loss

Lessened hearing

Diminished eyesight

Slower reaction times and agility

Reduced ability to think clearly

Difficulty recalling memories

Depressed mood

Lessening or cessation of sex, sometimes because of physical symptoms such as erectile dysfunction in men, but often simply a decline in libido

Greater susceptibility to bone diseases such as osteoarthritis